Paper Mache Recipes, Tips, Techniques, and Experiments

How to Keep Mold From Ruining Your Paper Mache



Today’s video is about mold, and how you can keep it from ruining your paper mache sculpture.

Here’s the short version: It’s all about the water! Mold can’t grow without water, so the way you can keep mold out of your paper mache is to:

  1. Use the fewest layers of paper and paste or the thinnest layer of paper mache clay that you can get away with. I use no more than three or four layers of paper and paste, and sometimes use less. When I use paper mache clay, I spread 1/8″ or less with a knife over the armature. (You can add more paper mache clay after the first layer dries, because it isn’t very absorbent).
  2. Put your sculpture where it can dry quickly – in front of a fan, over a furnace heating vent, or outside in the shade on a warm day. You can dry it in an oven if you need to, at around 200ΒΊ F.
  3. Never paint and seal paper mache if there’s any moisture left inside.
  4. When it is totally dry, seal it so it can’t absorb moisture from the air.
  5. Display the sculpture (or store it for next Halloween) in a dry place, the same sort of place where you’d display or store an original watercolor painting.

I have a house full of paper mache sculptures, and none of them have ever developed mold. I don’t do anything special to protect them, except for following the rules shown above.Β  Folks who live in the tropics may have to take different measures, but for the rest of us, drying the piece quickly and keeping it dry will help it last for a very long time.



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93 Comments

  • What does mold look like? Is it yellow-brown? I think I may have ruined my 2-month long project, as I found a clump of nasty-yellow blobs in my clay batch after I had set it to the project, and I put the clay on fairly thick where I needed to build. I mixed bleach into anything I added after that to save my mixture, but after 12 hours is when I found the drier surface had yellowed anyway. I dabbed more bleach onto the yellowing parts, but I don’t know if it’s enough. If it dries, can I save the project? Or, should I take a saw to my project and redo the affected parts? What would you recommend?

    • If the pm clay was brand new, it shouldn’t start to grow mold in just 12 hours. But maybe you have an extra lively batch of spores in your area.

      If the clay was made ahead of time, it could have started to grow mold before you applied it to the sculpture. If that’s the case, it might be best to cut out that part and start it over. Can you use a craft knife or a rasp to remove it? And did the mold show up while it was still wet, or after it was dry for quite a long time? I try to never add more than 1/4″ at a time, to make sure it can dry all the way through before adding more.

      • Thank you for your response. The batch I had was roughly one week old and I knew the risk as it aged. The thickest added was roughly 1/3 – 1/2 inch, to clarify, but I think it was a false alarm, this despite the yellow creatures inside the batch. I must have added so much bleach to the newly-added parts when shaping the clay to the structure that they stained yellow as they dried, lol, and I mistook the bleach stain for the mold. It’s nearly completely dry and there’s no sign of any mold growth, at least on the surface. I’ll remain cautiously optimistic, though I’m unaware of how fast it spreads. I’ll have to make that call soon. For future reference, does adding bleach to drying parts soak through to kill mold, say, for thinner areas?

        • I hope your sculpture shows no more weird coloration – it sounds like you may have taken care of your problem. I’ll keep my fingers crossed for you. As for the bleach, it will kill any living thing it lands on. The question would be how deeply it can soak into the paper mache. As it evaporates the gases might penetrate even further, but I’m not a chemist so I’m just kind of making that up. πŸ˜‰

          I don’t know how big your sculpture is, but if you can put it in the oven no higher than 200Β° F and leave it in long enough for the entire sculpture to heat up, that would kill any currently living mold. There’s a risk that you could get some cracking, though. If you’re still really worried about it, it may be worth the risk. Don’t let it go above 200Β° though, or the smell of burning glue and paper will spread through your house.

  • Thanks for all your tips! You have a great site with tons of helpful information and videos, you are awesome for sharing all your knowledge with others who love the craft too! Keep up the great work!!

