Paper Pulp and Plaster in the Silicone Molds

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After a whole lot of messing around, I finally found something that works well in the silicone rubber molds I made several weeks ago. But we probably can’t call it paper mache. Oh well – I’ve never been much of a purist, anyway.

In the last two weeks I tried just about every combination of ingredients that I could think of. I told you in my last post, about the molds, that I thought I had a formula that would work well, but it turns out I was wrong. The goo captured details really well, but it took forever to dry. And then when I though it was finally dry enough to remove it from the mold, I would inevitably ruin the nose or the eyebrow – whichever part was lowest and collected all the moisture.

Last night I was about to give up, and then I remembered a series of experiments that Jonty, over at Darkside Creations, has been doing with paper pulp and plaster. He shared his results with the Yahoo Papier Mache Art group. (If you haven’t signed up for the group yet, you definitely should). He said that plaster and paper are fairly strong – if I’d been paying more attention, I could have been painting wolves and other critters several weeks ago.

So, as it turns out, the easiest and least expensive “formula” is the one I’ve decided to use for my series of decorative masks. As of this morning, I finally have some pieces that I can finish. The garbage can if full of rejects.

There are several reasons why I decided on this method, but I know it is somewhat fiddly. It will work for my project, but it might not be the best method for whatever project you have in mind.

My criteria were very specific – I wanted pieces that were fairly lightweight but strong, and that could be said to consist primarily of recycled or natural materials. I also wanted the pieces to come out of the molds fairly quickly so they could dry from all sides. And, although I don’t have a big show lined up or anything like that, I wanted a method that could be geared up for production, if I ever did decide to show them. Not that the world will be clammering for decorative hippo masks anytime soon, but that’s just the way my brain works.

When I reread Steve’s suggestion about layers, I realized that I could use paper strips and paste to add strength to the back of the pieces, so the front, the part that actually captures the detail in the mold, can be very thin and not terribly strong. What I’m ending up with is a sandwich consisting of a paper/plaster front, a layer of cheese cloth to add strength to the “skin” so it can be safely handled, and then several layers of brown paper and paste on the back to give the pieces their needed strength.

I don’t have the backs done on any of the pieces yet, but there’s no reason that I can think of why it won’t work just fine. Paper strips and paste are extremely strong when they’re dry, and the paper/plaster skin should be a nice surface to paint. So – here’s how I did it. (Please remember that you should do your own experiments before you decide that this is a good idea for your own projects.)

The formula:

1/2 cup cold water

1 cup Plaster of Paris

1/4 cup damp paper pulp

Adding Plaster to Cold Water
Adding Plaster to Cold Water

Measure 1/2 cup of cold water into a bowl and then put the 1 cup of plaster into the water and allow it to soak for a minute. While it’s doing that, you might want to go get a plastic bucket that you’ll need when you rinse out your bowl. Remember that plaster will get hard even under water, so you can’t rinse out the bowl in your sink.

Stir the Plaster Until Smooth
Stir the Plaster Until Smooth
Add Paper Pulp and Squish It In by Hand
Add Paper Pulp and Squish It In by Hand

You don’t want to use a mixer with plaster, because mechanical mixing causes the plaster to set up faster. You only have about 5 to 8 minutes as it is, so you certainly don’t want the plaster to get hard any faster than that. This part takes a bit of practice, and you might need to leave your pulp a bit wetter than usual.

When it’s all mixed, you can put the plaster/paper mix into the mold and spread it up the sides with your fingers or a small brush. I didn’t want my camera coated in plaster so I couldn’t get a picture of that part. I made my “skin” very thin – just enough of the mixture to capture the detail.

When the plaster is still wet but just starting to thicken, I placed a piece of cheesecloth over the plaster and used my brush to press the cheesecloth into the mixture.

Pressing the Cheescloth into the Plaster/Paper Mixture
Pressing the Cheescloth into the Plaster/Paper Mixture

I don’t know if the cheesecloth is really needed, but it seems like a good idea. I want the shell to be strong enough to hold up while the paper strips and paste are applied to the back.

The extra cheesecloth was then folded over, to reinforce the edges. By now the plaster will be starting to set up, and the shell can be removed from the mold in about half an hour. I’ll leave the pieces in a warm spot overnight to dry before finishing the backs.

You can see in the photo below that the plaster catches even the tiniest details. It also catches any flubs that might have been in the clay original, of course. (I forgot to add texture to the wolf’s eyebrow, for instance. Oh well, we can’t be perfect. There are a few spots where air was caught under the plaster, and I’ll repair these with paper mache clay.

Wolf Shell, Showing Eye Detail
Wolf Shell, Showing Eye Detail

I now have the shell of one hippo, one wolf and one mountain lion drying. The paper/paste backs will also take several days to dry, of course, so I won’t be able to start painting until next week. That gives me time to play around and make some more originals – it will be nice to get back to creating something again.

62 thoughts on “Paper Pulp and Plaster in the Silicone Molds”

  1. Hi Reese and Jonni
    I wrote a big post on using paper mache clay in silicone molds and freezing them some where. I have had good success. The main problem is that if you don’t use enough plaster in the mix there is nothing to make the paper mache clay hold its shape when it defrosts. I overcame this problem by first putting the papermache clay [no plaster] in the silicone mold in a rather thin layer. Than I put small squares of regular toilet paper on the back of the paper mache clay. What this does is pull enough moisture out of the paper mache clay to make it self supporting when you take it out of the freezer and dump it out of the mold. If you elevate the casting on a screen so air gets to both sides of your casting than both sides will dry. After that you can just peel off the now dry toilet paper or you can coat the toilet paper with starch or pva glue and add another layer of papermache clay.
    I also was able to fill a silicone mold with paper mache clay than put in the toilet paper pieces and than bake the silicone mold in an over at 150 f to dry it enough so that I didn’t need to freeze it. [freezing is safer-especially if you have undercuts]
    Unlike plaster paper mache clay only gets stiffer as it loses water.

  2. Came across your site while googling for how to “cast” with paper clay/mache in silicone molds. One idea I had but that hasn’t quite panned out yet, was to let the clay/slip (without plaster) dry as much as it will in the mold, and then put it in the freezer to make it hard before demolding, so that it could then dry out on the other side. Just wandering if you had considered this? My experiments so far have not been successful but I need to have a proper clay mixture first and a correct balance of clay/water so that when the water starts melting again it doesn’t leave the undried part in a puddle.

