Re: Mylar as base for carbon tissue

Philip Jackson (pjackson@nla.gov.au)
Mon, 22 Apr 96 12:31:00 PDT

>From: s carl king <sanking@hubcap.clemson.edu>
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>Some months back there was a thread on making carbon tissue. Several
>people on the list mentioned that Mylar could be used as a base,
>including me, because a couple years back I coated 10-20 sheets of
>tissue on this base without any problems. More recently however I
>purchased some Mylar from Light Impressions and encountered a major
>problem, mainly that the coating simply peeled off the base when it
>dried. Does anyone have any idea how this might be avoided? Would like
>to hear from those who have been using polyester bases for coatings.

I've experienced this problem - it's caused by something to do with the
surface tension differences between the two materials. They bond all right
when they're wet, but as the gelatine contracts when it dries it pulls away
from the polyester base. I'd suggest (1) adding more plasticizer to your
carbon tissue mixture - say up to 5% glycerine (or use the plasticizer in
Mike Shorter's formula posted by Pete Frederick); (2) lay down a substratum
on the mylar - say plain gelatine plus plasticizer with a chrome alum
hardener; or (3) use mylar already coated with gelatine - either unexposed
film that's been fixed or washed (Kodak 4125 worked for me but Aristo Litho
didn't) or better yet, Kodak roller transport film - it's polyester already
coated with soft gelatine and is used for cleaning automatic processors. A
box of this isn't cheap, but you can probably find somebody who'll give you
a few sheets to try.

Philip Jackson
pjackson@nla.gov.au