Flat flat flat Pt/Pd prints. Is EDTA a solution?

[sly]

I've been finding lately that I need to add alot of Na2 to my solution to get any contrast in my prints. My dmax is crappy, and I'm having a hard time figuring out why good looking negs are making such bad prints. Cot 320 used to work so nicely for me.

Took some negs specifically for high contrast (thinking carbon as a possibility as well) Overdeveloped them. Figured at least some of them should print without any Na2. Did some test strips today - looked terrific! Made 4 prints and they look as flat as undercooked pancakes. What????

What's different? Well the most obvious thing is that my test prints are done using the back of previous crappy prints. Cot 320 in all cases. The bad prints/future test strips were all put through 3 clearing baths of EDTA, and then washed (our well water is alkaline) along with the few decent prints from previous sessions.

Shoud I take all my Cot 320 and put it through EDTA and a wash before I try to make any more prints? Any other ideas from any of you bright folks who have a better grasp of the chemistry of all this than I do? Thanks

 

[DennyS]

Same batch of Cot 320?

 

[sly]

I believe so. I bought a whack of it from B&S last year when they announced they wouldn't be selling it anymore. If there was more than one batch in the order they sent, then I'm hooped.

 

[DennyS]

You might learn something from printing one of the negs on an alternative paper. I'm finding Stonehenge to be pretty consistent, I pre-treat with 3% oxalic acid for 5 min and drip dry. It's a cheap experiment, and it might give some indication if the problem is with the Cot 320. And you might like the Stonehenge...

 

[TheFlyingCamera]

First, with COT320, there is definitely an A side and a B side - you need to print on the A side (the smoother side) to get best results. Second - how old is your FeOx? I had that problem with flat, ugly prints when my Ferric Oxalate sensitizer was going bad. Third, what developer are you using? PotOx? How old is your developer? Do you filter it often enough? Why do you suspect your clearing bath? It should not have that significant an impact on the contrast, mostly on the color of the print. If your highlights were remaining yellow/orange, then I would suspect a clearing problem. For a clearing bath, I add 3 oz of PermaWash to a gallon of the EDTA solution. This helps to clear the prints very quickly and consistently.

 

[sly]

1.The test strips - that look so nice - are on the B side.
2.The FeOx was mixed in April, and has been refridgerated when not in use. Last year was the year I dealt with old FeOx, dumped it, got powder that wouldn't dissolve from a Canadian supplier, got my money back, and got good stuff from B&S.
3. Developer is ammonium citrate. I'm not sure how old it is, but it was filtered before I put it back in the bottle the last time I was printing pt/pd. I forgot that I've got a bit of Pot Ox. I've not used it, as my sources say it is less contrasty. I assumed it wouldn't solve the problem.

The test strips were done this afternoon, just before the crappy prints. I realised this problem has been going on for awhile, and was just very striking and obvious today. I've got lots of crappy prints frrom sessions this year, where the test strips had looked promising. I was thinking I was making errors - poor (too thin) application of solution, not counting the drops properly, or not crossing my fingers and whistling at the right time.

I'm thinking of the clearing bath as the big difference between pretty test strips and flat prints is that the tests, in their previous incarnation, have been through the developer, EDTA, and washing. I'm not complaining that the EDTA is not working. I'm wondering if it is doing something to the paper that makes it work better.

I'm including a side-by-side digisnap of a test strip and a nasty print. They're still wet, but cleared.

 

[eclarke]

I'd switch sides on the paper..

 

[doughowk]

The color differences between test & final would suggest different sensitizer ratios or temperatures of developer.

 

[R Shaffer]

I think you've changed the paper on your test print. You've acidified it, broken down the internal sizing somewhat and I think there is a surface sizing on side A.

I really like your test strip, lovely warmth & contrast. So you could try giving it a soak in EDTA, but that seems like a shame to pretreat a fine paper like COT.

My guess would be that your test print would allow the sensitizer to absorb more deeply and hold on to the moisture better. So short of pretreating maybe a bit of tween or humidification.