This Instructable will walk you through the process of creating a 2-part brush-on mold of an original.
2-part brush-on molds are ideal for replicating complex shapes that would otherwise be impossible with a pour (block) mold or glove mold. Using a brush-on technique gives the silicone more flex when demolding and require less silicone than pour molds. Splitting the mold into two parts can allow you to work around undercuts in a mold.
Note that you can add more than one mold part line, however this will increase the complexity of your mold.
In this Instructable I will be making a mold of a clay original that I sculpted and then creating a slush casting using the mold.
Materials I used include:
- non-sulfur oil based clay (6 lbs)
- clay tools
- dragon skin 20 silicone (2x trial kits)
- plasti paste mothermold
- mixing containers (x20)
- brushes (x2)
- stirring sticks (x20)
- gloves (a lot)
- smoothcast 300 (1x trial kit)
- mold release
- wing nuts
- 1/8th MDF board
- sewing tape measure
Step 1: Create design
Start by designing your part.
I had a mannequin head around, so I thought it would be fun to make up some sort of futuristic spacesuit helmet.
The first step is preparing the base model for fabrication. If you're using a base model that you don't want to get ruined with clay or mold material it might be a good idea to cover the model in something silicone friendly (note that silicone has a hard time curing on certain material surfaces). I covered mine in plastic wrap and tape.
The mannequin head was obviously not to human scale and I wanted the helmet to fit my head. So I found my head measurements using a sewing tape measure then, added clay to the mannequin's head until it matched my measurements.
Next I sketched possible designs over a template. I included the template file I used.
Once I drew something I liked I started building and used the drawings to inform what I made.
It might be helpful to draw these at full scale so you can compare what you make directly to the drawings.