[alt-photo] Re: casein history

[Marek Matusz]

Peter, It is definitely true that dichromates become chromates at high pH. I had an impression that chromates are more light sensitive then dichromates and that the old recipies had ammonia as one of the components to increase light sensitivity, but I could very well be mistaken. Since my casein solutions contain ammonium carbonate they do bubble happily when mixed with potassium dichromate. Marek
 > Date: Fri, 13 Jul 2012 21:25:15 -0400
> To: alt-photo-process-list at lists.altphotolist.org
> From: pfriedrichsen at sympatico.ca
> Subject: [alt-photo] Re: casein history
> 
> Marek,
> 
>  From what I understand, the dichromates shift to chromates as they 
> are made more alkaline (from your ammonia) and these salts are less 
> reactive especially in the higher pH. That may explain the lessened 
> dark reaction.
> 
> Peter Friedrichsen
> 
> 
> At 12:58 PM 13/07/2012, you wrote:
> 
> >Chris,I have not tried this approach yet, my bag of sawdust went 
> >missing. On the other hand I have been making some prints, mostly 
> >monochrome for about a year now. I have also made some prints from 
> >the one year old casein solutiojn, actually it was more then a year 
> >old. Works just fine. It is interesting that the first solution that 
> >I ever made turned to be the best recipe.Another interesting tidbit 
> >is that I have exposed and developed one day old paper checking for 
> >the signs of dark reaction and found none. There is one more piece 
> >from that batch that I will let sit for perhaps another day or two 
> >before exposing and developing. As to your other questions I read 
> >the PF article years back, but did not think of it much at the time 
> >(in terms of my own interest). I only got interested in it last year 
> >with the posts on the list.
> >
> > >
> > > Also, Marek, you were talking about Fresson maybe containing 
> > casein. The amount of casein/gelatin I have come across is 10-30% 
> > casein to gelatin. Have you tried it yet?
> > >
> > > Chris
> > >
> > > Christina Z. Anderson
> > > christinaZanderson.com
> > >
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