How to Make a Silicone Mold for Paper Mache

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Costume designers and Etsy sellers –

Do you may need multiple copies of your paper mache sculptures and masks?

It’s easy to make silicone molds for paper mache with Rebound 25.

In the video above I go through everything you need to do: getting your clay model ready for the mold, brushing on the silicone, and then creating your first copy with paper strips and Titebond II wood glue. And I include some suggestions for embellishing your finished paper mache product to make each copy unique.

I made this video especially for folks who need to make a lot of paper mache copies of a clay model, and they want to use products that are especially made for creating silicone molds.

There are videos online that show how to make cheaper molds using silicone caulking, but I’ve tried all those recipes and none of them come close to the quality you can get with the Rebound 25.

I buy the product in the larger size because I create clay models for all of the patterns I make for the masks and wall sculptures behind me in the video. The silicone will last for a very long time if you keep the lids on tight.

But if you only need one mold, they sell the product in smaller quantities, too. It isn’t cheap, but I never use anything else for my molds.

I have some screen shots below if you prefer to read the instructions instead of watching the video.

But first, here are the links of products you’ll need to make a brush-on silicone mold:

Items you might need to order:

Items available locally or online:

Helpful videos:

Screen shots from the video:

Prepare the clay model for the silicone mold

Remove any parts of your clay model that you don’t want to include in your mold. In this instance, I removed the fox’s ears. The clay would get trapped inside of the long thin shape, and it’s easier for me to just trace around the ears and make them out of cardboard.

You might need to make a two-part mold if you need to keep those areas, or if you wouldn’t be able to reach far enough inside of a larger mold. In that case, you would need to add the paper mache to each half of the mold, let it dry, and then put the pieces together with more strips of paper and glue.

Smooth the model surface

Remove any extra bumps or dips that will make it more difficult to add the paper mache inside the mold. Paper doesn’t bend as easily as clay, so the smoother your model is, the easier and faster it will be to create your paper mache casting.

Brush the model with water to smooth

Smooth the model even more by using a soft brush that’s dipped in water. If you’re using an oil-based clay instead of the wet WED clay that I’m using, follow the manufacturer’s recommendations for how to make the surface of your model smooth.

Put the model on plastic

Put the model on a table covered with plastic, and put more clay around the bottom, where it meets the table, and around any area where you don’t want the silicone. In this case, I didn’t want to make a mold of the back of the model, so I created a clay dam, which creates an edge for the mold.

pray the model with clear finish to seal it

Spray your wet clay model with clear finish. Any brand should work. I normally use the Krylon brand, but this time the Valspar brand was what I had down in the basement.

Do not spray your model if you used oil-based clay.

How to Make a Silicone Mold for Paper Mache

Put on your gloves and measure equal amounts of Part A and Part B of your Rebound 25 silicone. I use medicine cups for small quantities, but you can use a gram scale, if you have one.

Brush the Rebound 25 silicone over the clay model

Brush the Rebound 25 over your model.

Be sure to keep the layer thin so you can see any bubbles that form. Make sure to check the deeper areas, like the nostrils, the corners of the mouth, or any crack or crevice. Air can get trapped in those areas, and the silicone will cover the air and hide the bubbles.

If you don’t pop the bubbles, you’ll have a weird spot on the final mold.

Let the silicone cure until it’s tacky, not sticky. Don’t wait until it’s completely hard, or the next layer may not stick to it. It may take from 20 minutes to several hours, depending on the temperature in the room.

Add Thi-Vex to thicken the silicone mold material

Mix more of Part A and Part B for your second coat. I used clear drink cups to measure this time, because you can look at the two cups from the side and see if you have the same amount.

Mix the Part A and Part B first before thickening it with the Thi-Vex. You only need a few drops, so pour a little of the Thi-Vex into the cap first, and then into the mixed silicone. That way you won’t accidentally add too much.

Mix the Thi-Vex into the silicone. If it isn’t thick enough you can add a little bit more. You’re looking for a consistency that is thick enough so it doesn’t run, but it’s still soft enough to go into the deeper areas of the mold.

10 Use a popsicle stick to spread the thickened silicone

Use your popsicle stick to spread the thickened silicone over the mold. Make this layer as smooth as you can if you intend to use only two layers.

If you’ll be making many copies of your paper mache mask or sculpture, or if you’re selling your product and you need the mold to last for a very long time, you’ll want to use more layers than I did. Three or four should be plenty for any purpose.

Fill in any undercuts on the outside of the silicone mold

Fill in any undercuts with the thickened silicone. I didn’t mix up enough for my second layer to completely fill in those undercuts, so I let my second layer cure for about an hour, and then mixed up some more silicone.

You can’t leave undercuts, because you need to pull the mold out of the hard outer shell while the dried paper mache mask or sculpture is still inside.

