[alt-photo] Chlorox Bleach Development of Gum

[C.Breukel at lumc.nl]

And another one, which Loris already kindly answered, but might be
interesting to draw attention to below method again anyway..


Cor



.....................

Last night I played a bit with gum over platinum, I made an exposure
mistake, and seriously over exposed a cobalt blue gum layer. After a
night long soak/development I saw barely some development this morning.

Than I recalled below method as originated from Marek and described by
Loris.

I was wondering about one thing: when you do the bleach step, do you
keep the gum layer towards the solution, just like a "normal" water
developing step, or do you place it image side up and gently rock the
tray.

I assume the first?

Thanks & best,

Cor

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RE: Miracle size for gum (chlorox bleach development)

From: Marek Matusz <marekmatusz at hotmail.com>
To: alt-photo-process-l at usask.ca
Date: 14 Oct 2009 - 3:30p.m.

Loris,
A very good description and a starting point for experimentation. I
usually keep my bleach concentration on the low side (20cc/liter), but I
actually no longer measure the exact amount. Just like a cook adding
salt to the dish without measuring how much, I just pour some bleach
into the tray. Interesting part of the process is that I had some test
strips that I ried to develop overnight and there were still not quite
there yet after 12 hours. A 30 second bleach soak followed by 10 minute
water development made just perfect test strips.
Marek
 

  _____  

Date: Tue, 13 Oct 2009 17:12:29 +0300
From: mail at loris.medici.name
Subject: RE: Miracle size for gum
To: alt-photo-process-l at usask.ca


Bleach development, in short, is developing by adding small amnt.
(20-40ml into 1000ml) of household bleach into the development water. It
was brought into attention by Marek Matusz a couple of years ago. See my
procedure below, I'm sure Marek will describe his and/or add more
information later:
 
* Prepare two development trays, one with bleach and one without.
* Use a generously pigmented coating solution; a pigment amnt. that you
would not normally use.
* Expose longer; I use 2x-3x-4x times the normal. (Test!)
* Put the print in the plain water bath to let the unreacted dichromate
ooze out, refresh the water few times and drain until the print is clear
of dichromate. There will be no (or almost none) development action.
Refresh the water again.
* Put the print into the bleach bath and wait for a pre-determined time
such as 1-2 minutes. (Test!) The print will start to develop.
* Drain and put the print in the plain water bath, the bleaching action
will continue for some time. Check 5-10 minutes later, if the
development speed/amount is consistent with the norm (I mean what you
experience with normal prints after 10 minutes of development), change
the water and continue to develop in plain water. Or, put the print
again in the bleach batch to further trigger/speed up development, but
keep the bleaching time short this time (15-30 secs), once triggered the
development is very quick in the bleach bath.
* Put the print in the plain water bath and continue by bringing back
the print to the bleach bath if further more is necessary. You got the
idea!
 
You can use this method to save overexposed layers too - works most of
the time. It's my most useful tool in workshop situations, saves time
and motivation! :)
 
Using this method, you can print very dark one-coat prints which have
convincing blacks. In other words: "subtlety and drama at the same
time"... (See Marek's recent step tablet tests.)
 
As I said before, I'm sure Marek will add to the information above (or
correct it).
 
Hope this helps,
Loris.