Making Silicone Molds – for Paper Mache Experiment

Favorite animal patterns from ultimatepapermache.comNote: If you’d like a faster way to create an animal wall sculpture, check out my patterns. Cut, tape, and cover with paper mache. You can find all my patterns by clicking here.

I’m writing this right before Christmas, and this is the time of year when I get the “what would happen if?” urges. That’s why I’ve been testing various minor additions and changes to the original paper mache clay recipe, hoping to find one that will work well in a mold. I previously tried using the original recipe in molds, and I couldn’t get a predictable result. So – back to the drawing board.

After getting every bowl in the house dirty, and filling my garbage bin with rejects, I think I have now found a recipe that will work better in molds.  I’ll post the recipe when I know for sure.

To test the new recipe, I made two molds using Rebound 25. Last summer I made molds using urethane rubber, which is messy – I was hoping that the silicone would be more fun to use, and so far I’m quite happy with it.

I built two models using water-based clay. The wolf and cougar were allowed to dry, and then I prepared them for the mold silicone by sealing them with a product called SuperSeal that I purchased from Farwest Materials in Walla Walla.

Silicon Mold for Wolf Wall Hanging, Step 1
Silicon Mold for Wolf Wall Hanging, Step 1

You can see that I designed the shape of the wolf wall hanging so that I could easily reach all parts of the mold from the other side. The paper mache clay will need to be pressed in by hand, and a lot of pressure will be needed to get all the details. The sealer prevents the silicone mold material from entering the dry clay, which would ruin the mold.

Rebound 25 Mold Material
Rebound 25 Mold Material

The next step was to mix up the Rebound 25, a silicone product that is mixed 1 to 1 by volume. I should also have purchased some Thi Vex, a product that will thicken the silicone for the second and third coats, but the supplier had run out temporarily. I hoped that I could make do without it. This was a mistake, because the liquid rubber flows off of any high spots, leaving them very thin, regardless of how many coats are added. The rubber over the wolf’s eyelashes are very thin, and the thickener would have prevented that. Oh well – live and learn…

The starter kit, shown above, was enough for both the wolf and the cougar, with about 1/3 left over for another project.

Silicone Mold for Wolf Wall Mask, Step 2
Silicone Mold for Wolf Wall Mask, Step 2

You can see how thin the rubber is when you paint it on the model. This is perfect for the first coat, because it catches every detail. For later coats, it really should be thickened with the Thi Vex stuff.

Silicone Mold for Wolf Wall Hanging, Step 3
Silicone Mold for Wolf Wall Hanging, Step 3

The mold rubber dries for about 1 hour between coats. You can see in the photo above how it tends to drip and move to lower spots when the thickener isn’t used. The photo above shows the wolf after 4 coats have been added, and it’s now curing. I allowed it to cure overnight.

Silicone Mold for Wolf Wall Hanging, Step 4
Silicone Mold for Wolf Wall Hanging, Step 4

When the silicone has cured it’s time to make the mother mold. I wanted a mother mold that’s lighter than poured plaster, because I’ll probably be holding the mold in my lap while I press the paper mache clay into it. I decided to try using the plaster-impregnated gauze, which I have never tried before. This is how wolf looks after several layers of bandage have been added, with extra gauze put on around the edges and over the ears. I let it dry for several hours while I made a run to the store to stock up on dog food.

Silicone Mold for Wolf Wall Hanging
Silicone Mold for Wolf Wall Hanging
Silicone Mold for Cougar Wall Hanging
Silicone Mold for Cougar Wall Hanging

I made the mold for the cougar at the same time as the wolf, and both of them came out quite nice. No air holes or defects in the surface, and they caught all the detail. The Rebound 25 makes much less mess than the urethane molds I made last summer, which is something that matters when you’re doing it in your kitchen.

The molds are not cheap, unfortunately. I estimate that the wolf and the cougar molds, including the mother molds, the silicone and the SuperSeal, cost about $15 each. They’re about 9 inches wide. Of course the water-based clay was sealed so it can’t be used again, and the oil-based clay I used to create the edges of the molds now has bits of plaster in it. I suppose these materials should also be added into the cost.