    • I haven’t tried that yet. The challenge would be keeping the pm clay supported as it dries, and that’s hard to imagine without the mold. If you figure it out, please let us know how you did it!

      • I will let you know. Just asked Aves Studio if ClayShay will dry in a silicone mold, and they say yes but I think I will have to freeze it to get the nose/brow/lips out as part of the whole…

  3. Really innovative thought to play with paper pulp and plaster to produce some amazing decorative masks, of course, there was a fair chance of failure but you yield some great result. Congrats!

  4. Hi Jonni
    I sure appreciate you sharing your different techniques with us. I just ordered your book ” Fast Faces ” and I should be getting it in about two more days. The thing is that my sculptures turn out pretty good but it is very hard for me. I figure I produce my sculpture more for the love of the finished product than the fun of making them. [I mostly make clocks and am a former aircraft machinist , I make my own clock movements] So it will be fun to just make some “fast faces” and possible enjoy myself more. My biggest problem is concentrating on the detail way too soon.

    The other thing I was reading about was the discussion about casting plaster and paper fiber in silicone molds and the trouble with the plaster setting up too fast. I have found a solution for this and I use it all the time. Two things work. The first product is called SODATE RETARDER, it is sold by many ceramic supply company’s. One of them is Laguna Clay in California and it isn’t very expensive. The other way to extend the setting time of plaster is to go to you nearest grocery store and buy some BAKING POWDER [not Baking Soda] and add some to your plaster before sprinkling it in the water. That will impede the setting time of your plaster quite a bit. Just mix in some Baking Powder into a batch of plaster. Maybe 1/4 teaspoon to about 4 cups of plaster. Than test a little of the plaster out. If it still sets to fast than add a little more Baking Powder. The only effect the Baking Powder seems to have on the plaster is to slow down the setting time. I have premixed batches of plaster with Baking Powder in them [kept the plaster in an airtight plastic container] and used the plaster months later and the plaster still works fine.

    • Bruce, your clock is absolutely amazing! Is it a plaster cast of your sculpture, with your hand-crafted clock inside?

      And your tips about slowing down the hardening of plaster are great, too. This is an old post and I’m afraid a lot of people will miss it. If you have time, you might want to copy and paste your comment (and include your clock, of course!) to the Daily Sculptors page. Many more people would see it there, because there’s a link to that page at the top of the site. I know your clock will get a lot of comments!

  5. Hi Jonni,

    This is such a great resource – thank you. I have a couple of questions, if you don’t mind. Would you ever use this paper pulp and plaster recipe for a mask that is meant to be worn?

    Also, have you ever used wood/carpenters glue in any of your pulp or clay recipes instead of Elmers/PVA? I often use wood glue when doing papier-mâché and wonder whether it’s worth trying.

    Lastly, I believe you mentioned somewhere that the pulp and clay recipes tend to shrink a bit when they dry. Any idea as to why this is, or which ingredient causes the shrinkage? Or is it just the evaporating water? I’m trying to come up with a batch that has little to no shrinkage.

    And have you ever tried leaving out the flour from the paper pulp recipe?

    Many thanks for all your help and this great site!

    • Hi Penny. I would not use the paper and plaster mix for a mask because it would be too heavy. It isn’t as heavy as you would expect, but I would still choose plaster cloth instead of this mixture, just to keep the mask as light as possible. However, if you make a lot of masks and you need to keep the costs down, you might want to experiment on your own. You may discover that I’m wrong – it’s been known to happen. 🙂

      I believe I did try Elmer’s wood glue once, and it didn’t work. The mixture of the glue and joint compound became rubbery because of an ingredient in the glue (probably boron, used to inhibit mold). However, other brands might work just fine. You can find out quickly if you have some wood glue on hand. Just mix up a small amount of the glue with a small amount of the joint compound. If it turns into little rubber balls, it won’t work. If it stays soft, it will work just fine.

      I think any water-based mixture will shrink as it dries, unless plaster of Paris has been added. Plaster is a common ingredient in commercial “instant paper mache” products, because it hardens quickly by chemical action, and then slowly dries without shrinking. My paper mache clay recipe doesn’t have plaster, so it shrinks. Not much, but a little.

      Some people have tried using powdered marble in place of the flour in the paper mache clay recipe to thicken it without adding the flour. I haven’t heard back from them to see how it worked. Other people say you can use the dry form of drywall joint compound, and that would also thicken it without the flour. I haven’t tried that myself. The fast-setting dry joint compound contains plaster of Paris, so you might need to work really fast before it sets up on you. They also have slower setting joint compound, too, which has less plaster.

      • Thanks Jonni!

        You were bang on – I tried wood glue and the result was a rubber ball. Oh well, worth a shot.

        I make papier-mâché masks, often in negative silicone moulds with paper strips, and am on the hunt for a pulp recipe that I can press into the mould that won’t won’t shrink or crack as it dries, or develop any mold over time (which is why I was asking about leaving out the flour). Basically I’m looking for a way to continue to work in papier-mâché but save some time, as the paper strip method is quite time consuming.

        My latest experiment is one layer of paper strips, and once dried, applying a couple of layers of your pulp recipe (minus the flour). I’m still in process but am hopeful!

        One more question – have you ever tried Spackle in place of the Joint Compound?

        Many thanks,

        • Hi Penny. I haven’t tried the Spackle, but I think someone did try it, and it worked. Don’t quote me on that, though. You’d want to get a small container and try it. I believe some of them contain the calcium carbonate that bonds to the glue (that’s what causes the paper mache clay to get nice and hard). I don’t think you’d be able to tell from the label, so you’d need to experiment a little.

          If you find an easy way to make paper mache masks in a mold, please let us know. We have several guest posts on the blog written by people who do use molds, but the process is really time consuming. However, Sarah is getting some nice detail with traditional paper pulp in plaster molds. Maybe some of her ideas would help with your projects, too.

