I've found that the triacetate tape used by Kodak and perhaps some others is
much less translucent than regular acetate, especially the "long play" types.
It is hard to distinguish from "Estar" except in a side-by-side comparison.
Film base was sometimes dyed to reduce halation effects so its transparency
However, in general, if light goes through the pack, it is acetate. Another
test, to try on an inch or so of an end, is that if can be stretched, it's
polyester. Some of the tensilized polyester doesn't stretch much though.
Sent: 12/27/2007 8:56:29 P.M. Eastern Standard Time
Subj: [ARSCLIST] polyester or acetate? (complete)
sorry, the previous post didnt get through correctly, here the full version:
Due to a recent experience with an historical sound archive, I am trying
to get some insight into the details of aged magnetic tape and tape
preservation. I thought I had this right but now I am confused by the
description the literature does relating the methods that are used to
distinguish acetate from polyester tape. At first I had understood that
acetate is tranlucent when held agains the light, and here are some quotes
that support that:
"almost all post WWII acetate tapes, you can hold them up to the light and
see light through the edges of the tape pack."
"All standard play, most long play, and some double play acetate tapes
have a translucent wind when held against a light source. This is not the
case with PVC or polyester tapes." quoted from a technical paper found at
however when I finally got to read what seems one of the most quoted
studies on the topic (IPI Storage Guide for Acetate Film, p 21) I found:
"When viewed "edge on" (holding the reel up to a light source and looking
through the spokes of the reel), polyester film will transmit much more
light than acetate or nitrate (see fig. 20). some light will pipe through
the edges of the film with acetate, but polyester will look much
and fig. 20 shows 2 tapes, and the footnote says:
"When held up to a light source the polyester film "pipes" the light
throught the edge of the film, while acetate and nitrate do not.
(polyester film shown at right)"
and the tape of the right indeed lets more light through!
In my archive I found both translucent and opaque tapes but now I am
confused.... any comments?
Thank you for your help
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