  • I have never done paper mache before. This year my 4 year old says to me “mamma I wanna be an optimus prime TRANSFORMING dinosaur” so I have constructed a robot dino head out of card board I saw your video on mold are there any tips or precautions I should take as I’m keeping the cardboard

    • Hi Crystal. The best thing you can do is keep it dry. Mold can’t grow without water. But paper can pick up water from the air. Will you be able to varnish the dino? Any good acrylic artist’s varnish will keep it dry if it’s kept inside.

      I would love to see how that transforming dinosaur turned out. What a challenging project! Do you have a photo you can share?

  • I am embarking on my first project and was going to use PM paste to do a first layer on my armature of cardboard and wondered if I should just use the PM clay period. Oh ,by the way I am doing Angel wings as a wall ornament. I made a paper pattern ,cut cardboard then 50 feathers to cover the cutout.

    • I usually use just the pm clay, but lots of people like putting down one or two layers of paper mache strips and paste first. It’s just a matter of personal choice. Your wall sculpture sounds wonderful, by the way. I’d really like to see it when it’s done.

      • Thanks Jonni. I love watching your videos.I started the PM Clay process today.Weather has been rainy here so was waiting for dry air but I have fans going.If I can figure out how to load the pictures of my project I will.Really excited.

  • hi Jonni I am making an indian elephant with papier mache pulp and homemade clay, the only problem is small flies around it whilst its drying can you tell me why this could please, joss

    • Hi Joss. Something in the pulp or clay is drawing the flies. Are you using one of the recipes from this site? If so, the flies might be drawn to the wet paper or flour in the recipe. I’ve never had that problem, but different areas have different bugs. You could try adding a few drops of oil of clove to your recipe to try to mask the smell. It might make the flies move on to something else. Other than that, I don’t have any suggestions for you, other than to use the thinnest possible layer of paper pulp or clay, and to dry the piece as fast as possible.

  • I live in Puerto Rico the capital of yeast mold an humidity. I am trying my hand in paper mache and I am looking for a good strong paper mache recipie that can help resist mold (besides allowing all layers to dry).. also what product do you recommend to seal the project?
    Signed PARADISE

    • Hi Johanna. You can add salt or oil of clove to any paper mache recipe to help reduce the mold problem. Because your climate is so warm and humid, you might want to use a sealer from the hardware store, instead of acrylic varnish from the art supply store. I like the water-based Minwax clear varnish, but any brand should work as well.

  • Hello Jonni! Thank you for inspiring me! I haven’t done paper Mache since grade school days (I’m an old 42 now). I wanted to do something special for my mom for Christmas. She LOVES snowmen & decorates in a western & primitave/vintage type of way. My 1st project.. He’s an old paper book stuffed & wrapped in masking tape snowman. Covered with one thick layer (1/4″ or so) of your PM clay recipe. Oh… And a cowboy hat… Ha! I have a few questions…

    1. He’s hard when you tap on him. But not ROCK hard per say. It’s been about 3 days. It seems your sculptures are pretty hard. How do you tell when they’re completely dry? Does he need more time maybe? Or did I mix the clay wrong? Or should I have done more layers? I thought one layer of the clay would have been strong enough & im running out of time before Christmas ?

    2. In one of my photos.. I’m holding a star. I wanted to do stars for his eyes bcuz I didn’t inherit the artist genes. I cut them out of a thin layer of, somewhat dry, PM clay. Will they stay on and be sturdy by using a glue & water paste between them and the dry snowman? I’m not sure which technique would be sturdiest and efficient to attach them.

    3. I plan on covering him in the gesso if he ever dries. Will this help his sturdiness? He just seems so frail.

    4. Personally, I love the windy willow limbs used for his arms. And they match moms decor perfectly. However, my mom is a flighty, busy bee, who doesn’t take time to pack things away the greatest. LOL so.. My fiancΓ© pointed out that his branches will probably be broke in time & how should she store it? Makes sense. I didn’t think about it. Any suggestions?

    5. Lastly, I have a spray can of clear acrylic matte coating. Should or can I use this when he’s done & painted to preserve him?

    Sorry for the many questions! Thank you for your inspiration.!