  6. Hi Jonni,
    I linked to this post as well as your basic paper clay recipe in the booklet I just put together about oogoo mold making. Are you familiar with that method? It uses silicone caulk and cornstarch. My husband has been using it for 5 years to cast latex ornament for costumes. It’s easy, cheap and fast. I have done a few experiments with your paper clay in it and definitely want to try this plaster+paper pulp idea.
    Here’s the link to the booklet:
    If you would like a copy I’ll email it to you.

    one of your fans,

  7. Hi Jonni,

    Not sure if this is the correct thread for my question but I wanted to know if you have ever tried creating a plaster cast inside of a paper mache mold? I am creating a mask for Halloween. The sculpt was made with Klean klay. I was about to apply several layers of paper mache, using your fast setting paper mache recipe, and it occurred to me that if I could create a plaster cast of the mask sculpt, I could then make multiple paper mache masks, instead of just the one, which would then destroy the clay sculpture. What I thought I would try to do is make the paper mache mask (as I would be doing anyway), but then pour in some plaster of paris to create a plaster cast positive. Then I could use that to make several paper mache copies.

    • Hi Amon. This might work, but I do worry that the water in the plaster might get the paper mache too wet, and it might change shape before the plaster sets. Will you be able to seal the paper mache before pouring the plaster? If so, this should work just fine. Paper mache does stick to plaster, of course, so you would need to use a release on your plaster model when you made your copies.

  8. I am wondering if this technique/recipe will work with the plaster 2-part molds used for ceramics, if a release agent is applied first?

    • I’m not sure – you would have to be really careful to use a good release, and to have no undercuts. I’d do a small test mold first, just to see if it works. It would be challenging, but you might get some good results.

  9. Hi Jonni,
    You mention “paper pulp” as the ingredient for the paper/plaster mixture. I just wanted to confirm what you mean by this. Are you referring to your paper mache clay recipe, OR are you referring to actual paper pulp made of toilet paper that’s been boiled on the stove?
    I’m hoping to start a couple molds of some theatrical masks i’ve got on the go here, thanks to your bloggings about mold making, i’m all inspired!

    • Hi Sebastian. For these masks I used paper from some cellulose insulation – it’s just ground up paper, that has been softened with hot water. I’m sure that newspaper made into pulp using the boiling method would work, too, but you do need to get it fine enough so it mixes easily with the plaster.

      Good luck with your project. Be sure to let us see your masks when they’re done.

      • Hm ok =) Would you use toilet paper for the pulp or would newspaper be a stronger choice? Also, just another quick question, you said you made the original masks (that the molds were made from) out of water-based clay. Did you use a water-base clay that needed to be fired? Or did you just let it dry out a bit, then put on the sealer? I’d hate to buy the wrong type of water-base clay, as I know there are ones that air dry and I have no access to a kiln.
        Thank you for you’re speedy replies and wonderful tutorials!

        • I don’t know what paper pulp would be stronger – that would be something that you’d want to experiment with. The newspaper is cheaper, of course, but it’s harder to get it to “melt” into a smooth pulp. The clay I used is ordinary pottery clay, but I didn’t fire it. I just let it dry out a bit, and then sealed it so the silicone won’t be absorbed by the dry clay. The sealer doesn’t seem to hurt the clay, and I am able to use it again for another project. I don’t have a kiln, so firing clay isn’t really an option, anyway. You could also use a plasticine clay, as long as it doesn’t contain sulfur, but it’s more expensive.

          • I have found that it is possible to get the newsprint into a *smooth pulp*. . .
            Easy directions: Shred paper & use scissors to cut up the long strands.
            – Put in a bucket, Add enough Boiling water to cover 1/2 way.
            -stir up & fill to cover the paper with (room temp.) water.
            – Allow to set a few hours or over night.
            – – Blend small amounts until smooth, adding water to the blender as necessary. . . dump into another bucket or bowl, while blending the next batch.

            I make paper sheets & use some of them as *strips* for my mache’ projects, as well as using the pulp for molds.
            Hope this Info helps someone.

      • It finally did lol It finally did.

        In case anyone read the existing post please note i ‘amended’ one of the measurements – The previous 9 desert spoonfuls of PURE PVA ‘now’ reads: 4 ounces/100gms (NOT FLUID OUNCES) PURE PVA (white latex based) glue.

        Sorry lack of sleep.


  10. Okay i put together a second experimental batch of my White Matter© today. At this point it is some two hours and seventeen minutes in and it is working just as the first batch did as in it is not going off (hard) in the mixing bowl. I ‘definately’ have cracked the secret of retarding the plaster of Paris going off too quickly. However, i made some slight changes to the tissue paper content this time to see what would happen.

    In the first batch i made the mix was approximately forty percent tissue paper to sixty percent plaster of Paris plus ingredient ‘x’ which i will reveal later when i know i have perfect results every time. Now as i have said it is staying wet and completely useable as the first batch did, however drying times in the moulds has increased dramatically and in some moulds there is serious shrinkage. Water is pooling in the lower hollow regions in the moulds too.

    I have been aiming at getting the mix to a fifty percent tissue pulp and fifty percent plaster. This it appears will simply not work. Not with as fast in the mould drying times anyway. The shrinkage i ‘think’ is due to the ‘increase’ of water which is being introduced along with the increased tissue pulp levels ‘not’ the tissue itself. Now don’t take my word on that yet. I am still only working from personal theories here and they are best sketchy at this point. I am still working out the reasons ‘why’ this mix works as it does. Plaster after all ‘will’ go off no matter how much water you add. It will take longer of course but it ‘will’ none the less seprate from the eccess water sink and go off under the water. This consistant reaction is how you clean your containers after use after all.

    To clean mixing containers you want to reuse simply add water to the container you were using. Use a paint brush, cloth or sponge to wipe down the sides of the container with the water in the container. Then simply place the container somewhere it will not be disturbed for a day or two. Later go back to it to find most of the water has evaporated leaving a solid block of plaster at the bottom of the container. If you have no use for this plaster simply dispose of it as your local waste management authorities advise. Or you can break it down with a hammer, oven bake it dry. Run it through a coffee grinder etc, voila re-useable plaster again.

