Difference Between Mold Making and Casting

Molds and casts have emerged as popular and accepted art forms for reproducing a sculpture, artwork or almost anything else. Indeed, using the basic techniques of mold making and casting, it is possible to recreate just about anything in its entirety. A variety of products and materials can be used based on the requirements and it is even possible to replicate the live human body. You can easily create a spitting image of a person’s face, hands or any other part you wish!

However, a layperson often gets confused between the two terms of mold making and casting. The following explanation will shed clarity on the methods and help you to understand them:

Mold making: A mold is nothing but a negative or reverse impression of an object or sculpture. It accurately captures the surface detail of the object right down to every fold and undercut.

Molds can be made with different materials such as clay, wax, plaster, moulage, polyurethane rubber, silicone rubber, thermoset mold rubber, liquid latex rubber and more. Plaster bandages yield rough form molds and are generally used to make supportive shell molds. Body molds are usually made with alginate as it is skin safe.

Similarly, there are various techniques of making a mold – ranging from simple to complex – depending on the type of object, mold making material being used as well as the proficiency of the artist. The techniques are divided into two basic categories – block mold and blanket mold. The material is usually poured or brushed on the object to form the mold. Injection and slush are other methods of making a mold.

Making a single part mold will suffice for simple shaped objects with a flat side, while objects with more complex shapes and undercuts require two part or even multi part molds. While most molds can be used multiple times, some such as alginate molds are single-use molds.

Casting: This is the subsequent step after the mold is ready. This is the actual method of reproducing identical copies of an object or sculpture. However, it requires a negative impression in the form of a mold to work on.

The casting material is usually poured into or onto the mold to form the final cast reproduction of the object. Depending on the type of mold, it is often possible to make multiple cast reproductions from the same mold.

Casting is open to a wide variety of materials such as plaster, gypsum, epoxy resin, polyester resin, polyurethane resin, liquid latex rubber, urethane rubber, silicone rubber, molten metals and more. Alternatively, cold casting powders can be mixed with resin to duplicate the look and feel of real metal.

At times, the same type of material can be used for both mold making and casting – such as liquid latex or silicone rubber. However, it is important to note that the liquid latex or silicone rubber will be formulated differently to suit each application!

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