    • Hi Sarah. We didn’t get to see the photo. I sent you a link to the photo resizer in your other comment. As for the drying, at 1/4″ he should be rock hard when it’s fully dry. It will always dry first on the outside, and that slows down the drying of the inside. Put him in front of a fan or over a heating vent where moving air can help pull the moisture out of him. The gesso will make him smoother, but it won’t make him stronger. If you think it is dry all the way through but there’s still a little bit of give in a few places, you might have less pm clay on those spots.

      As for the arms, that’s a tough one. Any feature that sticks out will get bumped, but if it’s possible to replace a broken arm with a new branch, it should be OK.

      And your spray can of matte coating is a good idea – but don’t seal him until you’re absolutely sure he’s dry all the way through. You don’t want moisture trapped inside.

      Good luck!

  • Hi Jonni – I love your work and this site! Yesterday I used some modeling clay to sculpt part of my armature. This morning I realized it hadn’t hardened, read the package, and found I used the clay that never hardens. Will this cause my sculpture to rot? I don’t want to take it apart if I don’t have to, but will if I need to. Thoughts?

    • Hi Tracy. I made the mistake of leaving some unbaked Super Sculpey inside my appaloosa colt sculpture’s head, and in about six months the oil started to seep out and you could see the stain darkening the paint. Very disappointing. If you used a clay that never hardens, it probably contains oil, but check the package to make sure.

      It won’t rot, though, if the clay is oil based. However, if it’s water based, like pottery clay or WED clay, and it wasn’t dry all the way through before you added the paper mache and paint, then the moisture inside the clay will eventually migrate towards the paper, and that will wake up some fungi spores. Which you definitely don’t want.

      So, I guess I’m giving you bad news, but it would be a lot better to take the sculpture apart now and fix it so you can be confident that it will last, instead of hoping it won’t matter, and finding out six months later that it really did matter, a lot. Sorry. πŸ™

  • hiya, jonni!

    i’m hoping to create large, protruding masks using mostly paper mache and pm clay over an armature, but i’m a little concerned – these would be worn for hours at a time and additional cloth encompassing the head of the wearer would trap heat and moisture in, creating a miniature sauna inside! with the nature of the other pieces of the costumes i’d hope to make these for, i would honestly expect the temperature inside the masks to reach around 120 degrees F or so.

    if i use varnish to seal the pieces both internally and externally, would there be any concern that these conditions might make the varnish dangerous to the wearer? do you think the varnish may have to be reapplied over time? i really don’t know much about using sealants, the only paper mache pieces i’ve made have stayed planted securely indoors and don’t get to go on any fieldtrips. is there a material or brand you would recommend for the sort of project i’m picturing?

    either way, thanks a ton and take care! <3

    • Hi Mo. I have been told that for long-wearing masks, the acrylic varnish you get at the art store will eventually soften if worn directly against the skin. Since you expect the masks to be so uncomfortably warm to wear, I would suggest making them extra big and use strips of foam on the inside to allow for air circulation inside the mask. Also, if you could leave holes somewhere at the top of the mask so hot air could get out, that would be really helpful too – both for the mask and for the person wearing it.

      They do make materials for sealing wooden bowls that are food-safe. You might want to consider using one of them on the inside of your masks, if they’ll be worn for such a long time. The conditions you describe sound very uncomfortable, if not actually unhealthy, so anything you can do to make the costume lighter and cooler would be a good idea. And you might want to contact someone who makes theater costumes, for some more advice. Kevin Doheny might have some ideas for you, or your local theater group.

  • Hi Jonni,

    I have been watching so many of your tutorials and your site is truly an incredible resource. I appreciate any advice you might be able to give.
    I am working on my first paper mache sculpture and I have a few questions. You mentioned doing only a few layers (3 or 4) of paper mache and then drying it quickly. My first question is, if I do the same number of layers (3 or 4), should I just add them back to back, since as you pointed out, subsequent layers will simply re-wet the previous layers? I wanted to add the paper mache clay to the surface of the sculpture but I assume that would also “re-wet” prior layers. Should I do this while the prior layers are still damp or tacky? I am attaching a pic of the sculpture in hopes you will have idea of the issues. One is, the size, and weight. I did create a form/armature, but areas of the form were VERY light on paper the current sculpture is being held up by a central copper pipe at the moment but I was planning on removing it. I am wondering if the layers of paper would be strong enough to support the weight or per

    • Sorry, I did not finish my question.

