Lab: Waste mold of a hand

For the first of two weeks on molding and casting, we made waste molds of our own hands.  Waste molds are usually not reusable; hence, the material is thrown away after just one use, which is far more wasteful than other mold methods.  However, waste molds are very easy and can be extremely detailed when the proper technique is observed.

Only two materials are needed to make this mold.  The first is alginate, a naturally-derived substance that absorbs water quickly.  Powdered alginate is mixed with an equal volume of water to create a gelatin-like substance that takes the impression of the object to be casted.  It's important to coat the object to be casted in a mold release agent (in this case, Vaseline) which enables the object to release from the alginate without damaging the mold itself.

This negative is called the mother mold, and it is into this mold that the second material, plaster, is poured.  Once the plaster sets, the mold is removed from the container, beginning the detailed process of cutting away the alginate from the surface of the plaster cast.

The reason that my cast was not of my whole hand was that I did not make enough alginate for the mother mold.  When I put my hand in the alginate, there was only enough to cast up to my knuckles. However, I do like how the finished cast turned out.

The level of detail this type of mold affords is quite remarkable given the total effort required. If you did everything as fast as possible I think you could completely finish a casting like this in about 40 minutes.