Create the mother mold with plaster cloth

Make the mother mold, a hard outer shell, for the silicone mold. I use two layers of plaster cloth, because that’s strong enough for the molds I use.

If your molds will be used more often than ten or twenty times, or if you think the molds will be handled roughly for some reason, use more layers of plaster cloth, or make a stronger mold.

You can use wet plaster reinforced with burlap, or use an epoxy product. there’s a link above for a video that shows you how to use the epoxy – but it’s expensive. 

Mix Titebond II wood glue with water

Mix a small amount of water in with your wood glue to make it a little thinner. Don’t add too much, though.

If you want to try using a water and flour paste, make sure you test it first. On a larger mold the wet paper mache could warp or curl up as it dries. It might work, but test it to make sure.

Add a layer of paper strips and wood glue to inside of mold

Apply a layer of paper and glue to your mold. I’m using brown paper because it looks better in the video than newspaper that has writing all over it, but newspaper works just as well.

Use very small pieces in areas that have a lot of detail, and use larger areas that are smoother. In this case, I wasn’t able to get the brown paper to go over the nostrils properly, so I used one ply paper towels in that area.

Press paper tightly to surface of mold to get a good casting

Press the paper down tight against the mold. If you put a little wood glue on your fingers, the glue will help your fingers slide over the paper strips so you can get them to lay down flat and tight. If you press the paper down flat enough, you’ll have a perfectly smooth finish on the outside of the finished paper mache casting.

Put your paper mache over the entire mold, and then go back and add another layer.

Two layers are strong enough for my purposes, but most people will need a stronger mask or sculpture than I do. You will need to experiment to see how many layers you’ll need. More layers will obviously need more time to dry.

Let paper mache dry before removing from mold

Let the paper mache dry completely before you pull it out of the mold. You can ruin your casting if you try to take it off before the paper mache is dry.

You can tell that it’s ready to come out of the mold if it’s easy to pull it away from the silicone mold.

I put mine in front of a furnace vent that blew warm air over it, and it dried overnight. The shapes might warp if you try to speed up the drying time by putting the mold in the oven – be sure to test it first to make sure it will work.

Paper mache is now ready to be painted

Your paper mache casting is now ready to by painted. If you want each copy to be unique, you can make fur with tissue paper or paper mache clay, eyebrows with air dry clay, add a mane with raffia – there’s really no limit to the creative ways you can embellish your new paper mache mask or sculptures.

If you make paper mache copies using Rebound 25, we’d love to see how they come out. Be sure to visit the Daily Sculptors page and show them off.

Have fun!

8 thoughts on “How to Make a Silicone Mold for Paper Mache”

  1. Hi Jonni! Absolutely love your work and refer to your site often!
    I do make sculptures that always end up with more orders of the same. It does take a lot of my time to remake them. My question, is there a way to make a silicone mold that could conquer that? I did ceramics for many years and those were 2 part (or more) molds. Is it possible with silicone for paper mache?

    Reply
    • Hi Sheila. Yes, you can use paper mache in two-part molds. The problem is that you can’t usually get your hands inside a two or three part mold, so you have to keep the pieces apart, add the paper mache, wait for it to dry, and then remove the paper mache from the mold. Then you would put the pieces back together with more strips of paper and paste or glue. This is a good video of using the brush-on silicone to make a two-piece mold.

      I’ve tried this a few times, and it works – but you have to put the pieces back together right after you get them out of the mold. If they’re left out of the mold without putting them together, the pieces change their shapes just slightly, and getting them back together is a lot harder to do. good luck with it!

      Reply
  2. were do you get the plaster cloth
    I wake hevey plaster mother molds with strips of burlap but they are are thik and heavy
    Thanks Wally Imfeld

    Reply
    • Hi Walter. I have to order mine online, because there’s no hobby store near me. If you have a store that caters to people who build model train scenery, you can get it there. I get mine from amazon.com if I just need a little, or from the Brick in the Yard company if I need a case. (I’m currently out of plaster cloth so I’ll be ordering from them today.)

      Reply
  3. Hi! Thank you for all you do! I’ve been following you for years and have two books:)
    -I’ve been working on this process for a while (reproducing masks) and the only thing you might want to note is that if you use an oil-based clay it needs to be sulphur free or otherwise the silicone won’t cure. This is info that I’ve frequently come across but I haven’t tried it. I did buy some sulphur free oil-based clay but didn’t like working with it (I love the regular plastilina.) and so I stick with WED clay. I hope this helps!

    Reply
    • Good point, Anna. I’ll put that in the post. I haven’t actually seen any oil-based clay that doesn’t say “no sulfur” on the label, but I’m sure there’s still some out there. I appreciate the tip. BTW, did you intend to give us a link to a private site? I can change that URL if you want me to.

      Reply

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