This is part 2 of a series of moldmaking posts. Read What is a Mold? here first.
Let's talk about two types of molds used in fine art reproduction, and their benefits and uses.
This is produced by creating a retaining wall around your object, and then pouring liquid rubber into this "box" to cover it. The result is a thick rubber mold.
The advantages are speed and ease as pouring the rubber is fairly quick and often no mother mold is needed, the disadvantages are cost (using more rubber is costly).
Here is an example of a finished one-piece block mold for a small relief sculpture (note: this was a quick and dirty mold, so it's not the prettiest example.) This is actually a negative of the sculpture, but in the pictures it can look like the face is popping out towards you.. trippy optics!!
Brush On Mold
This is produced by brushing layers of liquid rubber over your object to create a thin skin. Usually 3 layers is enough. You can do this for one piece, split glove or two piece molds.
The tricky part is deciding where to put your seams to have the best release and the least amount of finishing work to do, what types of seams to build, and how to register... this is a whole other blog post!
Advantages of this style are it is most cost effective than the block as you use alot less rubber, however, it is significantly more labour intensive as you must apply separate layers and wait for each one to cure. You also need a mothermold, as otherwise the rubber would be too floppy.
Here is an example of a simple two-piece brush on mold in progress: the first layer of silicon applied, and the seam (also called the flange) shown here using cards.
For a full step-by-step of the two-piece moldmaking process, visit Two Piece Moldmaking Process post here)
After the mold is made, a whole other process comes into play: Casting!
This refers to creating your first replica out of the mold, and can be done by pouring in liquid, brushing in thicker liquid, etc. More on this in another post!
If you read this far, congratulations! You now know more about molds than most people. Pat yourself on the back!
Molds are a behind-the-scenes process. By bringing this process into the light, it gives a deeper understanding of what goes on to create the finished sculpture you see. Often the first step of creating the work in clay is just the beginning! Understanding the journey taken from the clay to a finished product illuminates just how labour intensive sculpture can be, increases your appreciation of the craftsmanship, and perhaps also of the pricetag.