Silicone Caulk Mold Tutorial

[cavx]

Great tutorial. Soap and water is way cheaper than acetone I will have to give this a go.

Just my $0.02 worth that someone here might find useful. I mixed (with some experimentation) the caulking silicone and acetone and found that 10 parts silicone to 1 part acetone is a good mix. You have to stir vigorously (or shake in a sealed glass jar), and after a few minutes, the acetone breaks the silicone down from the sticky paste into a pour-able sludge. As the acetone evaporates, it goes cold producing condensation which aids in the curing of the silicone. It also seems kill the adhesive properties of the caulking silicone and I found that the silicone just peeled off most surfaces I applied it to without a release agent. Having said that, it always pays to keep a jar of Vaseline on hand because if it sticks, it will stick like the glue it is and you may not get it off the part, so don't risk.

You can also soak strips of fabric in the silicone to add strength so a base silicone layer so it does not tear (if too thin) as it pulled up of the surface.

 

[Anzh]

Why not both?
I made this wax-grenade with a caulk silicone mold (actually not following this tutorial here, but just smearing the silicone onto the master). After I pulled some wax-copies, I tried some other materials, including caulk silicone and expanding foam. The foam copy came out without any kind of mold release, and, keeping in mind that the mold was only held together with some tape, was in pretty darn good shape (unfortunately, I demolded it too early, so the copy wasn't perfect).

The silicone copy on the other hand was more or less a proof of concept. As silicone wants to stick to silicone AND is not easy to paint, I tried to kill two birds with one stone and brushed some graphite powder into the mold to release it from the mold and prime it for further painting.

While priming and releasing worked out great, the copy itself didn't turn out that good, as my method wasn't the best. I just pushed the silicone into the mold using the...I actually have absolutely no idea how that thing is called in English, cartridge gun? You know, that thing you use to push the silicone out of the cartridge. This trapped some air in the mold (see first picture) and didn't get every single detail (second picture). But with some pratice, another type of mold and/or "brushing" the silicone into the mold using popsicle sticks or something like that, it should work just fine.

It should be noted though that the silicone seems to shrink over time; you can clearly see the silicone copy is smaller than both the wax- and the expanding foam copy.

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Oh, and btw, caulk silicone molds (at least the silicone I was using) can also handle higher temperatures, for a short time. I was able to pull some keyrings in such a mold, using molten pewter.

Thanks for this! I was wondering If this material would be good enough to sell and bring down costs, but with the shrinking over time, maybe it shouldn't be sold. I will definitely find some use for this though.

Thanks again, it was very helpful.

 

[Anzh]

About how long does this take to cure, btw?

 

[cavx]

About how long does this take to cure, btw?

Depends what it is mixed with and how thick the layer or wall is. When I was playing around with this, I found I had a 10min potlife and a solid by 60min.

 

[Anzh]

Depends what it is mixed with and how thick the layer or wall is. When I was playing around with this, I found I had a 10min potlife and a solid by 60min.

alright so it's not that bad. thanks!

 

[Anzh]

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[cavx]

alright so it's not that bad. thanks!

I was mixing the caulking silicone with acetone. The mix ratio was about 10 parts to 1. As the acetone evaporated, it went cold creating condensation which helped speed the cure time.

 

[Anzh]

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I was mixing the caulking silicone with acetone. The mix ratio was about 10 parts to 1. As the acetone evaporated, it went cold creating condensation which helped speed the cure time.

Did using the acetone cause any noticeable shrinkage?

 

[cavx]

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Did using the acetone cause any noticeable shrinkage?

Well in my case, none that I saw. I have heard soaking a silicone mold in Kerosene can change the size (expand?). In my case, the mix was for coating material in cheap, paint-able (to apply with a brush, not colour. I used black silicone pigment mixed into white silicone to get the right colour) rubber. $4 per 600ml + acetone Vs $70/L was well worth some experimentation on. The results has promise, just not quite the results I was hoping for, so when I hook back into that project, I will have to cough up for the $70 stuff.

 

[Kaykadem]

Does polyester resin on a silicon caulk mold melt it? i wonder it, because last time it was hard to replicate the original one, i did a pvc mold by vacuum forming but i was looking forward for this kind of 'cheap solution'