U of S | Mailing List Archive | alt-photo-process-l | Re: converting anhydrous to mono...?

Re: converting anhydrous to mono...?

OK, so since most of these thread replies specify Pot Carb anhydrous...this must be the one to use (plus I can't find mono anywhere, as Richard has already stated), and that is indeed what I used.

However, I used 398g rather than the 450g the recipe called for since I made a possibly erroneous conversion from mono to anhydrous.

That being said, my final ph was 6, which is OK.

I'll just have to try it on a small 4x5 print tomorrow and see what happens. Either way, I DO know what my mixture is right now and can always adjust it later.

Also, as Loris mentioned, since many people replenish their dev through the years, it's not an exact science...(hmm, famous last words...)

Thanks to all for your help and advice...


----- Original Message ----- From: "Loris Medici" <mail@loris.medici.name>
To: <alt-photo-process-l@usask.ca>
Sent: Wednesday, May 20, 2009 1:40 PM
Subject: RE: converting anhydrous to mono...?

I'd bet it's like you said. Since I don't do develop-out pt/pd I don't
have an idea how much effect has slight changes in the developer
concentration to the development action / result... OTOH, thinking about
people using their developer *for years* only replenishing the lost volume
with fresh and filtering occasionally (not even mentioning the
accumulation of dissolved unexposed sensitizer!), it doesn't look like
something of exact science anyway...


20 Mayıs 2009, Çarşamba, 11:23 pm tarihinde, Don Bryant yazmış:

I purchase my potassium carb. from the ChemistryStore.com. It arrives as a
dry crystalline state and stays that way in the sealed bucket. Actually I
never concerned myself about the type of pot. carb. I measure out the pot.
carb. and oxalic acid and mix in a 5 gal. plastic pail. Nothing could be

I use distilled H2O. I check the pH after everything is mixed. It's a bit
work but not that bad.

Just remember Macbeth ~ " Like a hell-broth boil and bubble. Double,
toil and trouble;"

Well not so much trouble just a little work.


-----Original Message-----
From: Loris Medici [mailto:mail@loris.medici.name]
Sent: Wednesday, May 20, 2009 4:08 PM
To: alt-photo-process-l@usask.ca
Subject: RE: converting anhydrous to mono...?

Don, I haven't done it before but it seems like it's the only correct way
of doing it if you're using uncertain anhydrous potassium carbonate. OTOH,
I don't know if there's a stable crystallized version of potassium


20 Mayıs 2009, Çarşamba, 10:56 pm tarihinde, Don Bryant yazmış:
Loris and all,

I'd just add potassium carbonate to the oxalic acid solution (mixed at
right concentration beforehand) until it doesn't fizz anymore, then add
minuscule amounts of oxalic acid (patiently) checking the pH of the
solution every time, until you reach the desired pH level. (pH 6?)

That's more or less what I do. It works fine and is inexpensive.