[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: Cold Bath Developer - PT/PD

Eric,

Many thanks for your prompt reply - I barely received the original message
and yours came in quickly thereafter.


Nick

----- Original Message -----
From: Eric Neilsen <e.neilsen@worldnet.att.net>
To: <alt-photo-process-l@skyway.usask.ca>
Sent: Saturday, July 01, 2000 3:02 PM
Subject: Re: Cold Bath Developer - PT/PD


> NIck, The cold bath developer is listed in a number of text.  I have it
> within the pages of a Kodak Guide to Practical Photography printed by in
> 1978.  It has several different formulas but the essence is that about
180g
> Potassium oxalate with 50 to 60 grams Potassium Phosphate mono basic.  The
> powder potassium oxalate is sold by B&S, the Formulary, Artcraft, etc.. It
is
> very expensive compared to making it yourself with potassium carbonate and
> oxalic acid which could be a very good reason Dick left it out of his book
on
> platinum printing. :)?
>
> You should be able to dilute what you have made just short of 1:1 with
water
> and add the potassium phosphate mono basic.  The Formulary also sells the
> potassium phosphate mono basic.  It may give you a bit more contrast than
the
> standard PotOx developer.   You can dilute your standard Pot Ox with water
> and it will give you a print that is slower, and with more contrast but it
> will have more grain or at least that is what I saw with those combination
of
> processing elements.
>
> the potassium oxalate developer that you have made is close to saturation.
> This could explain the need to dilute it in order to add something else to
> the solution.
>
> Hope this helps
>
> EJ Neilsen
>
>
>
> Nick Makris wrote:
>
> > I have run across a formula for PT/PD Cold Bath Developer which is as
> > follows:
> >
> >         175 gm Pot Oxalate, 75 gm Pot mono Phosphate and 1 qt. H2O
> >
> > The implication here is that Pot Oxalate can also be a dry powder (it
was
> > probably first a dry powder).  However, I only know Pot Oxalate as a
> > solution prepared from Pot Carbonate and Oxalic Acid.
> >
> > The question is, how would one go about modifying the above formula to
> > prepare a qt. of Cold Bath Developer if you were to start with a quart
of
> > Pot Oxalate in solution form, or could you???
> >
> > Seems like one would just add the Phosphate - but as we all know it's
> > usually not that simple.
> >
> > Many thanks,
> >
> > Nick
>
> --
> Eric J. Neilsen
> 4101 Commerce Street, Suite #9
> Dallas, TX 75226
> 214-827-8301
> http://e.neilsen.home.att.net
> http://www.ericneilsenphotography.com
>
>
>