    When it comes to using the new batch on existing plaster/White Matter© objects IE: previously made skulls there is ‘no’ change to the way the mix reacts as with the first batch. In this respect the results are identical. In fact i am currently using it to join up the halves of the plaster skulls i made yesterday. Not only are the two halves bonding beautifully, seamlessly. The new batch of White Matter© is acting exactly as the first experimental batch did in this instance.

    I still have another twelve skull halves to build up today which is going to take me up to my time to quit for the day. I will make a third and i am sure final experimental batch tomorrow with a reduced tissue paper content matcing the first batch which should fix the increased drying times and shrinkage issues i created with toady’s experimental batch.

    So to round off for today not total perfect results but i did throw a spanner in the works by increasing the paper content. Then again this is all part and parcel of experimenting is it not lol.

    More soon.

  11. I will be repeating the experiment today (in a few hours from now) i am confident, but then these things have a habit of working just to taunt us then blowing up in our faces lol. Here is hoping though.

    Oh i wish it were a migical ingredient i assure you. It might have been esier to see it & reach out for it as it was in front of me the whole time lol.

    More news soon, including the recipe if i can make it work again.

  12. Hi Jonnie & readers,


    Okay just let me calm down a second…

    Now for those who have been following my blog and my posts here, especially my attempts at making a viable plaster and pulp sculpting medium you will know of my semi successes and failures so far. Just the day before yesterday i posted on my latest failure. Okay yesterday i cracked the recipe.

    I have created a plaster of Paris and tissue pulp medium that bonds to several mediums which paper mache artists currently mainly use. My plaster and pulp medium can be sculpted on or over existing creations and armatures without any prior preparations these being dry: plaster, clay, pulp, news paper, white printer paper, telephone directory paper, card stock and even wood.

    My previous attempts at making this medium met with mixed results among which was a varying working time frame which ranged anything from eight minutes to fifteen minutes before the previous mediums dried out and became un-workable. On my blog is a short video of my latest and successful medium. Watch the video and see if you can guess the current life span of the medium in the video. Oh i apologise for the darkness of the video it was late, i was sore and tired. I did not think to check the lighting quality before shooting the video – Sorry.

    So care to take a guess at how old this mix is then at the time of shooting this short video?

    1: five minutes?
    2: ten minutes?
    3: fifteen minutes?
    4: twenty minutes?
    5: thirty minutes?
    6: one hour?

    Keep guessing.

    keep guessing.

    Keep guessing.

    Keep guessing I will tell you in a minute.

    Keep guessing.

    Go on one more guess.

    The medium you just watched me playing with in the short video is at the time of shooting the video was in fact two hours and eleven minutes old. Directly after shooting that video i made the following skull you can see on my blog as well as testing it on the other mediums i mentioned above.

    The skull in the foreground (on the right of the picture) is the one i made with my new plaster pulp medium. The skull in the background is a pure plaster skull i made days earlier. As you can see the new plaster pulp mix when dry can easily be carved/sculpted using a craft knife. It looks and feels just as strong as pure plaster and can easily be smoothed out to a very smooth finish no matter how you use it. Here it is direct from a latex mould however.

    I did not use up all the plaster pulp mix in fact i wanted to know just how long it would stand before drying out and becoming too hard to work with. If you think two plus hours working time is unbelievable your not going to believe me then when i tell you that ten hours later the plaster pulp mix shown in the video was ‘still’ as fresh as that shown in the video. At that point i got tired of checking it every ten minutes and simply spread it out in the bowl and micro waved it for three minutes before going to bed.

    So now there is one question still to answer. Can i remake this batch, if so will it work in the same way?

    I will get to it in a few hours, run some tests then get back to you after the weekend on that one. Yes before anyone asks i WILL be giving you the recipe for this just as soon as i know if i can repeat the mixture and have the same results.

    More soon

    • That looks really interesting – I can’t wait to see if you can repeat the experiment, and if it turns out as well. You must be using some magic ingredients to allow you to play with it so long.

  13. Hi Jonni/readers,

    Well below is an update (from my blog) of my latest experiments on my plaster pulp mix. I know these results are going to suprise you Jonni & some of your readers too they certainly were not what i was expecting especially with the linseed oil.

    My first plaster pulp experiments using ClayCrete a commercially purchased ready prepared mixed pulp were a total success. I forget how much amount wise you get per bag a couple of pounds or so at £10.00 GBP, Not a lot if your making large or numerous projects. However not knowing what the binding agent is in the commercially purchased product leaves me stuck in re-creating the same results it gives with home made recipes – for now at least.

    My home made pulps for use in my other earlier plaster pulp experiments were a success also in that they formed perfectly in the moulds copying the details of the moulds & were near enough strength wise to both suit my needs & being close enough to the commercial pulp. How ever as i have said the ‘core’ of the casts i made using my home made pulps were not bonding with the plaster enough to make them viable.

    My new plaster pulp recipe has the exact same flaws, though my armature method of mixing this plaster pulp version if nothing else not only confirmed my previous theories but also reinforced them. I want the mix to be as close to 50% plaster & 50% paper pulp as possible keeping it in the acceptable standard PM constraints & allowing it to be rightfully classified as a paper mache product. So my theories, discoveries & conclusions so far then.

    WHITE MATTER Ver. 1©TM J Jones

    POSITIVE POINTS (Air & radiator drying)
    Created using commercial ready made pulp: 100% success. extremely Light weight, strong throughout, fast drying. Can be carved/sculpted using sharp tools.

    The commercially purchased ready made pulp IS expensive & comes in small amounts.

    GREY MATTER Ver. 1©TM J Jones

    POSITIVE POINTS (Air & radiator drying)
    Created using home made news paper based pulp 70% success, extremely light weight.
    Soft inner core. Plaster & pulp not bonding leaving it susceptible to breaking easily.

    GREY MATTER Ver. 2©TM J Jones

    POSITIVE POINTS (air & radiator drying)
    Created using home made news paper based pulp 50% success, extremely light weight, strong outer shell finish, fast drying. Can be carved/sculpted using sharp tools if some what cautiously.

    Soft inner core. Plaster & pulp not bonding leaving it susceptible to breaking much more easily.

    GREY MATTER Ver. 3©TM J Jones

    POSITIVE POINTS (Air & radiator drying)
    Created using home made news paper based pulp 40%/50% success, extremely light weight, strong outer shell finish, fast drying. Can be carved/sculpted using sharp tools if somewhat cautiously.

