The reverse *is* recommended for film -- I've done it in the past with
microfilm during surveys of old masters, but it hasn't held true...I don't
know why that would be, though.
Because our interest is stirred here at WHS, we're going to start testing
with polarizing filters vs. looking through the pack to see if it holds up,
as we reformat. Will report back!!
>In many collections, you CAN rely on the box as your first source of
>information. The easiest thing to do is to hold the tape up the a strong
>light. If you SEE light coming through the tape pack (the 1/4-inch
>dimension) i.e. through the edges of the basefilm, then it is acetate. I
>understand this is reversed for film, but if you take some Scotch 111
>(very common acetate tape) and hold it up so you're looking at the disc
>of the reel, you'll see light coming through.