Clean Clay, Hot Glue and Foam Core. All of my best friends when it’s mold makin’ time. Each piece got a final smooth down, and a light spray of Crystal Clear this works as a mold release. Everyone has their favorite material to make mold forms, I love foam core. It’s relatively cheap and easy to cut and shape to economize the size of the mold.
First part the legs / foot base. Using a dab of glue to secure it to the foam core base. Secure every part, nothings worse than having a part decide to start floating when the silicone is poured.
I’ll score the back of a long strip of FC to make the wall, hot glue it down. One down 10 to go! There are a few different types of molds. The foot base would be a one piece with no relief cuts. It will pretty much be like pouring the resin into a bowl. The second kind I’ll be creating for the feet.
mark the cut line. When the silicone is set I’ll remove the foam core, find the find cut marks and cut along that line to remove the clay piece. I’ll rubber band it together when it comes time to cast.
Third kind I’ll be doing here, a two-part mold where I’ll use Clean Clay to create the separation point and the keys.
The body is a good piece to demonstrate. I don’t want the detail of the bottom of the shirt to get damaged I raise the piece up with a few blobs of clay underneath. Now build up the clay separator. Remember this will be the thickness of the mold wall. Too thick you’re wasting valuable silicone, to thin the mold won’t hold it shape.
Getting a nice edge at the point where your clean clay makes contact with the sculpt is important. It will greatly affect weather you will have a nice tight fitting mold, or one that will cause you to have to do lots of clean-up on your finished casting. I’ve seen a couple of mold making videos by the companies that make these DIY mold / cast materials. The way they just kind of “plop the clay on” to create the divider is deceptive! I’ve made a little drawing.
Using sculpting tools, and a small paint brush with alcohol carefully push the clay right up to the edge of the sculpt, get rid of any excess, and make straight clean joint between the Sculpt and the clean clay.
Now that it’s all clean and shiny it’s time to make keys!
These will be the registration points that will make sure both halves of the mold fight snugly together. I make quite a few, first some big anchoring holes then smaller ones to take up the rest of the space
Again I cut out a long strip of FC fore the wall and score so it’s all bendy. I make the walls a few inches taller then the piece just so there’s extra room. I have to drive to a place to make my silicone, if I’m driving back with filled molds there’s some slosh room.