Re: Carbon Was: Re: Collotype

Luis Nadeau (nadeaul@nbnet.nb.ca)
Tue, 16 Jun 1998 20:49:57 -0400

At 10:03 PM +0200 98/06/16, Klaus Pollmeier wrote:
>Sorry for this late answer to a mail allready two weeks old. Just
>thought my experiences might still be interesting.
>
>Sandy King schrieb:
>
>> I
>> have on several occasions worked with aged Hanfstaengl tissue claimed to
>> have been kept in frozen storage. Even if so, the B+F was very high, in all
>> cases over .30.
>
>I would be interested to hear where and when you got it and what type it
>was. The Hanfstaengl papers #19 (violet black) and #20 (olive black)
>coated in 1991/1992 still are in good condition. I don't have a fog test
>at hand but if sensitized and used carefully they show no visible fog
>(certainly less than .30)

I and others who bought some of the "frozen" materials in the 80s from the
then US importer (Green) experienced a lot of fogging. I don't know about
the more recent material you are talking about.

>> I am curious as to what Autotype and Hanfstengl added to their
>> gelatin/pigment mixture which led them to believe that it could be stored
>> indefinitley. Any comments appreciated.
>
>Hanfstaengl added nothing to it except gelatin, water, aquaous pigment
>dispersions and a wetting agent. Sorry, I am not allowed to publish the
>exact formulas.

McGraw didn't add anything either, but the scientific and patent literature
does mention the use of additives to prevent the hardening of pigmented
gelatin.

Luis Nadeau
NADEAUL@NBNET.NB.CA
Fredericton, New Brunswick, Canada
http://www3.nbnet.nb.ca/nadeaul/