I’ll now see if the new paper mache clay mixture will work in the molds. If I get a good result I’ll let you see them (and maybe the hippo that is still waiting for her mold), but it probably won’t be until after the New Year. Until then, I hope you have a fantastic holiday, and that you’ve thought up some fun and interesting new paper mache projects to show us!

50 thoughts on “Making Silicone Molds – for Paper Mache Experiment”

  1. Hello Jonni

    What a useful resource you web site is, and you and your readers are very creative. I would like to do some paper mache, and have a particular project in mind. Problem is being such a newbie to PM I have many questions. If you do not mind i will take the liberty of asking them here.

    I have seen some animal sculptures made from PM by a French artist Marie-Astrid Montaignier

    her website is here

    as you can see from the site and the image I have uploaded these sculptures are lamps.

    My questions are : How and with what would you build the armature, I am thinking thin wire, what are your thoughts? Should the wire be “dressed” with paper to allow the outer skin to adhere better and to give better support? Again I would appreciate your thoughts. Finally what paper should I use, and what glue to get a finish that allows light to pass through and yet be strong enough for everyday use ? Do you have any tutorials on how to make the armatures – skeletons or could you point me in the right direction of one?

    Thank you if you have got this far. I look forward to hearing your expert opinion.

    Many Thanks


    • Hi Andrew. I’ve never done anything like this, but it looks like she’s using a wire armature that is probably shaped by hand, without any internal pattern or supports. I don’t know how she’s getting the legs and heads attached to the bodies – I think you would just have to get yourself some lightweight wire, chicken wire, perhaps, and do a lot of experiments. You wouldn’t be able to use very many layers of paper mache over the wire, because you need the light to shine through.

      In other words, I don’t have any advice for you, but if you figure it out I sure hope you’ll let us know how you do it. These are really lovely lamps.

  2. Hi Jonni I am making a mask and I am using a Styrofoam head as my armature I am going to paper mache it first then cut it off the Styrofoam head. I am then going to use the paper mache clay then after that dries I am going to use silicone rubber to make my mask. I am making this to put over my PVC mannequins for my outdoor Christmas scene. My ? is will my mask be flexible and will it be alright in the heat and cold outdoors? Thanks

    • Hi Sharon. It sounds like the final mask will be made out of silicone rubber. Is that what you meant? Or will you be making a rubber mold, and using paper mache to create a copy with the mold? I don’t know how silicone holds up to the weather, (it is definitely flexible), but my experience with paper mache tells me that it isn’t a good material for outdoor displays. Some people have good luck with marine varnish over paper mache, but it hasn’t worked for me.

      • hey jonni yes that is correct the final mask is going to be silicone mask. thanks for your comments I might try something different.
        last year for Christmas I made a big igloo out of rabbit wire burlap and then the paper mache it lasted thru Christmas and even til February and we had a lot of rain and ice. I used a lot of shellac over my paper mache igloo I am going to try something different this year with the paper mache. So thanks for your comments they r much appreciated your work is awesome.

  3. I have read the posts on making silicon and other molds but I am still confused on the best method for my project. I am making a very large (12’x5’x2′) art project and it will be covered in paper mache masks. My question is what do you think the best method of making a mold that can be used in quantity. I probably need to make about 75 or so over the next several months and I am trying to find a cost effective way to do it. I could buy good quality masks at a party store but they are $8.95 a piece and I am thinking I should be able to make them cheaper. I will probably have between 2-3 types of masks.

    Sammamish, WA

    • Hi Shane. If your individual molds are just the size of the masks, you could try plaster molds. I haven’t used plaster molds with paper mache, but Adam Shaw wrote a nice article for us, showing how he uses negative plaster molds with paper mache. If you scroll down below the information he provides about using the 3D program, you’ll see his technique for using the plaster molds. Since they don’t bend or stretch, your original designs can’t have any undercuts. And you’ll need to follow his instructions carefully to prevent the paper mache from sticking to the plaster. If you want more details on your masks after they come out of the mold, you can always add more to the face of the dried mask.

