RE: Homemade Potassium Oxalate

All right Nick! That is pretty it. Don depending on the quality of the
ingredients, you may see black specks floating in you finished solution.
Filter those out before use. If you can find a local chemical supplier (
thanks to Dan B I have one just a couple miles away) it drastically reduces
the cost of Pot Ox if you brew it yourself. So cheap in fact, that having
several flavors (warm, cold, + X steps a la dilutions of dichromate) around
is easily done if you have storage space.

Eric Neilsen Photography
4101 Commerce Street
Suite 9
Dallas, TX 75226
http://e.neilsen.home.att.net
http://ericneilsenphotography.com
 
> -----Original Message-----
> From: Nick Makris [mailto:nick@mcn.org]
> Sent: Friday, March 04, 2005 10:05 AM
> To: alt-photo-process-l@sask.usask.ca
> Subject: Re: Homemade Potassium Oxalate
>
> Don, here is Eric Neilson's note to me of sometime back, along with my
> method which was at least in part derived from Eric's and other methods.
> Same goes for the Cold Bath developer. Can't be absolutely sure that I
> updated the doc the last time out, but one thing I can tell you is that it
> gets quite active for a while, so use extra large containers and make the
> prep outside or in a very well ventilated room with a large sink.
>
> n
>
> Preparation of Potassium Oxalate
>
>
>
> Eric Neilsen wrote:
>
>
>
> I use 2 lbs of Potassium Carbonate (mono) and 1.75 lbs Oxalic Acid. First
> dissolve the potassium carbonate in about 2 1/2 quarts ( 2500ml) of
> water.
> I use distilled or similar quality water to help keep the product as clean
> as possible. Then slowly add the oxalic acid with stirring. It will
> bubble
> quite energetically, as it gives of CO2 and heat. You may consider doing
> this outside, but a good lab should handle it just fine. When you have
> added enough oxalic acid, the bubbling will stop. Top off to make 1 gal.
> I
> usually add an extra 150 gm to the fresh batch to keep it on the acid
> side.
>
>
>
> Nick Makris wrote:
>
>
>
> To make Potassium Oxalate developer for PD/PD prepare as follows:
>
>
>
> Might be better to do this outside or at least with good ventilation as
> the
> process gives off CO2, some heat and a significant amount of bubbles.
>
>
>
> To make 1
> Gallon 2 Qt 1Qt
>
>
>
> Start with distilled water (ml) 2200
> 1100 550
>
> Add grams of Pot. Carbonate mono 907
> 454
> 227
>
> with stirring until dissolved.
>
> Measure Oxalic Acid (gm) 794
> 397 199
>
> Slowly add small amounts of
>
> the above measured Oxalic Acid with stirring,
>
> waiting each time you add until bubbling
>
> stops - continue until all of the above measured
>
> amount has been added - produces balanced ph of 7.0.
>
> Then add more Oxalic Acid to 60
> 30 15
>
> keep solution on the acid side.
>
> Remember, add slowly - produces 5.1 ph.
>
>
>
> Top off with distilled water to make desired quantity.
>
>
>
> On 11/2/01 I prepared a fresh batch of Cold Bath Developer; the old
> developer had a PH of 5.9 and the new batch was 5.0. The discernable
> difference was add contrast - ie, less density in the highlights and more
> density in the shadows and it may have been slower to react???
>
>
>
>
>
> C:\foto\documents\Potassium Oxalate Prep.doc
>
>
>
>
>
> PT/PD Cold Bath Developer
>
>
>
> 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
>
>
>
> Eric Neilsen wrote:
>
> It has several different formulas but the essence is that about 180g
> Potassium oxalate with 50 to 60 grams Potassium Phosphate mono basic. You
> should be able to dilute the Pot. Ox. solution 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
> (as prepared above). This explains the need to dilute it in order to add
> something else to the solution.
>
>
>
> Therefore, to make a quart of Cold bath developer from prepared/saturated
> Pot. Ox. solution: start with 20oz of the above and add 12oz (60%
> dilution)of distilled water. Slowly add 50-60gm of Potassium Phosphate
> Mono
> basic, continue to stir until completely disolved. If there is any
> undisolved residue, add just a little distilled water, stir and allow to
> stand and repeat if necessary. Adjust this instruction as required.
>
> The use of this may be required in order to render the desired,
> appropriate,
> or required color of the final images. This is the last step after
> determining how much PT vs PD, and the temperature of the developer. The
> PT
> will cool off the PD and the Pot Ox will warm up the PD.
>
>
>
Received on Fri Mar 4 10:16:31 2005