    Soft inner core. Plaster & pulp not bonding leaving it susceptible to breaking much more easily again.

    WHITE MATTER Ver. 2©TM J Jones

    POSITIVE POINTS (Air drying)
    Created using home made toilet roll tissue paper based pulp 20%/30% success. If plaster 70% to pulp 30% ratio. Extremely light weight, moderately strong outer shell finish, fast drying depending on water content. Can be carved/sculpted using sharp tools with care.

    NEGATIVE POINTS (Radiator drying)
    Too much water: Can take 48+ hours to air dry. Extremely difficult to work with even in a mould. Soft throughout surface to inner core with a soft outer paper like pulp like shell. Plaster & pulp not bonding, Shrinkage EXTREME. Cracking & crumbling when handled.

    Too much pulp: Dries too slowly, Soft throughout surface to inner core with a soft outer paper like pulp like shell. Plaster & pulp not bonding. Shrinkage EXTREME. Crumbles when handling.

    Too much plaster: Dries too quickly, medium hard surface & core. Plaster & pulp slightly better bonding. Shrinkage varies. Crumbles when handling though slightly less so.


    With exception to the water, pulp & plaster ratios the ‘same’ main problems as in the original home made pulp versions. The plaster & pulp not bonding sufficiently enough. Adding raw linseed oil contrary to positive research had NO noticeable effect in ANY positive way. Indeed giving pre-made plaster moulds two coats did not strengthen the already hard dried plaster. In fact they became softer. Before painting on two coats of linseed oil the plaster moulds had an extremely hard ceramic like surface that i could not mark with my fingernail & have to when required carve/sculpt with a craft knife. After coating in linseed oil & leaving twenty four hours to dry out i could easily scratch the surface & a little deeper with my thumb nail.

    Using toilet roll tissue instead of news paper pulp did make mixing the ‘wet’ pulp & plaster much easier, so a positive point there. However my original recipes are based on ‘dried’ pulp ratios. The wet tissue pulp offers up it’s own problems in calculating the weight to content ratios for a more accurate recipe since water content of the tissue pulp can & will alter from batch to batch. Something to ponder there for sure.

    Substituting the original news paper pulp for the tissue pulp HAS positive advantages i am in no doubt. Certainly in mixing & dry weight, probably even in account of strength too. The problem remains constant however when it comes to achieving a bond in the core of the mix when dry. I have a ‘potential’ solution in mind, but this brings with it its own potential problems too.

    PVA glue (Elmer’s etc) or more specifically the type/brand i use is well known for its bonding properties. Indeed its used widely in the building trade when plastering old dry walls where old traditional lime based plaster would have once been. A coat of watered down PVA glue directly on the wall allows the new modern plaster to bond to the old stone work. So theoretically it ‘may’ make the plaster bond to the paper pulp in this case?

    The potential problems then being PVA glue(s) & liquid latex moulding solutions have one key ingredient ‘latex’. It has to be assumed of course that it may vary in amounts & strengths in each product i know from experience that a torn latex mould can be repaired if torn etc with pure PVA glue, ie: They bond readily & strongly!. So now the question is how much is going to be enough to create a ‘potential’ bond between the plaster & the tissue pulp without being too much & bonding with the latex mould?

    Another thing to consider here of course is joint compounds. Of which there are many versions & again like the linseed oil joint compounds have received a lot of positive press. Of course there remains a singular issue throughout the whole of this experiment that cannot be ignored. We all be we in different counties or countries have different grades of papers, glues & compounds be they joint, latex or wood based. What work for one person in one region may not work for another elsewhere?

    At the very least i can hope for is gaining the right working recipe that suits my needs that other ‘may’ be able to use too or at best if not a working recipe for others then a starting point that they can use to find the solution for themselves in this area at least.

    You can see a couple of pictures of my latest er!, failures on my blog at the bottom of this article:

    As to my own side of things the experimenting continues.

    More soon.

  14. Hi Jonni & readers,

    Well i finally got around to working on a new plaster pulp mix today. I actually started yesterday but today was the mix i wanted to make properly. Hmm!, better explain this a little better i think.

    After your suggestions Jonni ‘for’ using linseed oil & some research of my own i purchased some online a few days back, two 500ml bottles to be exact. I didn’t buy it for the extra hardening properties alone however, no. The outer hardness of my own plaster pulp experimental mixes was not the issues i was having. It was the bonding of the heavier paper pulp i was using. I am hoping the softer thinner tissue pulp will absorb some of the linseed oil & then harden with it being there. Then hopefully it might bond to the plaster a little better in the ‘core’ of the mix. The linseed oil only arrived today however. Yesterday i thought i’d mix up a batch (many small batches as per requirements during use) as a comparrison to todays mix containing linseed oil.

    The new batch is a slight variation on your variation of one of my original mixes. This could get very confusing i think if were not careful lol. Anyway i am using raw linseed oil unboiled. In my original mixes i carefully measured out specific amounts of all the ingredients. The original mixes were large batches of around 4 ounces. This time however i am working to smaller molds so i have been making them at around 1 ounce or so batches measuring the ingredients by the spoonful basically. My current experimental plaster pulp goes as follows:

    1: 4/5 desert spoons (depending on mold size) of very wet toilet tissue pulp (as from the blender very water logged wet).
    2: 1 capfull of raw linseed oil unboiled mixed directly into the wet tissue pulp.
    3: additional water as required just prior to adding the plaster.
    4: aprox 1 to 1 & a 1/2 ounces of sculpting grade plaster mixed together to form a runny porridge like paste.
    5: This i then mixed until it began to thicken (go off) at this point i split the mix between two or four molds depending on the size of the molds in use at the time using a small flat bristled paint brush to apply in the molds. I have not used any supportive mesh cloth at this point. Primerily as i simply don’t have any to hand. Its not something i can’t seem to find easily locally.
    6: If required some molds were ‘patched up’ were the mix had slid from the rim or edges of some of the molds becasue of having to work quickly.
    7: The molds were then left to air dry for the next couple of days.