      But you can see one question is in reference to physical support of the structure. (I maybe started too big for a first project.)

      Another question is, if I leave the bottom of the form/sculpture open (not completely enclosed in paper mache), would that be bad? I assume if I sealed the exterior/surface once completed, the interior would still be open to moisture and the possibility of mold?
      And how many days would say could I be pretty certain it the sculpture is totally dry (the outside feels pretty dry right now and it has not even been 24 hours since the last application).
      I have it in front of a fan and I am wondering if I should leave it for a full week?

      Sorry for disjointed questions and thanks in advance for any thoughts/suggestions.

      Amon

      • Hi Amon. We can’t see your armature, because the photo didn’t come through. I hope you’ll try again – this usually happens if the file size is too big. The system needs the file to be under 250KB. It is best to seal the inside if the paper mache is open to the air. Would it be possible to use a can of spray varnish to hit most of the inside of the piece? Or if you have to cut it apart to get the armature out, it might be sealed at that time, before it’s put back together?

        I don’t usually put on layers of paper and paste before adding the pm clay, but I know a lot of people do like doing it that way. I would let the paper mache dry as well as possible before adding the pm clay, so you have a nice solid base to work on. Then use a very thin layer of clay so it will dry out quickly. The moisture in the clay may dampen the paper mache underneath, but it should dry along with the clay. Keeping it in front of a fan to dry is an excellent idea. If you’re taking the armature out of the sculpture, the inside will have access to the air, so any residual moisture will evaporate quickly.

        I hope this helps. If you still have trouble uploading the photo even after making the file size smaller, please let me know and we’ll try to figure out what’s causing the problem.

        • Thank you for the quick response. Here is an image of my rough sculpt. She is about 4.5 feet tall (without her head, which I am sculpting separately.)

          I am pretty sure I already made a few major errors. I am worried that my first layer of paper mache (I used a recipe of flour, liquid starch, white glue and water) might somehow be prevented from fully drying, as the subsequent layer I simply used watered down wood glue. (I had a gallon on hand and wanted to use it up.) But watching your video has me worried that, due to the size of this, and the primitive way I constructed it, it won’t have a way to completely dry internally.

          • It’s beautiful, Amon. I do hope the paper mache will dry – the wood glue might harden on top of it, but it should (hopefully) all dry together. We’ll keep our fingers crossed for you.

  • just a comment regarding the mould growing in papier mache…..we live in a fairly damp area and get a lot of mould growing and always use oil of cloves to clean it up….it usually stops the mould reoccuring so wondering if you could add this to the paste mixture….you dont need much…we only use 4 drops of oil of cloves to half a bucket of water…. πŸ™‚

    • Yes, Janine – several people have told me that they add clove oil to the recipe, and it helps prevent mold. I don’t live in a place where I can personally test it, but others do say it works.

      I like that idea for washing off mold using clove oil in water – I could have used that in the last house I lived in, because the bathroom fan didn’t work, and mildew grew on the ceiling. I wonder if it would also work for paper mache items that already have mold or mildew – do you think it would help people save their work?

      • you could probably try using a mix of clove oil in the water with a mildly damp cloth to gently wipe off the mould….i think you would have to be careful not to use too much water, but i have scrubbed brick painted walls with the stuff and it works a treat πŸ™‚

  • Hi there,

    I do live in the tropics and have problems with mold! I was wondering if you have any additional ideas about how to prevent my paper mache projects from molding? I suppose my problems with mold reach far beyond paper mache, but in my experience so far my paper mache projects start to mold so quickly! Any help or ideas would be appreciated. I use a very basic recipe of flour and water.

