Judy Seigel (jseigel@panix.com)
Tue, 16 Mar 1999 21:29:45 -0500 (EST)
On Tue, 16 Mar 1999, Sandy King wrote:
> For reasons which I don't fully understood, but have commented about
> previoulsy, in my working conditions I routinely require much weaker
> sensitizer than those recommended in most of the literature. This in spite
> of the fact that I have worked with a number of different gelatins and
> dichromate solutions, and always make tissue and sensitizers with distilled
> water. To give you an idea, these are the typical strength sensitizer
> needed for negatives of a given density range.
>
> DR .8 - 1.0 1/8%
> DR 1.0-1.2 1/4%
> DR 1.2-1.5 1/2%
> DR 1.5-1.8 1%
> DR 1.8-2.2 2%
> DR 2.3+ 3% and up
>
> I have not experienced any uneven sensitizing with these very weak
> sensitizer, and I don't do anything special. I sensitize by soaking in an
> open tray for 2.5 minutes, then squeegee out the excess dichromate
> (emulsion side down) on a clean sheet of plate glass, and place the tissue
> on a drying rack to dry. Drying is accelerated by directing the air from a
> fan a close distance over the surface of the tissue.
As I understand it Sandy, some printers hand-apply sensitizer, which would
probably be a factor. Also, maybe your gelatin is softer, or hardened
less, takes on more solution? Or gelatin sensitizes better less hardened?
> I am currently printing with 350na BL fluorescent tubes. For a couple of
> years I used GE Daylight tubes, which required an approximate 2X increase
> in sensitizer strength to give the same contrast.
Any particular reason for switching back? Just the change in sensitizer,
or....? You make me curious.
Judy
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