    At this point i am 50/50 hopeful & sceptical this particlar mix is right. Some of the mini batches dried hard to the touch minutes after going into the molds even if i applied the mix when still very runny. Some remained very wet more than 2 hours later. I feel this was simply due to sometimes each spoonful of tissue pulp came with more water on the spoon than others. Also sometimes a little more plaster than other times went into the mix. I think i might have to drain the tissue pulp next time & measure both it & the plaster a little more acurately for a more consistant & better working mix to prevent these dry & wet irregularities in the same mix. Mot the best scientific method of experiemtning using the rule of the thumb, but then it has been a bit of a crazy day for me.

    I don’t know why at this point but my original working times ‘after’ mixing has been radically reduced from 8/15 minutes to worst case sinario litterally 1/2 minutes after mixing. Could be the change from heavier paper to tissue paper, or the slight irregularity in the plaster amounts i am adding. Hmm!, more than likely the latter i think.

    So to draw this post to an end for now. I have made a host of castings up: mini skull trophy/candle sconces, new slightly bigger realistic skulls (can be seen on my blog) to the first casts of my ouroboros project. I will let you all know how these batches went once they are all fully dried & de-molded in a few days.

  15. For the first experiments making the plaster pulp hybrid mix i decided to stay with just that to give me working examples of mixes that i knew would work to some basic degree, a starting point if you like to think of them that way. working with a commercialy produced pulp gave me the perfect example/comparison to how good my own home made pulp(s) are. Whilst i got good working results obviously they weren’t as strong as i require later. They will produce a working plaster/pulp mix that most others ‘can’ use if not as stand alone mixes for sculpting via molds or free hand sculpting. They will definately give good results from molds which is the direction i will be going with & intended my final versions for when i get that far.

    The test batches i made didn’t so much have any ‘hardness’ issues in fact they were perfect in that respect it was more a case of the pulp & plaster binding or bonding together i as most people experimenting with this mix will find.

    Ah yes using high pressure presses would most definately resolve the bonding issue lol but then your talking very specialised custom designed presses there which you would have to re-design & make for each new project lol. Remember most if not all of what i do & show on my blog is orientated towards the more frugal artists be that by choice or unavoidable low funds. If it can’t be produced at home or purchased relatively cheaply then it defeats the purposes of my blog lol.

    If you want to dry large ‘flat’ sections of any project i do have a simple soloution. Thin cardstock or nore notoriously annoying corrigated cardstocks are the worst for warpping during drying. A simple soloution is to pre-work the cardstock first by covering it with 2/3 layers of paper strips on both sides. Take two sheets of plastic (carrier bags/bin liners etc) & sandwhich the cardstock inbetween the plastic. Now take 2 pieces of flat wood (wood chip, ply wood etc) & then sandwhich the plastic covered cardstock inbetween the pieces of wood. Gerally (depending on the wood used) the weight of the wood alone is enough to press & hold the cardstock flat whilst drying. Of course because the air is not passing over/around the wet cardstock it will take much longer to dry. Then again of course you will have a much stiffer section of cardstock even using corrigated cardstock to work with in the actual project(s) your working on.

    All final results for my plaster pulp mix(s) will be posted on my blog & of course will be made public here & anywhere else i happen to post on/in for sure lol.

    Hmm, linseed oil whilst being an excellent natural wood presservative is well known for being a drying retardent for many aplications/materials. Its use is more commonly known in traditional glaziers putty for use as window sealer of course many silicone substitutes are more widely used today. Personally i feel using it in ‘any’ pulp(s) would have to be done with much caution as use too much the pulp would most certainly slow down the drying process at best. At worst it would promote mould in the wet pulp deeper core, reduce/prevent glue adhearing properly not to mention water based paints too. Linseed oil, not a direction i will be taking. At the same time i am not saying don’t, just its not for me.

    The link/blog article is on my blog right now. I posted it right after posting here earlier lol.

    I got my store up & running a little while back now. You can find it here:

    Lol along with my Troll Screamers the store was intended for other items too of course. Sadly as hard as i make anything for both my blog tutorials or my YouTube tutorials which are listed on my blog (70+ videos now), in the file section of PMA the group Jonni mentioned. I will be compling them all onto DVD’s for sale for those who do not have high speed access & can not download them to watch soon) those of my children still living at home tend to be wreckless around what i make. A long story short around 90% of what i make ends up broken & never reaches the store sadly. I am working on new tutorials & items for my store & have taken steps to prevent careless remaining family members from wrecking the new items lol.

    Getting traffic to any page be it a blog, website, Etsy or Ebay store can be a tricky subject. Most online places such as Etsy, Ebay etc will give you many many hints & tips or even theyre own versions of advertising features. ie: through theyre own advertising galleries, blogs or RSS feeds & Email notifications etc. Of course you can also help things along by using TABS. These are simply key or identifying words that link either directly to ‘your’ site, page or section of an article etc.

    As you said Jonni links are good. The only way your going to get anything noticed be it a website of specific page on an online store etc is by working at it. Tell your friends about your store/page. Ask them to spread the word (link) around. Such as in Etsy (everything gets displaid up) front, Go to other ‘similar’ artists stores. Either link to theyre stores or specific items they may be selling. 9 out of 10 people will return one or both the favours. Add links to your store on your websites, blogs etc.

    Create a Flickr account & create an animated display box for what you have in your store to place on your website, blog or use the HTML code you’d use on your own sites as an exchange button etc between friends etc.

    Then of course in the end none of this is worth even thinking about unless you are prepared to update all or as much of this information as & when required, check broken links etc. Dead or out of date links & pages are guaranteed to kill any return visites or repat searches stone dead.

    Basically its all about getting noticed & ‘keeping’ peoples attention. The internet IS a fast paced constantly updating system. Throw into the mix the fact there is so much to be seen people easily get bored & will move on to new pastures. You have to stop them from getting bored & keep theyre attention!.

    • Your advice for an Etsy store is very good, Jonty. You’re truly generous with your expertise. And I look forward to more of your experiments. I did a very non-scientific experiment of my own this morning, by adding cornstarch to one small batch (did not increase working time) and white flour to another batch (increased working time, lots of bubbles in both batches). Then I added a small amount of linseed oil to a batch with flour, about 1 teaspoon of each item to a mix containing 1/2 cup of plaster, and it got rid of the bubbles. It still set up, but I don’t know if it will remain soft, as you hinted. I thought I was all through experimenting, but I seem to be in the mood lately. Don’t know why.

