On Tue, 26 Aug 2003 10:27:10 -0400, "Ron Natalie"
wrote:




There are several kinds of polystyrene insulation board. Usually
referred to as Styrofoam and Styrofoam SM in the construction trades
up here in Canada.

Dow's trademark Styrofoam applies strictly to extruded polystyrene (and
in Dow's case it's blue, also a trademark of Dow). The pebbly white stuff
used for coffee cups and coolers is expanded polystyrene and is a misuse
of the trademark.

Check your facts. Dow made and sold white expanded "beadboard"
insulation under the Styrofoam label for years in Canada, and then
introduced Styrofoam SM rigid foamboard to the market. The SM was to
differentiate between 2 products.I believe Morval Durofoam used Dow
supplied styrene to produce the blown foam coolers and other "expanded
styrene"" products . They now also have an SP.

Dow Styrofoam is also used in crafts, where it is white. See:
http://www.dow.com/craft/index.htm

Also see: http://www.glacierbay.com/dowtest.htm where it states: "Dow
Chemical's "Styrofoam" brand name encompasses a wide range of
polystyrene-based insulation products. Included in our testing were
two versions, the common white "expanded" product and the "extruded"
Styrofoam Square Edge (see photo).

Styrofoam (expanded)- This is the product most people think of when
they hear "Styrofoam". It is white in color and comprised of
thousands of individual "beads" which are pressed together. The most
common use is as a cushioning material in shipping and packaging.
Although it is not intended for use as an insulation, it frequently
is. Most people have seen cheap coolers and ice chests made from it.
As an insulation, expanded Styrofoam has many qualities which count
against it. At R 3.84 per inch, the product is simply not a very good
insulator. Secondly, it is very hygroscopicity (absorbs and holds
moisture). This tendency to get, and stay wet, makes it something
to definitely avoid when looking at ice box insulation.

Styrofoam Square Edge (extruded) - This product is often called
"blueboard" due to its light blue color. In spite of its relatively
modest "R" value (4.92 per inch), Styrofoam SM is our overwhelming
recommendation for foam ice box insulation in marine applications.
Unlike its expanded cousin (above)and virtually all other foam
insulation, Styrofoam "Square Edge" is completely impervious to
moisture. This is a huge plus. While many other foams start out as
better insulators, they inevitably suffer significant decline as they
absorb moisture from the surrounding air. This is not the case with
Styrofoam SP. Another benefit of its hydrophobic nature is that no
"air gap" is required when installing it. This means that more
insulation can be packed into a smaller space. If is available in many
thicknesses and two sheet sizes."