Casting Silicone

[alanv73]

Having had my own mishap trying to use hardware store silicone caulk to make a PR mold, I was very interested/surprised to discover that Make Magazine's blog has posted a tutorial on using clear silicone caulk as a casting silicone. Apparently, the secret is cornstarch! And hardware store xylene can even make it pourable;

http://blog.makezine.com/archive/2010/10/how-to_make_cheap_castable_silicone.html

 

[Glass Scratcher]

Ok, I'll play.


Do you make a slurry with the cornstarch, and then ad it?

 

[alanv73]

According to the author, the cornstarch is mixed approx 1:1 with the silicone. I think the xylene was a separate discussion that can be used to make the silicone pourable. I recommend you take a look at the Instructable as may have distorted the procedure a bit.

 

[micharms]

I took a look at the instructable. It seems interesting. The addition of xylene was a comment by one of the other readers but didn't really have any more info on that aspect. Further along in the instructable the author talks about thinning the caulking with mineral spirits to make a paint but then also states that the tear strength decreases with this addition. I wonder what would happen in something thicker like a mould? I have mineral spirits and can easily get some caulking so I might just have to give this a try. Thanks for the link

Michael