What comes to mind when you hear the word foam? Styrofoam? Packing foam? Foam rubber? There are as many different kinds of foam as there are varieties of bread.
In fact, foamed plastics are similar to bread in several ways. Bread is made by mixing a number of ingredients like flour and water and yeast. The yeast makes bubbles that make the bread rise.
Foam is made by mixing a number of chemicals and adding a "gassing agent" that makes bubbles that make the plastic cellular.
Bread has to be baked in a stove, but foamed plastics are heated from within- the heat comes from the chemical reaction. When the block of foam has finished rising, it's called a bun of foam just like a bun of bread.
Theoretically, there are as many different kinds of foam as there are different kinds of plastics. But practically speaking, there are only three families of foamed plastic used for sculpting.
Styrofoam, actually a brand name of Dow Chemical, is the insulation foam, usually blue or pink, that you see on the sides of buildings under construction or renovation. This foam is technically known as extruded polystyrene. The other styrofoam is a white packing foam made of tightly packed beads of foam. That's why this expanded polystyrene, or EPS foam, is also known as beadboard foam. Both types of styrofoam come in a variety of densities and can be sculpted using hot-wire tools.
Rigid urethane foam is the foam that you'd find at the bottom of a floral
arangement. It comes in a variety of colors and densities. The lower
densities (3-10 lb/cubic foot) can be sculpted with conventional sculpting
tools. The higher densities (up to 60 lb!) are more easily fabricated
using routers, dremels and milling machines. Hot-wire tools cannot be used
on rigid urethane foam!
Flexible foams comprise the third category and include Polyethylene foam,
which you'd find on the bottom of your sneakers and flexible polyurethane
foam, used in mattresses and nerf balls.
The foam, or combination of foams, that FOAM PROPS uses for a particular project depends on several variables, including the desired size of the object, budget constraints and the amount of detail involved.
And why would you use foam instead of wood or other sculpting materials? Above all,foam is fast. We can create a foam sculpture in a fraction of the time it would take to carve a standard sculpture. Plus, foam is easy and fun to sculpt.
And with the addition of a hard plastic coating, our foam sculptures can be very lightweight and reasonably durable. Of course, if durability is the main concern, we can pull molds from the foam sculptures and cast fiberglass reproductions.
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