Tuesday, March 10, 2015

Figure Sculpture Process: What is a Mold?

Molds are used for many of our everyday household objects- the door knob, the plastic tabletop, your cup, your vacuum cleaner... evidence of the power of replication exists all around you!

There are so many different types and purposes of molds, and this post is going to explain some of the variety and how they are used in fine art.

What is a Mold For?
A mold is used to produce an exact replica of an object.

This could be to translate it into a new material with special properties- you could cast an object in rubber for flexibility, or concrete for durability. It also allows you to make multiples of an object. In sculpture, this is known as an edition.

Basic moldmaking at work is evidenced in the household ice cube tray. This simple mold gives us the ability to take a material, shape it, and make multiples. The objects that are created are called casts. This same principle is applied in fine art when making editions of sculptures.

How are Molds Made?

Making a mold is often a labour intensive, highly skilled process. An object will be covered in a liquid rubber which cures into a flexible material that takes a perfect impression of the object. (The rubber I use looks like liquid marshmellow. Mmmm.)

A fully round object will need seams to divide the rubber into pieces so that it can be removed. (this is the tricky bit!) The rubber is too flexible to hold its shape on its own, so a rigid shell called a mothermold  is applied: this is commonly plaster or fibreglass.

(Fun fact: Molds can also be made entirely out of plaster, however they need many more pieces as the plaster is completely rigid and cannot flex around the curves of the object.)

Common Materials:

Rubber (silicon or urethane)
Plastipaste (mixable plastic product)

Should I learn to Make Molds?

If you want to make replicas of things, the answer is Yes. If you are a sculptor, then the answer is ABSOLUTELY!

Here's why:
1) it will save you time and money to make your own molds
2) it will allow you to experiment with new materials
3) it will allow you to make replicas of your work (for sale, for family, for yourself, etc)
4) it is FUN!

Even if you decide moldmaking is not for you and prefer to hire a professional, having an understanding of the process will still result in a better end product:

1) it will allow you to communicate with your moldmaker with greater clarity and understanding
2) you will be able to create your sculptures in a way that makes molding easier, more efficient, more cost effective, and the finished casts more resilient.

(If you live in Victora, BC and want to learn about moldmaking- visit my  workshops page here and scroll  down for workshop opportunities)

Types of Rubber Molds:

When first learning about molds, there is alot of new terminology. You will discover that the terms are actually pretty straightforward once you learn their meaning. There are 3 common types of molds:

One- Piece: used for relief objects. No seam is needed to release the sculpture.
Split-Gloveused for simple objects in the round that need a seam only on one side. (imagine a jacket!)
Two-piece (or more!): used for simple or complex objects in the round that require the seam to completely divide the rubber into two (or more) pieces to release the object.

Methods of Application:
Block Mold
Brush Up Mold

These two common methods describe how the rubber is applied. One is poured, the other is brushed on in layers.

You combine these terms to describe the type of mold, for example: One Piece Block Mold or a Two Piece Brush Up Mold.

To learn more about these types of molds, keep reading Figure Sculpture Process: Types of Molds