Making a silicone mold can be a very easy and rewarding project. This inexpensive and simple DIY project allows you to create a repeatable mold from very accessible materials. Some mold making materials can be very expensive or hard to find. Silicone and the mold-making ingredients are readily accessible to almost everyone, everywhere. In this video tutorial, you will learn how to make your own straight-pull silicone mold.
When choosing what to make a silicone mold of, there are a couple things to consider. For a straight pull mold like this one, be aware of things like overhangs and undercuts. Protrusions can make it difficult to demold concrete castings without damage or voids. The surface should be as defect free as possible, unless that is what you are specifically going for.
Silicone is very adhesive so use some kind of barrier between the item being molded and the silicone itself. Wax is painted onto the concrete item followed by a spray-on mold release agent. This will help the silicone mold decouple cleanly from the concrete item.
Mineral spirits are mixed with silicone to thin it out making it more runny (less viscous). This mix can be painted onto the surface to help pick up fine detail and ensure full silicone coverage. This technique is the first step for this mold-making project.
Silicone molds will have thinner and thicker spots depending on the item being molded. But silicone does not set when it is too thick. Corn starch mixed with silicone will make the silicone set at any thickness. It is also a thickening agent. A corn starch and silicone mixture is spread over the concrete item to in an even distribution to form the mold.

00:00 - Introduction
00:37 - Urethane molds and Silicone molds
02:48 - What type of silicone to use
03:37 - Beginning tips
04:59 - Mold release agents
06:07 - Wax barrier
07:15 - Technical steps and examples
07:49 - Applying release agent
08:11 - Avoid these for straight pull molds
09:13 - Making silicone mold
09:52 - Step 1 of 2 - silicone and mineral spirits
11:51 - Silicone slurry
13:11 - Step 2 of 2 - silicone and corn starch
13:26 - Silicone rubber paste
14:44 - Concrete base
17:02 - Mortar mix design
18:40 - Demolding process
21:58 - Silicone mold reveal
25:03 - First casting
30:30 - Demolding first cast
31:33 - First cast reveal
35:41 - How to repair a silicone mold
37:41 - Second test casting
39:56 - Second cast reveal
40:24 - Advantages of DIY silicone mold
41:05 - Colored casting
42:16 - Final reveal and conclusion
43:15 - More test samples

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