Dear Karen --
Sorry this response is so delayed -- I'll spare you the explanations/excuses,
and just offer my apology. I realize that the issue may no longer be timely,
but here's a reply anyway.
Virtually any polarizing material will work. Thickness and color are really
pretty arbitrary. I personally prefer the green or gray to the brown, but it
really isn't crucial. As for thickness, unless you had something so thin that
it was fragile and awkward to work with, it again doesn't make much
difference. Ordinary posterboard looks to be about a quarter of a millimeter
thick as best I can tell by eye with a ruler, and this would be thick enough
for Polaroid material. I looked in the Edmund "Scientifics" catalog, and the
"Commercial" grade is 0.74 mm, or three times as thick, which would be fine.
The "Experimental" grade is specified as 0.015 or 0.010 inches, which in
millimeters is about half as thick or a third as thick as the Commercial
grade -- or seemingly about the thickness of posterboard. So I think any of
them will work fine.
For the past several years at the Exploratorium Teacher Institute, we've
bought Polaroid material either directly from the Polaroid Corporation (but
they were recently bought by someone else), or from another company whose
name escapes me as I write this -- but in either case we purchased in bulk,
and I don't think they sell single pieces. I don't know how much you need --
or whether you've already obtained it, and in fact don't need it at all any
more -- but if it's just a couple of one-foot square pieces, let me know and
I'll check our supply and possibly we can just give it to you as a fellow
musem if our supply isn't low (incidentally, where is the Cabrillo Marine
Aquarium located?! -- Santa Cruz? San Diego? ...??? -- let me know if you're
interested, and also the mailing address if so). (Also, in case you're
wondering why I don't check the supply before sending this, I'm writing this
from home, and I'm not at the Exploratorium every day.)
This may be more than you wanted to know, and later than you wanted to know
it, but hope it helps. Again, sorry for the delay.
Sincerely,
Don Rathjen
Exploratorium Teacher Institute
donr@exploratorium.edu
or
donrath@aol.com
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