    Thank you,

    Maureen

    • Hi Maureen. You might try a paste made with methyl cellulose (Elmer’s Art Paste) or use acrylic modeling gel for the paste. Or you could try the one on this page – I’m going to give it a try today, but I won’t be able to test it for mold. The vinegar should help, though. Try to dry your paper mache really fast, before the mold spores wake up, and then seal the dry paper mache so moisture from the air can’t dampen the paper.

  • Jonni,
    I am starting a huge paper mache and paper clay project and would love to get some advice. It is going to be a tree play house for the kids in out upstairs hall way about 6 ft wide at the wides point and max 8 ft high. I was planning on using 2×4 boards to make supports and chicken wire to make the shell then paper mache to cover it and paper clay to add the tree bark texture to the outside and a smooth texture inside.
    What recipe is the best to use for the paper mache and that will be strong enough to deal with the kids playing ( I don’t want them to have to worry if they bump the wall that it will get destroyed) ?
    I plan on hooking a small heater up inside it to help it dry since it is going to be so big.
    Should I layer it more due to what it is being used for ?
    I was planning on painting it too should I use Gesso to seal it before painting it?
    Any pointers are greatly appreciated!
    Thank you so much,
    Amanda

    • Hi Amanda. I have never made anything like this. I have a concern about the idea: I have never done any tests at all on either paper mache or the paper mache clay recipe for flammability, so you’ll want to do some of your own tests before you get too far into the project. Build something small with exactly the same materials – wood, paper mache, pm clay, etc., and see if you can light it on fire.

      I don’t usually worry about this issue because most paper mache projects are quite small, and they aren’t built like a small hut, like your project will be.

      The paste recipe doesn’t matter much – as long as it sticks paper together, it will work. I recently found this recipe on YouTube, which was recommended by a well-known puppet-maker, and it’s supposed to dry more quickly than most paste recipes. I haven’t had time to try it yet, but it looks promising. Acrylic gesso will help to seal the project, but you’ll also want to varnish the inside and outside after it’s painted, to keep humidity in the air from working its way into the paper mache.

      I don’t want to be a spoil-sport, but I think you can tell from my first paragraphs that I’m a little concerned about this project. Be sure to do your tests. And please share what you learn from your experiments, so we can all learn from them.

      • I started looking up how flammable the paper mache and clay is this sites says its not flammable ( in my option almost anything will burn if you let the flams sit on it long enoughand get hot enough , even bones burn ) http://www.craftandartisans.com/paper-and-papier-mache
        This one says it is flammable http://www.cockeyed.com/lessons/papermache/papermache01.shtml

        In all logic I would say that it is flammable considering it is made of paper and paper pulp. As far as the tree play house it is going to be indoors as well as never have a real fire in it the heater I was going to use is a very small one we had used in the babies room over the winter and I planed on setting a fan up to help keep the air flowing so it wont be just warm air blowing around. But most varnishes and shellac is flammable as well so that would add to it be flammable. The lights we are going to use in it are the discs you touch to turn on like the ones you can stick to the walls in closets and under kitchen cabinets that take batteries. Thank you so much for the pointers and advice I will keep you posted on the project and take pictures as it comes along!
        Amanda

  • Jonni, I’ve been admiring your site for years, and this summer tried my hand at paper mache viking helmets for the Dwarves at a Middle Earth Summer Camp we run at my school. Several of the little ones put on their layers too thick, resulting in a fine crop of grey fuzz inside their helmets. Is there any way to save them? Maybe if I wipe them down with vinegar? I’m squeamish about trying to dry them in the oven at this point, but would if you suggest.

    Many, many thanks for the wisdom of your website!

    • Hi Emily. That sounds like a really fun project, even if there has been a snag or two. How soon do the helmets need to be dry and ready to paint? If you have time, I think that leaving them out in direct sunlight would kill any mold and dry them quickly. Wiping them with vinegar first would probably be a good idea, too (and it would take away any musty smell). If the sun isn’t shining, do the vinegar thing and then put them directly in front of a fan – the more forceful the better. We need to get all the water out of the paper quickly so they can’t grow another crop of the fuzzies. Both the sun and a fan will probably dry them more quickly than an oven will.

