From: Richard Knoppow (dickburk@ix.netcom.com)
Date: 05/13/00-05:58:58 PM Z
At 10:43 PM 05/12/2000 -0700, you wrote:
>
>
>"Christina Z. Anderson" wrote:
>
>>
>> Interesting: we had a student in the class I was TA'ing for bring us a
>> print which came out of our roller dryer REALLY glossy. It looked like hi
>> gloss RC as a matter of fact. In comparison with the same print on the
same
>> paper it was really amazing. She swore up and down it was fiber paper, but
>> it seemed really flimsy and we couldn't figure it out. Finally I got it:
>> it WAS fiber paper, a thinner Kodak brand, and the roller had apparently
>> been turned up too hot that day and had made the print shinier, a sort of
>> inadvertent ferrotype.
>> Chris
>
>One of the reasons it's hard to find a pako drier with a good surface is just
>the opposite of what happened here. My college routinely had the heat up to
>the 225 range and at least once a semester someone would put an RC print thru
>it. If we caught it in time it would only bond/melt with the drum, and
someone
>would take a metal spatula and then steelwool to the drum to remove the
>remains. Once we had a print bond fabric to the drum (sort of like hot
>mounting tissue does to prints & matboard) Had to get a whole new apron, and
>sure enough they took the old one all the way off, so it took me the better
>part of two hours to figure out which side of what roller the apron went on.
>
>If you have access to one of these I've found if the heat is below 175, RC
>paper comes out unscathed.
It makes sense that any temperature which is safe for dry mounting
should do no damage to the print. By memory the temperature for Colormount
tissue is around 140F.
The extra hot roller reminds me of a thread somewhere about drying
prints in a microwave oven and getting very glossy results. Probably, the
gelatin overcoating melted and flowed a little.
The ferrotype plate essentially calenders the gelatin surface of the
paper. If the gelatin is softened by heat it will be more effectively
calendered. The gelatin surface will be a reflection of the surface its
dryed on, so the shinier and smoother that surface, the glossier the print.
I have metal ferrotype tins which have a dull surface and make dull looking
prints. They were that way when new. Good ferrotype plates are the
brightest polished chrome, not the duller type which seems to be widely sold.
Excessive heat, either in drying or in mounting can also change the
image color of a silver print. The actual crystal structure is changed. If
it goes far enoughy it results in an effect known as "plumming" where the
whole image, or parts of it, turn a purple color.
I should not have to point out to this group that the term "ferrotype"
has another, much older, meaning refering to a direct positive process
similar to the "tintype".
---- Richard Knoppow Los Angeles,Ca. dickburk@ix.netcom.com
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