Can you make multiple 2-part molds at one time?

Can you make multiple 2-part molds without having to remove the clay and take the walls apart and the clay out? Or do you have to repeat the whole process every time if you want to create more than 1 mold of the same model?

Paige Russell4 months ago

Hi bbailey,

To achieve the best registration results, it is better to make one complete mold at a time.

You will always have to remove the walls in order to get the first half of the mold out (without disturbing the model and sprue/air hole) and if you remove the model from the first half of the mold in order to pour another first half, you will lose the seal between the model and silicone which will result in a small air gap which has the potential to get filled with material from the second half pouring.

To avoid this, you would have to fill it with clay, which is time consuming, and it will become a raised ridge on your finished cast piece.

If you want to make more than one mold, a good time saver is to be very careful when removing the clay from the first half, so you can reuse it with minor touch ups for your second mold.

Another option is to use the first mold to create a 'mother mold' for each half. This means you would make a mold of each half of your two piece mold (think of each half as a new model), so you can cast as many molds as you'd like that way without having to redo the whole mold making process every time. This will require making a multiple part mold for each mold half.

This instructable by alepalan shows you the basics of 3-part mold making:

Let me know if you have any more questions!


To make the explanation short: as Ms. Paige says, registration are fundamental for getting the right mold. Once that is done and the mold has been done in one side, you can remove the opposite side carefully to avoid loosening the side already made. The new side has to be clean thoroughly and de-molding or release agent, properly sprayed or painted all over the first side. Then you pour your second side and repeat the operation again. By experience I could say that you most probably can do it up to 4 times before you start to detect that in some areas there are signs of leaks or one side moves. All this process require a lot of patience and expertise but it can be done.