      • Ah but can there truely be a non-scientific experiment? I think not.

        Oh don’t get me wrong a small amount of linseed oil will inevitably be ‘lost’ in the large mix of other materials used. However i don’t want to both use it myself or encourage others to do so. It is all to easy to say something in passing & it be taken out of context because someone didnt fully read the instructions given or loose terms used, for instance i say experiment with linseed oil & then someone is halfway through a large or beautiful project. They change or try a new recipe to finish off theyre project & then BAM!. They ruin it. I neither want that nor to be branded for giving false or stupid advice.

        Saying that i am not saying dont try it if anyone feels it benifits as particlular pulp mix. It can not be ignored that different mixes both suit different techniques & sculpting methods. Of course everyone has theyre own personal favourite mixes too.

        Two things i forgot to mention in my last post:

        1: The normal proceedure to remove trapped air which is unavoidable whilst mixing ‘any’ type of plaster is to pour evenly into the selected mold then gently tap the mold as one on a hard surface – firmly but steadily. The air will form bubbles & work its way to the surface. When the bubbles ‘stop’ rising chances are that you have removed all the air trapped.

        2: When mixing plaster pulp to ensure a more even mixing of the plaster & pulp mix the plaster & ‘dry’ fluffy pulp first using a knife, a spoon, a stick etc. Then & only then add the water in one go. Mix thoroughly for a minute or so following point 1 at this time.

        Just prior to adding the plaster pulp to the mold gently squeeze the plaster pulp between your fingers in small amounts to remove any ‘potential’ trapped air that may remain since the mix is now much thicker. When presenting it to the mold use your finger(s) or a small tool to push the mix into place firmly but not excessively.

        For best results work it in the mold to around 1mm layers ending up with around 2mm/3mm which gives a good solid form, keeps weight & drying times down to a minimum. Obviously large projects will require thicker ‘shells’ but always work in layers as stated above for best results. For best result allow each ‘new’ layer to fully dry before applying the next. Always ‘air’ dry for a few hours ‘near’ NOT on a heat source to reduce shrinking or warpping. Then you can place directly ‘on or over’ a heat souce (radiator etc) over night for speedier drying.

        When appying a ‘new’ layer lightly wet the previous layers surface with a watered down mix of PVA glue & water (milky consistancy) & apply the next layer before this dries, don’t soak it!. If you don’t have any PVA glue (or Elmers etc) just water will do but you will need to apply just a ‘little’ more pressure than with the PVA method.

        Lol definately ‘more’ experiments on the way. I have a few skulls to work on just now. My grunge skulls. Not comical styled but not quite realistic. Some very large skulls but more about them later (on my blog) & some realistic skulls that are around 80% accurate. This weekend though i want to do some work on something i have been planning for quite some time but i could not find just the right sized circular mirrors until Tuesday gone on my latest art supply run. Some 19 inch mirrors with two types of Ouroboros’s. One traditional snakes. The other – Well thats a wait i see lol.

  16. Why thank you Jonni for the mention very kind. The first test mix/batch i used a pre-mix commercial pulp more for comparision in my own home made pulps than anything. Since the commercial pulp requires only water & comes with a grainy heavier material incorperated its obvious they are using something other than wall paper paste or the like in there. From the colour of the fine grains & the texture i am assuming it to be dried starch they are using as the bond for the pulp which is a perfect & more often used bonding agent. All my test batches/mixes can be found on my blog.

    In the post i mention i’d be experimenting again for the perfect mix. When i do i will be trying some dried starch as soon as i can find where to get some. From past experiments & assumptions i feel dried starch is the missing ingredient to making my plaster pulps work with my home made pulps as the commercial pulp mixed with plaster gave oustanding results.

    The key to drying times & working times for the plaster pulp mixes i list is of course water. more reduces drying times but give longer working times. Less speeds up drying times but reduces working times. Saying that i was averaging min: 10 minutes working times to max: 15 minute working times working with a 4/6oz batch a time. I reccomend you make no more than a 40z batch a time or your going to have more mix going to waste before you can use it up.

    Definately working in ‘layers’ is the best method this way you can control the final thickness of the end result.

    Adding a couple of paper strips layers WILL add to final dry strength, but i think by adding dried starch to the mix WILL give ALL the final strength ANY project will require as long as the projects thinnest regions are no less than say 3mm thick. Of course domed or rounded shaped projects WILL retain theyre own unique strength from theyre final shape(s).

    Again thank you for the mention. I often get told that people are trying out what i show them but ‘rarely’ get to actually see any working or finished results. Great stuff keep it coming lol. I will (time permitting) post a mention & link back here on my blog if thats okay?

    • Jonty, have you tried corn starch in your mix? I read somewhere that adding starch will increase the working time, but I have not done experiments to see if this is true. You have a much more scientific mind than I do.

      According to this page on Victorian papier mache, their architectural doodads were made with paper, (the left-overs from rolls of wallpaper), gypsum (plaster), and starch. I think they could use a lot higher percentage of paper because they pressed the mixture into the molds, probably with a hydraulic press or something similar. (My interpretation – I may be getting this wrong). Then they soaked the pieces in oil, most probably linseed oil that would be a byproduct of the linen industry. When the soaked pieces were dried the result was supposed to be as hard as hardboard. The gypsum seems to be the trick for keeping the drying pieces from warping – something that seems impossible when making anything that’s flat.

      If you do find some starch or try the cornstarch, I would love to hear how your experiments come out. I once called our local mold supply company and they suggested that plaster will get much harder if you add a bit of Portland cement – so that might be another option. Somehow I don’t think most of us are going to be excited about soaking the pieces in linseed oil, since it’s pretty expensive, but we might experiment will including it in the mix.

      And yes, I would much appreciate a link – links are good 🙂

      By the way – I seem to recall that you were intending to start an etsy store for your screamers. Did I remember that right? If so, do you have any advice for others who might be thinking about doing that? I’ve heard that the hard part is getting traffic to the right page.

    • Jonty, have you tried methylcellulose? You can purchase it under the name of Elmers Art Paste. I bought some, but I didn’t notice any difference in my PMC.

