used to make prosthetics has quirks and idiosyncrasies, foam latex is probably the most difficult material to work with overall, from several perspectives.
First, foam latex is opaque. You can't see through it. Unlike silicone and gela tin, which can be colored intrinsically to be semitransparent or translucent, just like real human skin, foam latex is naturally opaque. To create the semblance of translucency, the appliance must be painted with numerous transparent layers ofpigment, usually with an airbrush, to achieve the look of real skin.
Second, foam latex requires a heat cure in an oven, and it cannot be the same oven you use to bake tollhouse cookies and Thanksgiving turkeys!
Why? Because third, foam latex gives off toxic fumes during the heat cure that will render your oven forever unfit for cooking. There are a few alternatives, one of which is building your own makeshift oven using infrared heat lamps in a well-insulated plywood box. I can show you how, if you're interested. I am now using an old GE consumer oven that I rewired from 220v to 110v. It's not very large, but Ican fit a two-piece mold for a full-face appliance and two smaller molds
in it pretty easily. I might be hard pressed to get a full bust mold for an over
the-head cowl in it, but it has served its purpose well, and Icouldn't pass up theFIGURE6.12
A rescued kitchen appliance makes a terrific foam latex oven for small to medium sized appliances. Photo by the price-free-when a neighbor remodeled his kitchen and asked me if Ihad any . use for his old oven. (On the plus side, Iget pretty terrific results with it.)
Whatever you use as your latex oven, your foam latex should cure in an oven that cannot exceed a controllable/maintainable 200°F. Ideally, foam should cure no hotter than 185 oF (85 o C). I frequently cook it at 170 o F (about 77 o C) for a lon ger time, as I will describe a little further on.
Foam latex is time and temperature sensitive. When I was first learning how to run foam, I remember mixing the foam according to the instructions for using GM Foam and watching the foam solidify in midpour from the mixing bowl into the mold. D'oh! It was like watching a cartoon.
Foam latex shrinks. The thicker the foam, the more it shrinks. That's not to be con fused with the volume of the foam; lower-volume foam (heavier) will shrink more than high-volume foam (lighter) because it has more air and a lesser proportion of foam latex components. It is water loss that causes shrinkage in the foam. Since higher volume foam stretches more than denser low-volume foam, any shrinkage that does occur can usually be compensated by stretching, with little force exerted on the foam.
What the mold is made of also contributes to the shrinkage of the foam or the lack thereof. A porous mold like Ultracal will cause the foam to shrink less because it absorbs moisture from the foam.
Foam latex, being essentially a foam rubber sponge, will collapse into itself when it moves, such as with a fold of neck skin; silicone appliances displace