The Molding and Casting Approach to Making Replicas

Mold making and casting together form an efficient process for reproducing almost anything. There are clear differences between the two techniques and artists should know the ins and outs of both.

The most common method of making an exact three-dimensional replica of an object is molding and casting. In fact, most of the everyday items that people use in their homes and offices have undergone the molding and casting process.

Mold making


The mold forms the first step of making the replica. This is a hollow cavity of the shape of the model or master that is to be reproduced. It is also considered as a negative of the desired object.

Molds can be made with different materials and there are various techniques for the same. While anything like clay, wax, resin, silicone rubber, polyurethane rubber or thermoset mold rubber will lend itself well for making molds, the general consensus is that molds should be made with flexible materials as this makes it easier to demold the cast.

When working on molds, the mold making material has to be mixed properly and may even require a vacuum pump with vacuum chamber to ensure that it is free of air bubbles.

The best part about molds is that most of them are reusable and can be used for making multiple casts. But keep in mind that while some molds lose their shape quickly and are good for single castings only, others will also have a limited shelf life and will start to deteriorate with time.


Casting


While the mold is the first stage, casting forms the final stage that delivers the finished replica of the original model. A casting is usually made by pouring the casting material into the hollow mold. It is allowed to cure and then extracted to obtain the final product. This can be sanded, painted or finished as desired.

Here again, there are different techniques for casting and varied materials lend themselves well for the casting process. Yet, in general, it is better to use materials that cure to a hard form as this ensures efficiency in the process and durability in the final cast. The materials that are commonly used are plaster, gypsum, concrete and polyurethane resins apart from an assortment of rubbers. A vacuum chamber may again be required – especially for rubbers – to ensure that the cast is smooth and blemish free.

As the casting is the finished product, it obviously cannot be used in the process again and again. However, at times, casts are used to make secondary molds as they already hold the desired shape.

In sum, mold making and casting are used in conjunction to make duplicates of varied items. The have their own inherent characteristics and artists have to familiarize themselves with all the features before attempting to use them. These processes can also be used for other purposes like mask making and doll reborning. Life casting also draws on this to make reproductions of the live human body!

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