PRATT CENTER FOR CONTINUING AND PROFESSIONAL STUDIES
Product Design Joel Wennerstrom, Instructor
Email: jwenner@pratt.edu WEB: http://mysite.pratt.edu/~jwenner/
METHODS OF WORK: MODELS AND MATERIALS
In order to convey your ideas to others, you must develop skills in visual communication.
Drawing is used to quickly get ideas on paper so that you can visualize them more
clearly and allow you to further expand on them. But soon after that, a three
dimensional model is needed to verify your ideas and to explore form and ergonomic
concerns. Designers use many types of models and materials to verify their ideas, and
there are two main categories of models:
Working models are used to test mechanical or electronic features where function is
more important than form. They can be made out of any materials needed to prove the
concept- toothpicks, hot glue, cardboard, plastic, duct tape, wire, circuit boards, etc.
Form study models are used primarily to explore shape and comfort, and even
manufacturing concerns such as moldability. It is common for designers to do a working
model to prove a concept is mechanically sound, and then do a series of non-working
form study models to explore form variations of the concept.
Materials for form study models include wood, plaster, clay, paper and plastic, but the
material most commonly used is foam because it is lightweight, easy to carve, sand,
shape, drill, finish and paint.
Designers use three basic kinds of foam: urethane foam, phenolic resin foam (Balsa
Foam) and styrene foam. From the instructor’s point of view, there is little difference
between urethane foam and Balsa Foam, so I’ll discuss those at the same time:
URETHANE FOAM AND BALSA FOAM:
There are many kinds of urethane and phenolic foam. They vary in density, color,
texture, cell structure and price, though all of them are expensive.
Advantages: Easy to carve, sand, cut and saw with hand tools. Can be sanded in any
direction; has no grain. Can be put in oven at low temperatures (200 degrees). Does not
disintegrate when exposed to solvents and paints. Can be used with solvent-based or
water-based finishes and fillers. Dust is not considered to be toxic (that we know of).
Disadvantages: Expensive. Only specialty stores carry it, such as model supply
stores. Can order it directly from manufacturers on-line. Somewhat difficult to cut with a
utility knife, depending on density. Cannot use hot wire to cut.
STYRENE FOAM:
Styrene foam comes in one density, but varies in size and thickness. Comes in two
colors: pink and blue. Used for the building industry as insulation material.
Advantages: CHEAP! Readily available from art and building supply stores. Can use
hot wire to cut.
Disadvantages: Static dust clings to everything. Melts when contacted by solvents and
spray paint. Must use water-based paints and fillers. Difficult to sand until you get the
hang of it. Melts at low temperatures. Fumes when melted are said to be toxic, as is
dust when sanded. Use of respirator is suggested when sanding and wire cutting.
BUYING BLUE (STRYRENE) FOAM:
Blue foam is a building material used for insulating walls and floors and is most often
used in new construction. Therefore you will not find it in Manhattan or at your local
hardware store. But you can find it at building supply stores such as Home Depot and
Lowes, and there are many of these in the boroughs. Blue foam and pink foam are
practically identical except for their color and their manufacturer (Blue foam is made by
Dow Chemical and Pink foam is made by Owens Corning).
When you are in the store, look for it in the building insulation area, amidst the rolls of
fiberglass insulation. Store clerks have been known to deny having it at all if you just
ask for “blue foam”. It’s easier for them to say “no” than to try to figure out what you
really mean. Once you find it, you can get a 2-inch by 2 foot by 8-foot sheet for under
$14. 1 inch thick is about half that price. One sheet will be enough for 3 or 4 of you for
the whole course. You can cut it into easy to carry pieces with a knife. Those of you
who have no place to work in your apartments might want to bring your work into Pratt
and work in the woodshop near the exhaust fan- open all night!
You can also buy small pieces at the Pratt store or any number of art supply stores
(Apple Art, corner of Hall and Dekalb), but they jack up the price quite a bit. The
quality seems to be a bit better- more consistent in density, but it’s really the
convenience of having it in smaller pieces that you’re paying for.
You can buy blue foam and other types of professional model making foam from D&B
Supply at 109 Putnam Ave. Brooklyn, 11238 (718)-230-5642. Call first, as they have
odd hours and sometimes take the morning or afternoon off.
In order to save money and aggravation throughout this course, I suggest working
in blue foam for your rough models, then working in urethane or balsa foam for your final
models.