Tuesday, August 12, 2008

Silicone Rubber Mold Making Tutorial

I am working on a nifty new project that requires me to create something I never have before-icicles.
After doing some research, I decided cast them out of a clear resin epoxy, such as Easy Cast, which was available at my local craft store (Michael's).
I dusted off my mold making knowledge from sculpture class in college and snapped a few pictures along the way so I could share it with you.
This method is for making casts of small items. Bigger objects would require a plaster "jacket" for support when casting!

-The item(s) you are planing to cast.
Silicone Caulk and caulk gun-available at your local hardware store, usually in or near the paint section. Make sure you purchase 100% silicone-not the white latex adhesives, they will not work.
A plastic bucket half filled with warm water
Liquid dish soap
Cooking Spray (Pam)
Saran wrap and masking tape (to protect work surface)
Vapor breath mask


Work in a well-ventilated area and wear a protective mask: the fumes of the silicone are very noxious. Cover a section of your work area with the saran wrap and edge with the masking tape. This is to keep the silicone from sticking to your table.
I made my icicles out of microcrystaline modeling wax, built on 14 gage wire. Make sure your item(s) are clean and dry, then spray a coat of cooking spray. This is a inexpensive but very effective mold release.

Using the Silicone
Pour some liquid dish soap into your bucket or bowl of warm water and swish the soap around to dilute it. You do not want tons of bubbles, you want to make the water feel super slippery.
Cut the tip off your caulk cartridge, puncture the inner seal and load it into the caulk gun according to the manufacturer's instructions. Squeeze a clump of the caulk into the bucket of soapy water. Using your vasaline-coated hands, reach into the bucket, scoop out the silicone and gently squeeze out the excess water.
Place the wad of silicone on your prepped item, smoothing into the cracks and crevices. Repeat until you have well covered your item(s). Check for any holes or gaps that need to be plugged. This will be a reusable mold, so I made made it about a quarter inch thick all over with a little extra on the bottom and sides for strength. I used about 2 1/2 cartridges of silicone for this little project.

The silicone will dry rapidly in the air. I usually let it cure for 24 hours, which also gives a chance for some of the fumes to dissipate. After it is well dried, remove your casted item and wash both with warm soapy water.


melroska said...

thanks for this tutorial (great pictures)! I'll have to try this out soon.

Craft Junkie said...

Awesome tutorial. I actually have all the items needed and an idea of what I want to cast. Thank you so much!

PurrPrints said...

Great tutorial--I'd love to see pics of how your icicles turn out from these molds too

Kathy said...

Wonderful information here. My artistic homeschooler would love to build something from these tools. Thanks for teaching me how!

S. A. Hart said...

Thanks for sharing this info in such a clear manner. Great tutorial

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