Make Your Own Silicone Molds

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Posted in WorkshopMolds-and-casting

Introduction: Make Your Own Silicone Molds

About: Hi everyone! I'm a hardcore DIY'er, I've published 11 DIY books, just produced my own TV show called Make Your Mark for PBS/APT, I make YouTube videos every week and I'm buried under a mountain of craft sup...

Using simple supplies, you can make your own silicone molding putty.

Step 1: Watch the Short Video Tutorial Here!

Step 2: You'll Need

Cornstarch

100% Silicone

Baby oil

Americana Acrylic Paints

Mixing bowl

Objects to cast

2-part plastic or air dry clay

Step 3: Make the Putty

Squeeze out enough silicone to cover your object

Add in about 1/2 the amount of cornstarch

Add a small dab of Americana Acrylic Paint

Add in several drops of baby oil

Mix thoroughly with a small spoon or stick

*Cover your hands in cornstarch and knead

Step 4: Make a Mold

Roll the putty into a ball

Press in your item making sure it covers all the details

Let cure for about 20 minutes

Remove the object

Fill with 2 part plastics, Sculpey or air dry clay

Step 5: A Few Items I Made

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    92 Comments

    I want to make silicone molds to make fondant forms for decorating cakes. Do you have a recipes for food products?

    2 replies

    For food products you really need platinum silicone putty - its the only one that's food and skin safe.
    Other silicones release strong acetic acid, or use tin - and these are no good.

    This sort of thing:
    https://m.youtube.com/watch?v=oxeRKWDWT0c

    If it's for something that's a one-off, you could use something called alginate. It's very cheap, but only good for one go really - used to make body casts and dental casts. Check its not minty before buying.

    Good Morning, Mark!

    I am currently attempting to make a synthetic skin for an animatronic stingray. The cast needs to be flexible to allow for wing movement.

    I was thinking about using silicone molding and urethane/latex casting. I know that in your video you state that plastics are best to use with the silicone mold. Do you think that I would be able to produce a functional, flexible cast using the silicone mold?

    1 reply

    It sounds like you can. The good thing is that it's not very expensive to make these molds so you're not out a ton of money either way. Good luck and let me know how it goes.

    Super cool! Does the acrylic paint serve any specific purpose or is it just to add some color? Love this instruct able! :-)

    7 replies

    I like it because I can easily see the details in the mold when I pour. When it's white sometimes you can't see the bubbles.

    I maintain that the acrylic paint has a chemical purpose. Silicone needs moisture to cure, which, ordinarily, must diffuse in from the outside. So, ordinarily, silicone caulk is useless for molding, as the sections are too thick to cure the interior. The acrylic paint contains water, which you are mixing throughout to enable cure.

    You are correct about the paint serving a purpose... You can swap out the paint for Glycerin. You can find Glycerin at Walmart or any pharmacy. Its a clear plastic squeeze bottle.... Just a couple drops of it will cure silicone without a doubt. Just dont add to much as it will cure faster the more you add... a couple drops to 1/4 cup of silicone is what i use. Also if you want the color still you can just add a couple drops of food coloring along with your Glycerin.

    Hi, just wondering if the mould ends up
    rigid or flexible

    I've had some for a couple of months and they're still flexible.

    Can I use olive oil instead of baby oil

    would this type of mould be okay to use for making plaster casts?

    2 replies

    Can you put this mold in the oven?