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

[Dave S]

You can also try sodium carbonate (washing soda) if you want to.


Dave  

> -----Original Message-----
> From: alt-photo-process-list-bounces at lists.altphotolist.org 
> [mailto:alt-photo-process-list-bounces at lists.altphotolist.org]
>  On Behalf Of Loris Medici
> Sent: Wednesday, January 13, 2010 2:55 PM
> To: The alternative photographic processes mailing list
> Subject: [alt-photo] Re: Chlorox Bleach Development of Gum
> 
> Just noticed: I guess sodium bicarbonate also is a household 
> item, plain simple baking soda right? ;) It's worth a try...
> 
> 2010/1/13 Loris Medici <mail at loris.medici.name>:
> > Thanks for the insight. I haven't tried any other alkaline compound 
> > with gum but I know ammonia is useful for trigger/accelerate 
> > development in casein + was once advised for stubborn gum 
> layers too, 
> > so I think you're on the right track. OTOH, bleach is easy to find 
> > (household item), plus, we don't use it that much; only about 20 - 
> > 40ml per liter. And, a final metabisulfite clearing bath will take 
> > care of the bleach remaining in the paper - if any - later...
> >
> > Regards,
> > Loris.
> >
> > 2010/1/13  <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.
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