      I hope this helps. Be sure to let us see your project when it’s done!

  4. Hello and happy new year to you,
    I was wondering if you think, using the sealant you mentioned on average paper clay items will allow for said items to be used to create a cast?
    I have a set of antlers made from basic paper mache and sanded down ( this was before i found your awesome recipe sadly). I wanted to use a basic moulding and casting kit to create duplicates of them in a stronger material.
    However I am afraid that with them being paper mache, that they will be destroyed by the attempt or break down from it or something else bad.


    • This is a hard question, Nyura, and should probably be answered by someone who is an expert in making silicone molds. The problem won’t be the silicone – but you may have spotting issues with whatever sealant or release you use on the original model, if it’s at all porous. Has the paper mache been sealed with a good acrylic varnish? If so, that should prevent oil from seeping into the paper and causing discoloration.

      I just did a Google search and turned up a forum for mold makers that seems to be active. You might want to ask them about your concerns before you start. And be sure to let us know what you find out!

  5. Hi, Jonni,
    Thank you for all the good information and the kind way you reply to all. I have been using latex molds to cast paper sculpture and have found the paper sticking to the mold.
    So, I am now ready to try silicone and have chosen Rebound 25 because it is brushable. But my models are of plasticine, specifically Van Aken because it is sulfur free. My question is, based on your experience with Rebound 25, is the plasticine too soft a material to brush on silicone? In other words, how does the viscosity compare with latex? My sculpts are very detailed so I’m concerned with pot life. I think Rebound 25 is 25 minutes. By the time you mix it, it is even less. Your sculpts are around nine inches. How long did it take you to brush the first coat on?
    Thanks again for your generosity.
    ps I can relate to the garbage filled with rejects!

    • Hi Judith. The Rebound is thinner than the latex, in my experience. You shouldn’t have any trouble brushing it on without damaging your modeling clay. And although I didn’t time it, I recently made a new mold for my lion’s head, which is about 18″ long and 6″ high. I don’t know how long it took to brush on the first coat, but the Rebound was still workable when I was done.

      • Thank you! I’ve ordered the Rebound and the other products you recommend. You’ve been an enormous help.

          • Hi Judith. I can’t take just the picture out of your comment without removing the entire comment. I’ll delete it if you want me to, but I actually wish more people would post photos of themselves. We talk to each other all the time here on the blog, and it feels like we almost know each other – but I almost never get to see what my readers look like!

          • Yes. today’s the day. Smooth on suggested a test piece first. Without air conditioning in my studio, I have to wait til evening.
            I’m also trying to “save” my latex molds. With all the advice on mold releases out there for latex, feared most have been ruined. Castor oil and rubbing alcohol work according to an expert with 20 years experience.

  6. Some types of silicone mold materials (there are a few different chemistries) will not harden in the presence of chemicals that are in paints. I would definitely ask before using any silicone to prevent wasting that expensive material! Love your blog, Jonni! Thanks for all the tips.

  7. Hello,
    I have a question about undercuts when using a silicone mold. Does the silicon come out of the plaster mother mold or is it in there permenantly? If it’s permenant, doesn’t that defeat the purpose of a flexible mold? I guess I need to know more about unmolding the finished mask.

    • Hi Tyra. You would normally build up the outside of your silicone so there aren’t undercuts that would trap the mold inside the outside plaster shell. The best place to learn about silicone and urethane molds is on the Smooth-on website. Click on the video tab at the top of their page.

  8. Hello – love looking at all your beautiful paper mache art projects! I had a question about your molds – do you think you could make a mold from a finished project that has been painted already? would it ruin the paint job?

    • I don’t know. I have wondered that, myself, but I’ve always been too chicken to try it. The folks at sold me the silicone mold stuff, and they’re really good at answering questions that you send them by email. I’d suggest that you ask them before you try it. And please be sure to let us know what you find out!

  9. Hey Jonni – great work with the dog and cat – hope they don’t fight on the wall. But seriously, love these marvelous sculpts and subsequent molds. Curious to know – what specifically did you use to make:
    1) the original clay sculpt (which water based clay?) and

    2) what is the recipe for the clay for reproduction from the molds made?

