"toller" wrote in message
...
My neighbor threw out a 6' diameter hottub cover, presumably because the
fabric covering had a small cut in it. It is entirely styrofoam.

I was thinking of using it either as a swimplatform at the lake, or as
floatation for a wood swimplatform. The manufacturer recommends against
it; although the covering is nominally waterproof (well, after I patch the
cut) the styrofoam will eventually absorb water and become useless.

Is that true? Styrofoam is used for boyancy in boats and it doesn't
absorb water, but maybe they waterproof it somehow. (wouldn't you think a
hottub cover would be waterproof?)


Styrofoam is Dow Chemical's brand name for their blue extruded insulation
board. You may have that or something else often mistakenly called
styrofoam. White expanded polystyrene is often called that by error. Over
time, it can absorb some water. A well fused well made piece is fairly
solid when skinned over, but it is made from a cellular structure in the
material. Once the cell open or the interstices are opened, water can get
in.