      • No, nor am i going to. Apart from using PVA glue & foil for bulking (which i remove as much as possible during construction) & shaping i am both trying to keep my PM as traditional (nor do i use wire or large wooden frames) as possible only using recycled cards & papers etc that can be found around the home for the artists out there who may have limited funds. Remember PM has been around for some 2,000 years now Apart from flours & root extracts PM exsisted & lasted a long time without many of the modern day glues & derivertives.

        • I totally agree on recycling and using inexpensive ingredients! In fact, I started making my PMC with recycled junk mail, bills (after they were paid), and brown paper bags.

  17. Jonni, did you experiment with using more paper and less plaster? Just wondered if that would be lighter. I’m thinking about making a mold of some of my favorite ooak paper mache santas. I know you sculpted your animals from clay for these molds, do you think a finished, painted paper mache sculpture would be damaged during the mold making process?

    • Maggie, the shell is so thin that it’s extremely light. It’s also still quite fragile, even with the cheesecloth. It has to be backed with the paper mache, which will probably be heavier than the plaster shell.

      The package instructions for the silicone mold material say that it doesn’t usually harm the model, but do a test in a hidden place just to make sure. Are you the designer of the figure you want to copy?

      • Hi Jonni, yes, I am the designer. If I get the silicone mold material I can test it on a smaller piece that I made that I’m not happy with. I was also looking at a mold making material that you melt in the micro wave. It can be used over and over.

        • When I asked if you had experimented with more paper and less plaster, I was referring to the mixture that you pressed into the mold first. I was wondering if you had tried a different ratio of plaster:paper.

          • I did try using more paper, but the results weren’t very successful. The spaces between the paper bits don’t fill up with plaster, so you end up with a lot of voids on the surface of the piece. However, it might be possible to add more paper if the pulp is ground fine enough. As I mentioned to Jonty, the Victorians were able to use more paper in their mixes, but they probably used a press to force all the air out of the pieces. Another thing that might work is a vibrating table, to jiggle the air away from the mold.

        • That microwave stuff sounds interesting – do you know what it’s called? When you say you can use it over and over, do you mean you can remelt it and use it for another sculpture? (I’m glad you mentioned that you’re the designer – I wouldn’t want to think I was encouraging people to make copies of someone else’s work. We’d love to see your Santas – do you have a website?)

          • It is called Composimold. Here is the website:
            Yes, you can remelt the mold and make a new one. I was thinking of making a very limited edition of maybe 15 or 25 of each Santa. So this would save money on molds. I wonder if anyone here has tried it?
            I don’t have a website. I haven’t taken any photos of my Santas because the only camera I have at the time is on my cell phone, and I don’t know how to download them to my computer. I guess I’m technologically challenged! I do have a few photos that my granddaughter took on her camera when she visited a few weeks ago. The lighting isn’t good and she caught the mess on my table in the photos. But, I’ll try to figure how to upload them so you can see them. I’d appreciate any critiques.

            • That looks like interesting mold material. I’ll have to spend some time reading their website. I haven’t used it, but perhaps someone else has some experience with it.

              We would love to see your Santas. But I do understand the technical issues – I have plenty of those, myself. 🙂

            • Jonni, I checked the MSDS on the composimold and was surprised to learn that it is made from glycerine and gelatin. So then I googled glycerine and gelatin molding materials and found this recipe for flexible molds:


              Sounds like a huge amount, and I don’t know where to get flake gelatin. But, it is interesting.

            • If your phone is relatively new it should have come with a cd? Some don’t but have the USB cable in the packaging this means the software to tranfer the information from your phone is built into the phone & does not need to be installed on the PC.

              Load the cd (if you have one) then install as shown on screen.

              Connect your phones: phone to PC USB cable then run the installed software most kick in automatically when running in the background (on your bottom screen task bar. Search in the on screen ‘MY PHOT’OS’ section of the menu displaid.

              The photos should then be displaid just like on your PC in a folder or as a list of assigned incremntal names depending on your softweare supplied with phone this varies of course but the principle remains the same.

              Simply darg & drop all the pictures to an assigned new folder. Most modern phones will work with the PC & write the files as Jpeg or Jpg type if not again most modern softwat (art programes) can handle the files converstions easily enough.

              From this point on follow any group or blogs online uploading software or simply Email to the intended recipient (ie: Jonni) as an Email ‘attachment’ file – Voila’.

              Lol I know that reads like it is very complicated but trust me do it once & you can call yourself a PC techy just like that lol.

            • OOPS, good advice Jonty, except for one thing. I prefer that you post your images here on the blog instead of emailing them to me. That way, everyone can see them – and I don’t have to do all the resizing and uploading for you. Also, I don’t have to worry about opening an email with an attachment, something that I feel very uncomfortable about since so many people don’t have good anti-virus software on their own computers. You never know….

              So – follow Jonty’s instructions (I assume he’s right, but I don’t have a cell phone so I just have to trust him 🙂 – and then resize your images so they’ll fit into a column on this blog. That would be 400 pixels or less. Most photo editing software programs let you save for email or save for web, which gives a smaller file size. Then follow the instructions here to upload to your comment on the blog. I know it’s more involved than it used to be (WordPress changed things on us) but it’s still not that hard.

              I do sometimes get photos that have not been edited. If they were posted full size, some of them would take up the entire computer screen and you’d still only see a small portion of the image. These are photos that were uploaded straight from a camera, without editing. They look like they’re a reasonable size when you look at them on Imgur, but that’s because their program automatically reduces the size on the screen. Once they’re posted here, all you can see is an eyeball or an ear, and the rest is hidden.

              I used to edit them myself or do some html fancywork to make them look smaller, but I think I need to get tough on this subject because it slows down the pages for everyone. If you have a camera and the software, please get out your manual and find out how to make the images 400 pixels or less. It’s really not that hard, honest. 🙂

            • Hi Jonty,
              My phone did come with a CD and a cable… I moved and I can’t find the CD or the cable. I’m sure I unpacked everything it could be in. Only boxes left are craft stuff, in my “craft storage room”. Or, as my son calls it, my “crap room”. I’ll try looking for it today, thanks for the suggestions.

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