    3) And finally, which mold material did you use?
    Lovely work that I’m sure a lot of time and careful consideration went into. Hope your holidays were great as mine. Looking forward to hearing from you. Yours, Joanne

    • The originals were made with water based clay, the mold was Smooth-On’s Rebound 25, a silicone material that comes in two parts. I tried many recipes for the clay and never found one I was happy with, because the paper bits seemed to catch in odd places and formed voids in the surface of the finished piece. I ended up using a home-made “instant paper mache” that I talked about here. The recipe is on that page. For some reason I decided that I didn’t like the wolf, so I never finished him. Now I can’t remember why I didn’t like him, so I might have to go back and do it again.

  10. This looks terrific. I’ve been experimenting with vinamold and I wonder if I could use it to do this process. Have you experimented with different smooth-on silicones or with vinamold?

  11. hey jonni, been learning tons from your site, have it on my bookmarks, and I’m completing a series of sculptures based on your methods learned here! what kind/brand of water-based clay did you use for your animals?

    • The sculptures on this post were first made with a locally-available sculptor’s clay from Georgie’s pottery supply store in Portland, Oregon. Then, of course, the molds were made from that, and the final pieces were made using the plaster-paper pulp recipe. Natural clay comes in a lot of different textures and “feel,” so you would just want to find one that you like working with.

  12. Hi Jonni,
    Thank you for the tip suggesting I use the plaster/paper recipe instead of the paper mache clay recipe to use inside a mould. I will give it a bash.
    Also, I have gone to our hardware stores here and am not able to obtain “joint compound” in a powder form. Here, it’s all pre-mixed which is not what I need to make your paper mache clay. Would anyone out there who lives in Australia be able to advise me what I could use instead. It was suggested I use cornice cement as it has a gluey feel to it, but also dries quickly.
    Any suggestions would be really appreciated.
    Thanks again Jonni for your suggestion and I will give that a go.
    Kim from Australia.
    (I noticed you had another Kim, so thought I would put down where I am from to differentiate between us).

    • Hi Kim from Australia. The paper mache clay recipe actually uses the pre-mixed joint compound. You can use the dry powder too, but you need to pre-mix it according to the package instructions before adding it to the rest of the recipe. So the product at your local hardware store should be just fine.

      I’m not familiar with the cement product, but you may find that it firms up too quickly. Also, since it must contain Portland cement rather than calcium carbonate (like the joint compound) it will have different characteristics when mixed with the glue. I don’t know if it would work, but if you experiment with it, let us know how it turns out.

  13. i’m so happy i JUST found this AWESOME site!!! i can’t wait to go through every little detail… thank you for your wonderful ideas!!

  14. Lovely work! I want to try the silicone.method I saw on YouTube to make a mold…have you tried that yet? If you’re interested I can find and send you the link-just email me. I love coming to your site and getting inspired!

    • Hi Kim. I did try using silicone caulk for a mold last year, but I wasn’t happy with the result. The caulk is not intended for this use, and therefore it doesn’t work as well as products made for molds. However, if you have a small item and you’d like to try it, you might be happy with it. I found it difficult to work with because it’s so thick, and I couldn’t find anything to spread it with that didn’t stick to the caulk – and I seem to remember voids forming under the caulk because it isn’t thin enough to brush out. Just my experiences with it. The video on YouTube seems to prove it can be done, though. If you try it, please let us know how it turns out.

  15. Merry Christmas Jonni! Those are amazing! The wolf is quite realistic, but are you going to make the lower jaw? Wolves are my most favorite animal! I’d love to see it when its done!

    • Thanks, Monica. The shape is based on traditional leather masks, which leave off the lower jaw. The shape will give me access to all parts of the inside of the mold – we’ll see how well it actually works on the wall when they’re all done. Wish me luck…

    • Thanks, Jessie. I’m playing around with human expressions on critters, having fun with it. I hope you’re having a great Christmas Eve –

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