# Brush on silicone mold



## scourge (Jan 5, 2008)

I have a quick couple of molds to make for a customer. This how-to will show the lay-up, mold making and the finished resin cast. Here is one of the horns we have to mold:








First we have to block the inside with some clay:








Now we need to decide how to arrange the horn so we can start blocking in the clay. Since I want the mold to just be a 2-part mold, this seems to be the most simple position:








Now that the lay-up has been decided, we need to build our dividing matrix.
















Continue to build up your clay (matrix) around the horn. We need a sturdy platform all of the way around. This step is very important so it's wise to take your time.

Next will be finishing the matrix, making a pour spout for our resin and keying the matrix for our silicone and mother mold.


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## Terra (Sep 23, 2007)

Looking forward to this!


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## xrockonx911 (Jul 28, 2010)

definitely tuning in also!


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## Raven's Hollow Cemetery (Jul 3, 2011)

Three, and the number of the count is three. Ha-Ha-Ha! Staying tuned in for this one! Thanks!


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## annamarykahn (Oct 4, 2009)

4 & counting. ha-ha-ha!

lol

amk


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## scourge (Jan 5, 2008)

Ok, got some more work done tonight. Sorry, I got stuck at Crypticon. Will load pix tomorrow. I have to finish it by tuesday morning!


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## scourge (Jan 5, 2008)

Wow, I got really busy! Sorry! OK. So now we need to finish flaring out the walls of clay all the way around so we have room for both silicone and the mother mold. Also, we need a place to pour the resin when the mold is ready. I have taken a glue stick and wrapped duct tape around it until it was wide enough to pour in resin later. You can see the pour plug in the open end of the horn with our clay matrix halving it.
















Also, I have cut a long "key" all around the horn so the silicone mold can line up or register.


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## scourge (Jan 5, 2008)

Now its ready for silicone! I am using Smooth-On's Rebound 25 for this. It's a platinum silicone measured 1:1 by volume so it is pretty easy to use. Mixing equal parts A and B use a 1" chip brush to apply. Spread it thin to help avoid bubbles. It helps to "jab" the part to force the silicone into the nooks and crannies! After you get this most important layer on, hang out and pop the bubbles that appear (and they will). If you have an air compressor, you can lightly go over it to both help pop the bubbles and distribute the silicone. Make sure to brush the silicone at least 2 inches beyond the key we cut into the clay. This will be important.








When the first layer becomes tacky but does not come off on your finger if you poke it, we can brush on the next layer. You can put this second layer on much heavier. Brush all over to make sure all is covered.








I put on a 3rd coat after this before the next step.


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## scourge (Jan 5, 2008)

After the third coat is on we need to thicken our silicone. To do this we use ThiVex. Just a few drops is enough to thicken the silicone.








You can see how the thickened silicone hangs on the mixing stick without dripping off.








Now just trowel the thickened silicone over the horn making a nice smooth and thick coating. After the thickened silicone is tacky, I mix a small thin batch to brush over and smooth out the top of the mold.








Now let it fully cure over night.


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## Terra (Sep 23, 2007)

Veddy interesting. It's like watching a series with cliff-hangers


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## creeperguardian (Aug 22, 2011)

looks awsome


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## UnOrthodOx (Apr 24, 2007)

Hey, scourge, what clay are you using? 

With Klean Klay gone, I've been wandering around trying out different ones and haven't been happy yet.


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## scourge (Jan 5, 2008)

I am using Klean Klay. I stocked up before they went out of business. I might have 50 lbs. I feel your pain, it was the best for all my uses. The day I got the FAX that they were closing freaked me out! I have heard that someone else is making but it seems to be cracking with other not good issues. I am going to start getting use to Chavant NSP hard and Monster clay for future use. Until then, my Klean Klay supply is pretty good.


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## UnOrthodOx (Apr 24, 2007)

I hadn't seen any review of the Van Aken Klean Klay substitute yet, so am nervous to jump at it, especially as it's like 3x the price of good ole klean klay. 

I only had about 10 lbs and didn't get to hear about them closing out until it was too late, and have a bigger sculpt I was hoping to get done


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