Sandy King (sanking@hubcap.clemson.edu)
Wed, 21 Apr 1999 13:39:35 -0500
>
>> > 4. Can the sensitizer be brushed on rather than tray soaked?
>>
>> So I've read. I've never tried that.
>
>Klaus Pollmeier, one of the premier carbon printers of the world (so sue
>me, it's true), explained precisely how to do that, with detailed
>illustrations along the way -- can you guess where?
>
The sensitizer can be brushed on (called spirit sensitizing) rather than
tray soaked. There are advantages and disadvantages. The advantage of brush
sensitizing is that the tissue dries faster (in about 15 minutes, compared
to an hour with tray sensitized tissue). The disadvantages of brush
sensitizing are 1) the tissue requires longer exposures, 2) it is difficult
to get consistent results, 3) some uneveness often results, especially in
area of smooth tones, and 4) the alcohol or acetone used in spirit
sensitizers can melt the gelatin of the tissue, resulting in streaking.
If you still want to try spirit sensitizing I recommend that you use a foam
brus. Mix the dichromate (I recommend ammonium dichroamte for spirit
sensitizing) at about twice the desired strength with an equal amount of
alcohol or acetone, then brush over the tissue, first lengthwise, then top
to bottom, then on the diagonal. Let the tissue dry for about a minute,
then repeat. If you attempt this at temperatures much over 70 F the gelatin
will almost certainly melt. Use of a fan will greatly reduce drying time
(also tru with try soaked tissue).
I have made a lot of prints sensitizing with spirit sensitizers but
strongly believe that tray sensitizing gives on the whole better results.
DSandy King
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