[pure-silver] Re: Old Paper Developer Question
- From: Richard Knoppow <dickburk@xxxxxxxxxxxxx>
- To: pure-silver@xxxxxxxxxxxxx
- Date: Tue, 19 Feb 2008 05:14:55 -0800 (GMT-08:00)
-----Original Message-----
>From: BOB KISS <bobkiss@xxxxxxxxxxxxx>
>Sent: Feb 19, 2008 4:45 AM
>To: pure-silver@xxxxxxxxxxxxx
>Subject: [pure-silver] Re: Old Paper Developer Question
>
>DEAR DON,
>
> As hoped, Richard has covered the fogging question rigorously.
>
> If you are referring to "risks" to the prints, I don't believe
>there are any risks with the mild fix-bleach-fix system. Ansel Adams used
>it regularly to brighten up the whites in his prints and they seem to be
>lasting rather well.
>
> CHEERS!
>
> BOB
>
Adams sometimes use the technique of an overall bleach followed by
intensification in Kodak selenium toner. This has he effect of increasing
contrast but probably also changes the curve shape of the paper a bit. The
bleach will remove veiling from highlights but will also remove some highlight
detail so it must be done with some care. I am pretty sure Adams discusses the
procedure in his book _The Print_. There are a number of kinds of bleach which
can be used on prints. The important thing is to thoroughly fix the prints
after bleaching. This is true even when using Farmer's reducer which has hypo
mixed with it. The amount of hypo in the bleach is not sufficient to remove all
the halide generated by the reducer so it is common for yellow stains to
develop later. Some photographers prefer bichromate bleach which is stronger
than Farmer's but requires clearing in sodium sulfite or bisulfite to eliminate
staining. Another bleach, but one which is used primarily for removing dark
spots, is iodine. Because iodine bleach produces silver iodide which is
difficult to fix out it is often used with a potassium cyanide fixer. This is
unnessary because an adequate job can be done with thiocarbamide or even rapid
fixer. I think plain sodium thiosulfate will work but must be given enough
time. Iodide is also sometimes used to pick up highlights.
Bleaching along with mechanical "etching" of prints was, I think, more
often used for reproduction prints than for display prints due to permanence
issues and because mechanical work is always visible no matter how carefully
done.
--
Richard Knoppow
dickburk@xxxxxxxxxxxxx
Los Angeles, CA, USA
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