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African Animals Pattern Set.
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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:
- 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).
- 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 200º F.
- Never paint and seal paper mache if there’s any moisture left inside.
- When it is totally dry, seal it so it can’t absorb moisture from the air.
- 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. 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.
This is a reader-supported site. When you buy through links on this site, I may earn an affiliate commission. Thanks for your support! :) African Animals Pattern Set.
Save $10 when you buy this three-pattern set. Use the patterns to create memorable gifts, or to bring a little bit of Africa to your own home
I constructed a cardboard/paper clay/papercrete outdoor sculpture- it is a 6’4” sitting howling wolf. It was well over 100 degrees for weeks this year and I was hopeful that my layers sometimes 3” thick ( of the flour glue sheet rock mud and toilet paper combo) was dry prior to adding more) my very outer shell is all those ingredients above plus a generous portion of Portland cement mixed well and spread on 2-3 1/2” thick in places- it’s been really hot as I said but that final layer with the cement had to dry slow per cement instructions-
Fingers and toes crossed for it not to expand from the inside and bust apart during our extreme freeze thaw cycles in Central Montana!
I would much prefer to have done this all with papercrete and in the thinnest layers as Joni speaks about- but I was doing this blind-
It’s late August – At least now that I’ve read this I won’t seal it until last opportunity in Sept so it has more time to dry
My question is this: might I want to drill many holes into the thick places to encourage continued deeper layer drying for several weeks?
Hi Kate. I have never used the Paper Mache Clay in such thick layers, so I don’t have an answer for you. I use the thin layers so it can dry fast enough to prevent the growth of mold. The cardboard armature may be helping to pull moisture from the inside of the material, if there’s a hole in the bottom. I don’t know if drilling holes would make any difference. If there’s any water left inside at all, you may eventually see a stain appear on the outside of your sculpture. Since you probably aren’t getting as much humidity as we are here, the heat may be enough to make sure the sculpture dries all the way through before you need to seal it. We’ll all keep our fingers crossed for you. 🙂
Thanks Jonni I’ll drill some low angle holes and check for moisture loss in late September by placing plastic or Durand wrap to catch any drips coming out – if all seems dry I’ll use that masonry sealant’ Thomsons ‘ then acrylic paint then spar varnish over top of all of that. Goodness me! This has been a many months project as it looked rather like a Rottweiler dog at one point – had to disassemble and begin anew – the shear weight of this project is formidable!
Great tip to explore — mold can easily ruin papier-mache projects if moisture lingers too long. To prevent it, make sure your papier-mache dries completely between layers, use a fan or dehumidifier in humid areas, and store finished pieces in a dry, well-ventilated space. Adding a bit of salt or glue to the paste can also slow mold growth. If mold does appear, gentle mold remediation—like wiping with vinegar or alcohol—can help save your artwork before it spreads.
What do you think would happen if part of t’he water was replà es Witsel white vine gra?
A lot of people add vinegar. I prefer to just make sure the paper mache dries fast enough to prevent mold from growing, but you can use vinegar if you want to.
Hi jonni,
I’m making a paper mache for my summer art project. I don’t have any glue so I was going to use the flour paste recipe. But after hearing about it moulding I have become hesitant on using it. Is there any tips or tricks to stopping mould growing on it?
Mould can’t grow without water, so the way I make sure my sculptures last for years is to get them dry as fast as possible, and then keep them dry. If there’s no moisture, there can’t be any mould.