      Good luck! And if the kids don’t mind, be sure to post a photo of some of the helmets so we can see how they turned out.

  • Hi Jonni.

    First, I want to express my gratitude for your kindness.
    The way you share your professional wisdom, will save me a lot of trouble.
    The potential risk of the mold was a very good point to mention.
    Following the same path of thinking, it just crossed my mind; if an antiseptic and quick drying is the answer, what if we can improve the evaporation properties of water by mixing it with an alcohol? That will increase the fluid evaporation and help with the bacteria/fungi, in a way.

    To explain where the idea came from; this method was used widely when I was child.
    It was used on little children to decrees their body extremely high temperature; the mix of water and an alcohol (min. 40%), in proportion 1:1, was applied on the skin over child’s whole body, then quickly was cooled with a few minutes long manually created good airflow. Usually, the temperature dropped straight-away by about 3-5 degrees.
    The quick evaporation from the skin was the ‘secret’. Alternatively, the vinegar was used as well, (but with the less success).

    Although, thinking about how to protect those first layers from getting too wet again; if the article is hollow with the hole on the bottom, the drying can be controlled from out- and inside. Or the hole can be small, and some kind of ‘heater’ can be inserted to help the drying inside…

    It would be interesting to know what do you think.
    Warm regards

    • Hi Inna. The idea of adding alcohol to the paste is interesting – I wonder if it would affect the stickiness? And would it be a fire hazard? If you try it, please let us know how it turns out.

      • Hi Jonni.
        I was thinking about the chemical compatibility with other chemicals myself. Nevertheless, bringing up the evaporation, I was talking about the not-flavoured drinking spirits, (such as; whiskey, vodka, rum, – any 40-45% that have been used decades ago). The adding water was for two reasons; to slow down the evaporation, and prevent the child gentle skin from rush. The main point to say; it can not be chemically too strong to influence the recipe balance. (Of course, there are other spirits are available nowadays, – more options to try).

        In regards to flammability; mix with water does not have an alcohol substance enough to burn. Although, think about the rum and cognac – their burn, but in some delightful recipes they safely go into the oven!

        I found your blog when I was looking to update my skills and knowledge. I am planning to start paper-mache, clay-and-cloth art doll making, and love the idea of making clays myself. Now, I want to play with this new idea. I only wish that my ideas were not running a bit too ahead.
        Maybe by the time you get settle in your new home, I’ll be able to share my ‘disaster’. πŸ™‚

        If I’ve got your news right and you did move into your new house, I wish you joyful life and endless happy moments!

        Thank you, again, Jonni.

        • Hi Inna. Yes, I did move, to a beautiful “little town by the lake.” That’s what the folks here call it – Hendricks, MN. I’m still trying to get organized, and although I have all my art supplies on shelves, I didn’t put them in any sort of order and I’m having a hard time finding things. The same thing is true with my bookshelves and my tools out in the garage – just a jumble! But I have started a new project (a fish, with colors that will look really nice in my new house).

          I’m really looking forward to what you discover with your experiments with the alcohol. If it works it will be a good excuse for me to bring home a bottle of vodka. πŸ˜‰

          • Hi Jonni.
            That is soo-o cool!!! (not sure over which part I am getting most excited. lol). But reading your words, I am getting all sort of pics in my imagination… well, apart from your fish! (I wish, I can see your idea).

            You made me laugh, – a bottle of vodka, ha?! Now you made it official. And if I succeed, you better supply the big one! πŸ™‚

            Can not resist to say; you are GOOD! You can not find your tools but already creating.
            I am very happy for you. Maybe one day, you’ll bother to take some pictures of your lake, new house… and your fish. πŸ™‚

            It is very nice to chat to/with you, (I am in the UK) πŸ™‚
            Hopefully, I have reason to chat with you again soon.

            Warm regard

  • Hello, How can i make paper mache with newspaper instead of toilet paper? My paper sculptures are just strips of paper with tape and finished a coating of PVA glue.

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