Plaster bandages are used with alginate to give the alginate a rigid structure when doing a layup mold.
In face casting, a thin layer (1/4 inch or so) of alginate is applied to the face. If that alginate was removed from the face without the plaster bandages, it would flop around like a deflated balloon. WITH the plaster bandages, the face mold comes off looking like a bowl with a face inside and does not flex or distort when being poured with casting material.
Larger molds require thicker, more rigid plaster bandage shells, so more layers are required.
A box contains 12 individually wrapped rolls.
Quick-setting (5 minutes) plaster bandages appropriate for reinforcing layup alginate molds like faces, heads and torsos. These are also ideal if you just want to make a plaster bandage casting of a pregnant belly and skip the alginate portion altogether.
Plaster Bandages are strips of gauzy cheesecloth type material that have been impregnated with plaster. They come in 5 yard (15 foot) rolls. We carry the two most commonly used sizes 3-inch and 4-inch wide rolls.
We purchase these in large quantities so we can pass on the low price on these high quality bandages to you
The common wisdom is that the larger the mold, the stiffer it has to be. This means you will need more layers of plaster bandages for a torso mold than for a face mold. One of the worst things that can happen to an alginate mold is that it bend, twist or collapse during the pour-up phase- which could very well ruin the mold. Since larger molds are heavier and require larger amounts (weights) of casting material, they need to be quite a bit stronger than smaller molds.
For full body castings, most operators will embed long pieces of wood in the plaster bandages. Usually a 2x4 ripped in half lengthwise is sufficiently strong for this. The wood touches the casting at the ankle, knee, hip and shoulder and is attached to the plaster bandage shell with more plaster bandages. Two or more of these reinforcing boards are used to ensure that the mold remains rigid.
A word of warning here. Make sure that plaster bandages don't touch the model's hair without having first applied a good release like Vaseline.