From: Peter Fredrik (pete@fotem.demon.co.uk)
Date: 03/28/01-07:07:37 PM Z
Judy Seigel wrote:
> On Tue, 27 Mar 2001, Peter Fredrik wrote:
> > > FULLY OXIDIZED..... IF WHATEVER TINGE OF ORANGE REMAINS DOESN'T BOTHER
> > > YOU AESTHETICALLY (and I rather like it), IT WON'T BOTHER ANYTHING ELSE.*
> >
> > What's all the shouting about ?
>
> Actually Pete, I'm using a keyboard with a caps lock just under my pinky
> and it's always going off... usually i go back & retype but this time I
> thought what the hey -- because some things seem to go against a gradient:
> and I've never seen a book or article in OUR time that didn't end with
> that ritual. (I don't seem to get visible stain myself, maybe my one sign
> of grace from on high -- maybe also because my soaks are usually long.)
> Anyway, apologies to all for "shouting" (it's been a shoutable week,
> though).
I understand girl I get weeks just like that !
>
>
>
>
> Why the sulfuric,
> which I prefer not to handle (tho I have, I will, I can), instead of
> relatively benign sodium sulfite, or even k bisulfate... A half teaspoon,
> no pouring of strong stuff ????
So do I
.
Okay let me try to explain .
I have been for years concerned with trying to obtain maximum colour saturation
in photo-alt at the same time as achieving creative flexibility.
When I first started the brown stain proved a problem degrading the cyan to a
muddy grey knocking the edge of the magenta and affecting the yellow only to a
slight extent .
This problem was quickly solved by using any of the following clearing procedure's
5% sol bath of either
sodium sulphite , sod/pot metabisulphite, pot alum, liquid acid hardener, or a
long soak wash in running water 12 hrs /24 hrs, all of these baths gave much
cleaner colour the most noticeable was the effect on the cyan which went from a
muddy grey to a fully saturated blue, so far so good.
However I noticed as time went there seemed to a slight green cast appearing which
was a will of the wisp effect hard to predict .At first I thought it was badly
mixed pigment . I was using acrylic colour so I did a series of tests without any
colloid present and mixed them physically with a paint brush ,the result no green
caste. So it had to be the colloid /bichro mix .Working on this surmise I did a
further series of tests with out pigment the results of which were most
interesting .With a full exposure the colloid went brown using different papers
the shade of brown was different, I also used three different colloid to cross
check on a control sheet of fabriano artistico
1) W&New gum , 2) egg,, 3) gloy gave the following results --: 1) strong
brown 2) green brown 3) medium brown
These tests were then subjected to the clearing baths and as expected they each
turned a soft green grey .The colour of turquoise that has been let down with a
slight grey tone. So how could I get rid of this residual stain a number of other
chemicals were tried with no effect.
Then I remembered work I had done on bromoil year's before many bromoil bleaches
contain a small amount of sulphuric acid, which had the effect of turning the
gelatine colourless before inking, and as similar chemistry is employed I decided
to give it a try.
BINGO it worked the brown stain disappeared and no green stain reappeared, however
the stain did not in fact go away on heavy exposure a light neutral grey tone was
created, but this did not pose any problems as it just made the colours in the
shadow regions slightly darker and in effect undetectable, in normal practise.
So there we are,
All my best,
Pete.
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