Clearing Agents w/ Malde-Ware Pt-Pd method

PiezoDN Digital Negatives
1

Hi Walker et al.,

I was wondering whether it would be possible to combine any of the three prescribed baths when clearing the Pt-Pd print using the Malde-Ware print-out method…

For example, could the disodium EDTA and the sodium sulfite baths be combined into one?

I know it might be a little wasteful in terms of longevity (given the sodium sulfite) but it would simplify matters considerably, especially with large prints.

Best regards,

Roy

2

nope. Never combine.

The three baths are important to work in sequence.

  1. EDTA Disodium. This is a stronger acid and is the thing that does the most clearing.
    water bath
  2. Sodium metabisulfite. This is an acid (edit thanks to Keith) and clears the remainder of the iron ions. This is actually an important “clean” bath. It needs to be switched out every few prints.
    water bath
  3. EDTA Tetra Sodium. This is actually slightly higher than 7ph and it helps pull the acid out.
    water bath
    Cleaning — very important!

best,
Walker

3

Thanks for clarifying that, Walker!

4

Keep the 3 baths separate.

One correction if I may:

Sodium sulfite is not an acid — it fact with a pH of 9-10.5 according to the SDS (8.5-11.5 from PubChem) it is firmly in the alkaline range. I just checked my working solution from yesterday and found it to be closer to pH 8 after a couple of prints.

You can also use sodium bisulfite or sodium metabisulfite for the second clearing bath, both of which are acidic. Sodium bisulfite has a pH of 2.5-5.5 (10% aqueous solution) according to PubChem; sodium metabisulfite is 4.0-5.5 according to the same reference. I found sodium metabisulfite to be very unpleasant to work with due to the acrid odor.

Disodium EDTA can be hard to find from the usual sources of photographic chemicals (I get it from ArtCraft), but it can be made from the much more readily available tetrasodium EDTA and citric acid by mixing 50g tetra-EDTA and 15.5g citric acid per liter of water.

Keith

1 Like
5

Thanks Keith. Meant to say metabisulfite. It IS difficult to work with IMO (strong biting smell), but I feel like it lasts a bit longer and is better than the straight Sodium Sulfite.

Maybe @pmalde can chime in.

best,
Walker

6

All 3 have been mentioned in various iterations of the writings of Ware & Malde on the Ammonium System. In fact if you go back to the '80s when they began writing about and teaching this method of Pt/Pd printing you will find that the clearing procedure has evolved quite a bit.

I think sodium sulfite is the safest and easiest thing to use for the second bath. In a pinch one could even use Kodak Hypo Clear which is mostly sodium sulfite with a bit of bisulfite to lower the pH.

Keith

7

Hello all - sorry to be slow in responding here. Keith is correct on all counts. It is important not to mix any of these three clearing solutions, if for no other reason than the first two mixed will, as Mike Ware puts it, " tend to release sulphur dioxide gas SO2… - producing an even worse choking smell."

Sodium metabisulfite does have a longer working life, but many find the smell to be irritating. It seems to be easier to find than sodium sulfite, since it is used extensively in sterilizing cooking utensils, and in home brewing.

Sodium sulfite is easier to work with as it does not generate an irritating / smelly vapor. However, it has a very short working life. I recommend preparing it fresh, and that it be used within two to three hours, and replaced after processing the equivalent of one 8˝x10˝ point per liter. the stuff is cheap, and can be purchased from Photographer’s Formulary, B&H Photo and others.

Disodium EDTA may be prepared exactly as Keith describes above. It is also cheaply available from dietary/health supplement providers (!) like bulk supplements.com. See my list of resources for Pt/Pd printing on my web site

Intermediate fresh water rinses between each of the three baths helps
a) reduce smelly sulfur dioxide being released from carryover of EDTA disodium into bath 2, and
b) extend the life of the final, tetrasodium EDTA.

The final wash is very important, which should be between 65–75°F in gently running water for at least 30 minutes. If water conservation is important, then do six changes of fresh water for five minutes each, with gentle/occasional agitation.

Finally, I have found it easiest, when making large prints or working with delicate paper, to pour liquids in and out of a tray rather than move the print around across multiple trays.

hope this helps. Thanks.