Difference between Single and Multi-Part Molds

Making a one part mold is simple and straightforward. However, the technique does not work every time. Complex objects call for making the mold in parts and artists should know how to make multi-part molds.

The best way to duplicate an object or to reproduce it in another material of choice is to make a mold of it. This basically captures a negative impression of the model that can be cast into to make an exact reproduction.

Therefore, it is fairly obvious that making a mold is a preliminary step that serves as the base for building the final casting. Artists try to keep the mold making to the simple and basic by opting for single part molds. This is the easiest method as the mold making material has to just be poured over the model to form the mold. Different types of materials – both rigid and flexible - can be used for making the molds.

However, one part molds work only for simple objects that have a flat side or base. The flat portion can be affixed to the mold box before pouring the mold making material. Once the mold has cured, the model can be detached and easily pulled out of the mold.

Multi-part molds

Models that have complex shapes or too many undercuts make it necessary to make the mold in two or more parts. Similarly, models that do not have a flat base or are thin and floppy or have holes going all the way through them (like a baseball, donut or coffee mug) call for multi-part molds.

The prospect of making such molds is much more complicated and time-consuming. The trick here is to embed half (or a part) of the model in clay so that the mold covers only the part that is protruding outside.

Once the mold part has cured, the clay is removed and a parting line and keys are made on the mold. Provision for a pouring spout (like a straw) also has to be made before pouring the mold making material on the other half of the model.

Once the mold has cured, the mold is cut along the middle or the parting line until the model can be pried out successfully. The parts are then aligned again using the keys and the mold comes together to form a whole. It has to be sealed properly before pouring the casting material into the mold by way of the spout.


It is clear that the procedure of making two part molds is very different and complicated than regular single part ones. However since the simpler process will not work every time, professional casting artists need to become adept at making the multi-part ones too.

EnvironMolds offers all the materials, supplies, tools and equipment for making molds, casts and life casts. The website https://www.artmolds.com is overflowing with step-by-step instructions, tips and other handy information for making all kinds of molds, casts and life casts.

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