Silicone Caulk Mold Tutorial

Kwally89

Well-Known Member
Here is the mini-tutorial that everyone has been asking for!

MOLDING WITH SILICONE CAULK

Ok, so you are poor and want to make a quick mold of your sculpt/prop. What do you do? You use silicone caulk. Yes the same stuff that you use in the bathroom around sinks and showers.

Some people will tell you to mix in some glycerin or paint. Others say that you need to put some plaster in it. My method is A LOT easier and works just as well if not better. Ok, silicone caulk cures with water. When you squirt it out of the tube, it instantly begins reacting with the moisture in the air to become solid when cured. People have used plaster mixes to speed this process up because the silicone caulk produces acetic acid while curing. Acetic acid mixed with the mild base (usually a carbonate) in certain kinds of plaster produces water and a salt. This is obvious to anyone who has taken a general chemistry course...like I already stated, this is true, but is only need if you are casting something with the silicone caulk. In a simple mold, it is unnecessary.

MATERIALS

100% Silicone Caulk: I prefer the use GE Silicone 1 TRANSPARENT. I usually get two tubes, but it will differ depending on the size of your piece. In this tutorial, I used white silicone because they were in the transparent bin at Wal-Mart so I thought I bought transparent!
IMG_0258.jpg


A medium to large bucket

Some dish soap

a fairly sharp knife

silicone/grout dispensing gun

Procedure

First, you need to take your trusty bucket and fill it with luke warm water. As the water is coming out of the faucet, squirt about...idk...the volume of a golf ball or more dish soap into the stream. This just makes the dish soap mix and gets the suds going.
IMG_0257.jpg


Next, place the bucket next to your sculpt. Cut the ends of the silicone tubes off.
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It is beneficial to do this because it is hard to get a smooth surface if you squeeze all the silicone out in little snakes.

Squeeze ALL the silicone into the bucket. Stick your hands in the water and get them soapy and wet before working the silicone. The soap acts as a nice release from your sculpt and your hands. The only problem is the silicone has a hard time sticking to itself. Hence, my suggestion to cut off the ends so you don't have a bunch of little silicone snakes.

Work the silicone A BIT under the water. You don't need to play with it though it is fun. Grab the big glob out of the water and get it into a ball or pancake shape. Make sure the surface of the silicone is fairly flat. You don't want to capture any air bubbles.

Push the silicone over the sculpture making sure that you work it into the undercuts and detail areas.
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If I had looked closer at Wal-Mart, I would have used transparent. You really need to use transparent so you can accurately judge the thickness of the mold. Generally, a thickness of 1/4" will work just fine. I actually don't even make mother molds when the silicone is thick enough because it will hold its shape. With that being said, that means that the silicone doesn't have the ability to stretch very much before it rips.

You should be able to demold anywhere from 24-48 hours though it will dispel the acidic gas for 1-2 weeks. I usually get really excited and demold in 24 hours. If you got enough water in there and it isn't too thick, you should be just fine.

Any questions....feel free to ask!!!

HAVE FUN!!!

Kody
 
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My pleasure!

If anyone tries my method, I would love to hear what went well and what didn't. Also...POST SOME PICS!!

Kody
 
Neat tutorial, I might try that!

But I gotta ask, what's that it says there in bold lettering on the tube that you bought? I think it says "White." Might give those idiot Walmart employees a little slack...?

Looking forward to seeing the finished mold and casting.

Marcus
 
Neat tutorial, I might try that!

But I gotta ask, what's that it says there in bold lettering on the tube that you bought? I think it says "White." Might give those idiot Walmart employees a little slack...?

Looking forward to seeing the finished mold and casting.

Marcus

Let me guess? You or someone you know works at walmart :lol? I was just joking about it anyway.

What I meant was they filled the bin marked "transparent" silicone with tubes of white. The tubes look exactly the same so I figured it was clear. No need to get worked up about it :).

Kody
 
Very interesting tutorial looking forward to seeing more.

I learned long ago to always check when buying something at a big box store nothing ever gets put away in the right place. especially when they are the same package just different colors/sizes. (I think its more to do with customers than employees)
 
Very interesting tutorial looking forward to seeing more.

I learned long ago to always check when buying something at a big box store nothing ever gets put away in the right place. especially when they are the same package just different colors/sizes. (I think its more to do with customers than employees)

Very true! I was just poking fun :).

Kody
 
Great stuff. I've got a couple of uses I can put this method to. This will be much better than my usual cheaparse plaster one-off moulds, and very little more expensive. Thanks!
 
Great stuff. I've got a couple of uses I can put this method to. This will be much better than my usual cheaparse plaster one-off moulds, and very little more expensive. Thanks!

I hate making plaster molds especially when I am molding a vertical surface. It is just too much of a hassle. With the caulk, I can mold the vertical surface without a mold release and pick up a lot of nice detail....if you do it right! :lol

Kody
 
Yeah, absolutely - I'm OK at it, but it's not enjoyable. I've experimented with caulk in the past, typically when I had some leftover renovation stuff that was going off anyway. Never came across the water/moisture tricks though, those would undoubtedly have helped! And proper thixotropic silicone is just way too pricey to use on anything other than detailed scale models as far as I'm concerned; my pockets aren't deep enough to use it on 1:1 sculpts. So this is great. My stormie and my Kosh will both benefit. Thanks again!
 
Yeah, absolutely - I'm OK at it, but it's not enjoyable. I've experimented with caulk in the past, typically when I had some leftover renovation stuff that was going off anyway. Never came across the water/moisture tricks though, those would undoubtedly have helped! And proper thixotropic silicone is just way too pricey to use on anything other than detailed scale models as far as I'm concerned; my pockets aren't deep enough to use it on 1:1 sculpts. So this is great. My stormie and my Kosh will both benefit. Thanks again!

If you don't use the soap and moisture trick, it wont just not cure right, but it will be VERY VERY messy. This stuff will glob and stick to EVERYTHING if you don't get your hands and the silicone nice and wet in soapy water. After it is wet and soapy, it is very easy to work with. This whole process cost me about $10 :cool.

Kody
 
If you don't use the soap and moisture trick, it wont just not cure right, but it will be VERY VERY messy. This stuff will glob and stick to EVERYTHING if you don't get your hands and the silicone nice and wet in soapy water.

Yeah, I sure discovered that!!!! :)
 
Sticking with the frugal builder theme, I decided to make the mother mold out of expanding foam.

DOW's Great Stuff really is great stuff! Pun intended...wow lame!
foam.jpg


Obviously, it wont get a nice forming mother mold, but I just needed to hold the curve of the Nihilus mask. You can try to spread it on, but it is difficult so try to spray it nicely. You can also mist it with water to speed the curing and make it expand less.

foam2.jpg


Demolded
mold.jpg


I slush cast a prototype with smooth cast roto....that I opened 13 months ago!! Needless to say, it is very old and should look crappy. I have found that this stuff will work for A LONG TIME. Since I spend $10 on molding supplies, I wasn't going to use my good smooth cast! That would be fiscally irresponsible! For using silicone caulk, expanding foam, and 13 month old urethane, it looks pretty nice! Just dremeled the eyes out quick and lightly sanded.
sandedmask.jpg


ENJOY!
 
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