Platinum printing question.

[sanking]

One of the main causes of staining with pt/pd is that residual ferrous iron left over from the reaction process will change to iron hydroxide in an alkaline environment, and if this happens during development it can result in staining that can be difficult or impossible to clear, regardless of the type of clearing agent. I have found that print clearing is made vastly easier if the pH of the developer is kept quite acidic, say on the order of pH 6.0 to 6.4. If this condition is met most papers should clear very quickly in mild clearing baths. Potassium oxalate and ammonium/sodium citrate developers should be slightly acidic when freshly mixed, but as you run paper through the developer there may be a gradual increase in pH. You can compensate for this increase in pH by adding a small amount of oxalic acid (for potassium oxalate) or of citric acid (for sodium citrate). You can check the pH with strips or with a small pH meter.

Sandy

[keith schreiber]

Sandy makes a good point. I think regular replenishment keeps the developer sufficiently acidic, but it is good practice to check the pH periodically, especially if you use buffered papers.

~ Keith

[lab black]

Noel,

I have found success with the three bath clearing method. In addition, especially with very large prints, I discard bath #3 every few prints, make a new bath, which then becomes bath #1, while bath #2 becomes bath #3. Cletus makes a great suggestion, which I have done for some time, in using a stir bar and magnetic stirrer to ensure that everything goes into solution. Sandy offers sage advice regarding the Ph and it is my experience that replenishing the developer every few prints has been helpful. Initially, when I started printing in Pt/Pd, I was given many different methods for clearing baths. I settled on the same formula that Keith has presented and have never had any problems with staining whatsoever. I have timers for each clearing bath as well, in addition to regular agitation. While there is quite a bit of information available regarding Pt/Pd printing, I have found Dick Arentz's book to be the gold's standard.

Best of luck

[Dennis]

When and why did everyone stop using Hydrochloric Acid for clearing baths? It is what I have used since the mid 80s and at that time was what any platinum printer used. I once gave the EDTA a try and couldn't get it to work. Now days I process my prints as I always have in Potassium Oxalate but I have taken to leaving the print in the developer much longer than I used to. At least a minute. I find that my prints clear much more quickly if I do that. I use the 3 bath method tossing the first tray at the first sign of color in the 3d tray.
Dennis

[Tri Tran]

Here's my tip. Try your Cascade dishwasher soap. Let me know how is goes. Cheers.

[Cletus]

Hmmm.....huh?....uh, well...hm. Do what again?

[keith schreiber]

Not sure but I think Tri is being ironic. But then I don't have a dishwasher so who knows!?

[sanking]

Not sure but I think Tri is being ironic. But then I don't have a dishwasher so who knows!?

It seems that Cascade makes a dishwasher solution just for platinum!

http://www.cascadeclean.com/us/casca.../platinum-pacs

And gives your prints a "fresh" or "lemon" smell.

Sandy

[keith schreiber]

Regarding HCl, for any inexperienced Pt/Pd printers considering using it, I quote from Platinum and Palladium Printing by Dick Arentz:

Hydrochloric (muriatic) acid (HCl) is mentioned in historic and contemporary literature and is still used by many as a clearing agent. It is extremely caustic. It burns skin, eyes, and clothing. When fumes are inhaled, it damages the cilia of the respiratory tract and the covering of the bronchioles in the lungs. It will also corrode the stainless steel in your darkroom. I do not use it. Nevertheless, some professional printers with considerable experience use a dilute solution of HCl as part of the clearing process with heavy, loosely woven papers. See Appendix G: Elements of Platinum Printing.

The Appendix G reference is to Stan Klimek's contribution to the 2nd edition of the book.

HCl is also not a good choice for printers who work primarily with palladium (Pd). It will bleach Pd prints if soaked for too long. This effect, however, can be used to try to salvage an overexposed print.

The use of HCl also requires a level of proper chemistry lab practice that many (if not most) printers don't adhere to. If you are going to use it, please handle it with utmost respect and care.

~ Keith

[keith schreiber]

One more thought: Someone mentioned a final wash of 30 minutes to an hour in running water. I think this is excessive, 15-20 minutes should be sufficient. For those of us who live in arid or semi-arid areas, like I do, the concurrent discussion titled Water Wise Washing is very relevant to the washing of Pt/Pd and other "alt-process" prints, as well as film and silver prints. Several cycles of fill-and-dump is probably at least as effective as a running water wash, and is much less wasteful of water.

~ Keith