[alt-photo] Re: Chlorox Bleach Development of Gum

[pfriedrichsen at sympatico.ca]

Has anyone tried using an alkaline bath instead of the bleach?.

I haven't tried the bleach development but I have been working with 
"gum" subing gelatine, or casein, and the print clears more readily as the
developer is made more alkaline. Salts I use are Sodium Bicarbonate 
for a mild alkaline  solution pH of about 8, or Sodium Carbonate with 
a solution pH of around 10.

A dilute bleach solution that I made up using about 200 ml water to 
20 ml household bleach gave me a pH of 11.2. This is very alkaline. 
 From what I understand, an alkaline pH changes the charge of 
particles and cellulose, so they start to repel each other hence the 
alkalinity of most detergents.

This would be good because it would avoid the use of hypochlorite 
which is hard on cellulose fibers. This is just a hunch.

At 08:21 AM 01/13/2010, you wrote:
>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
>
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>
>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.
>
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