Couple o platinum questions

Straight Palladium will give you a much warmer tone than any pt/pd mix. For my own use, I prefer the Potassium Oxalate developer, which does shift image tone when heated, but it is not as dramatic a shift as excluding platinum from the emulsion.

 

Metal content, developer (and temp of the dev), and paper all come into play in the final print color.

Van Dyke is a silver process...brushed on the paper in the same manner as Pt/pd printing. They can be toned with platinum to give a look that is much like platinum/palladium prints.

Vaughn

 

Also in my experience with Potassium Oxalate the age of the developer affects color.
With a brand new batch of developer heated and using Palladium I get pretty warm prints. After a couple years seasoning with Pt/Pd mixtures it won't change color much regardless of temp.
Dennis

 

I have found potassium Oxalate to be much warmer than the other developers, especially when heated. I heat to 125, or "low" on my walmart hot plate.

 

Dennis, with old well-used developer, does the development temp still affect the "speed" of the paper (ie, increase temp -- decrease exposure time under the UV) ?

Vaughn

 

If it does it isn't much. Occasionally I will forget to put the developer back into the heater and it gets cool in the tray and I process anyway and it doesn't seem to make any difference. I think my heating the developer becomes part superstition after awhile. My developer gets really old because when I heat it I am usually careful to pour it right back in the bottle and cap it so it doesn't evaporate between prints. Then when my volume starts to get low I add fresh developer to the old.

 

Here's a formula for a developer that gives warm tones at room temperature:

180g Potassium Oxalate
60g Potassium Phosphate monobasic
1000ml Water

From Ted Rice's book "Palladium Printing Made Easy".

 

Actually you don't tape. You mask with Rubylith (graphic arts film) during exposure. Rubylith completely blocks UV transmission. Then the area outside the borders of the negative is never exposed, so it disappears in the clearing bath.

 

While rubylith is an option, you can absolutely use tape to create straight borders. I've done it this way for years. Look for 3M/Scotch safe-release masking tape for delicate surfaces. The current product is blue. There is an older version that was white that I like a little better (still have a stash), but the blue stuff works. Look for the lowest tack you can find. This will work very well on smooth papers like Platine, Fabriano Artistico HP, COT 320, etc. It's a little dicey on a textured paper like Rives BFK because it will pull up fibers if you press it down too hard. The white tape was the best for textured papers. I think there is a newer version of the white tape, but I can't find it with a quick Googling.

 

I switched from Ammonium Citrate to Potassium Oxalate a while back, much prefer the warmer tones PO has even at room temperature on Platine, also the dichromate method has been much more consistent compared to the ratio method which obviously uses AC. If you do heat AC make sure not to go over 120 F, last time i did that i had some strange results. In Dick Arentz's book on platinum printing there is a table on page 96 regarding heating AC and PO, you might want to take a look at.

I saw an exhibition a couple of years back in Stroud where there were a good number of 31 Studio's prints show, they were outstanding, it was great to see so many well known prints in one room. Paul and Max Caffell are execptional platinum printers and have printed for many great photographers, hope they have another exhibition sometime.

 

I could easily be wrong with this, but would not hot Potassium oxalate developer just (or mostly) give off water vapor when it evaporates, thus get stronger over time. If that is the case then one would just add some distilled water to "replenish" one's developer.

I'd like to know, because it is about time for me to bring my Potassium oxalate back up to its original volume after a long printing session through this past night and into this morning's light.

Vaughn

 

My developer develops grit like black pepper and also green crystals. I decant the developer off the grit sometimes and add a little water to dissolve the crystals. I am not very scientific about it but doesn't seem to be very problematic. I also sometimes add a little Oxalic Acid to the PO because I read you are supposed to do that to keep the developer acidic. I can't verify that ever had any affect on anything.
Dennis

 

JArvman...what was it about his coating techniques that did it for you? In what way was it different? What papers was he using and did they humidify, acidify, etc...?

Tell us everything! ;-)

Thanks...Paul

 

Kerik...I find that the blue tape transmits UV when printing in the sun...

 

Ummm... you missed the point. Maybe I wasn't clear. You apply the tape prior to coating the paper then remove it after drying. The idea is to mask off the area to be coated, not masking over the coated area. That's what Rubylith, Amberlith or Goldenrod are for.

 

Vaughn you are correct. Heating the developer releases water vapor resulting in an increased concentration. The crystals indicate the solution is beyond saturation at room temp. You can either add water (distilled or deionized) until they dissolve or simply filter them out then add fresh developer which is what I usually do. The actual concetration of the developer is not that critical. It is a good idea to filter out the black grit fairly regularly because it can sometimes stain the paper.

You should also monitor the pH of your PO with litmus paper (a pH meter is more accuracy than you need, and they break too easily). I like to keep my PO around pH 6 by adding small amounts of oxalic acid. Once the developer becomes alkaline (pH 7 or more) it can have a detrimental effect on the print quality. You can also do as Dennis suggests and sprinkle in some oxalic acid once in a while and not worry about the litmus paper.

It ain't rocket science, so don't worry about being too anal about this stuff. Some basic maintenance will keep your developer going for a long, long time.

 

Jarvman it's easy to make your own PO from potassium carbonate and oxalic acid if you can get those chemicals locally.

(You may want to do this outside or at least with good ventilation as the process gives off CO2, some heat and a significant amount of bubbles. Think gradeschool volcano project.)

To make 2 Liters:

1. Start with about 1100 ml cold distilled water in a container big enough to handle all the effervesence - maybe a gallon or two.

2. Add 450 grams of Potassium Carbonate mono with stirring until dissolved.

3. SLOWLY add 400 gm of oxalic acid to the potassium carbonate solution with stirring, waiting each time you add the acid until the bubbling subsides. Continue until all of the oxalic acid has been added.

4. Add water to bring total volume to 2 liters. Check the pH at this point. It should be near 7.0 (neutral). Now add more oxalic acid in small amounts and keep checking the pH. When you get the pH to about 6.0, you’re done.

 

Is the advantage to this in the cost? Or just easier than having it shipped?
Dennis

 

If you buy the chems in reasonable quantity it's much cheaper this way.