I'd like to jump in here with thoughts about the varying results people seem to be getting with this paper.
First, the pH of a good platinum/palladium paper ideally should be either neutral or slightly acidic because the platinum and palladium chemistry itself is acidic. All the experienced printers on this thread can probably share tales of soaking 'archivally buffered' papers in trays of oxalic acid to neutralize the buffers and make it suitable for the process.
In that regard, I wonder if the differences people seem to be experiencing with this paper could possibly be to slight variations in the ferric oxalate chemistry being used? I know that Kerik and I both use a formula for the ferric oxalate sensitizer that is basically 27g ferric, 4g of oxalic acid and 2g of EDTA in 100ml of water. The oxalic acid makes the sensitizer slightly faster, and I wonder if in this case, it might also be serving to sort of acidify-as-you-coat the paper.
Another variable could be the post development wash water. I know Kerik enjoys nice neutral tap water at his place in California. When I lived in Houston, the water had a pH of 8-8.5! I learned the hard way that dumping a freshly developed print in a tray of plain tap water was a recipe for getting anemic blacks in my prints, not to mention making it virtually impossible to clear properly. I always make sure that my prints never touch anything with an alkaline pH until they are fully cleared.
After pondering the results of almost 2 dozen test prints, and the comments from others here, it occurred to me yesterday that one variable no one has mentioned, and one which is easily overlooked, is developer pH. After doing a couple more tests yesterday, new sheet, with and without Tween, results similar to my earlier tests, I thought to check the pH of my developer, since this paper is alkaline according to my pH pen, and found it to be between 7 & 8 or slightly alkaline. (I only have full scale 1-14 litmus paper on hand, so not very precise.) After adjusting the pH of the developer down to ~ 6.5 by adding about a tablespoon of oxalic acid to the 3L bottle of potassium oxalate, I finally was able to make an acceptable test print. Smooth coating, no mottling, good gradation, Dmax ~ 1.4, no clearing problems.
Of course this has no bearing on the coating problems that Dave and I, and maybe others, have been experiencing. Yesterday I did not have that particular problem, but I don't know why. It was a different sheet of paper. The results were much improved by lowering the developer pH, but none of yesterday's tests had the mottling problem that I was having previously.
My FO formula is the same as that used by Kerik and Clay.
What I have learned so far (I think):
- do use Tween
- do not acidify paper
- do not humidify paper
- ambient humidity should be < 50%
- maintain developer pH below 7
~ Keith
To clarify whether the tween is causing my problem can someone who was getting normal results with 2 drops of tween per 10x8, add maybe one or two drops more and see whether these spots/clumps start to appear once they have laid down a coat. This would then confirm that the tween is the problem and needs to be used as little as possible.
(Edit, I have attached another example of the problem without light shining through it, this is with two drops of tween per 10x8, the clumps are light brown in colour)
I have been adding 1 drop of tween for a 5X7 negative and have not seen any spots. I have printed 6 or so images on the paper, all were spot free. My process has been...
F/O 10 drops, Palladium 9 drops, Na2 1 drop, tween 1 drop. I coat with a brush and let air dry in the dark for 20 min. before exposure.
Has anyone else seen the spots or is Davec the only one?
Matt
Next time can you try adding an extra 1 or 2 drops of tween to see if you can force the effect to happen.
Dave, have you tried to coat the paper with distilled water first, wait until it's surface dry (I mean until no surface sheen can be seen when inspected in oblique light...), and then do the actual sensitizer coating? Maybe that could give you good absorption w/o using any wetting agent. (Yes, I know it sounds too cumbersome, but worth to try IMHO...)
Regards,
Loris.
So I did a test tonight with varying amounts of Tween. I would have to agree with Davec that the tween looks like it is causing the spots. I did my standard mix for a 5X7 negative and only varied the amount of tween. I also coated a piece of Revere Platinum with just tween. The paper appeared to blister randomly where the tween was brushed on. The blisters did go down after about 1/2 hour.
My conditions tonight were 45% humidity and 75 degrees. Each square was coated with a brush. The mix is 10 drops F/O, 9 drops PD, 1 drop Na2, and the last drop in the count is the tween. As you can see as the tween increased so did the brown spots. I was not having this problem before and I took this sheet from the bottom of my pile.
Matt
Matt,
So far, all of my tests without Tween have produced slightly anemic speckled blacks that seem to be common with alkaline papers. I get a similar result with BFK, for example. Acidification usually solves that problem. With some papers Tween solves that problem too, but it does appear to be causing this new problem on Revere. I typically use 1 drop of Tween per 1.5 - 2 ml of coating solution with most papers. I would guess that your 10+9+1 coating mix is ~ 1ml or maybe a bit less, so even 1 drop is a higher proportion than my standard. However, with the Revere tests I have been using a mix of .5ml FO + .5ml Pd + 1 drop Tween. (No Na2.) Tomorrow, or more likely Wednesday, I will try again diluting the Tween (or mixing 2ml) so that it is consistent with my usual practice. Maybe we are just using too much of the stuff.
~ Keith
Hi Loris, I am not adverse to trying other techniques to make papers work if they are worth it, Fabriano Artistico is one. Absorbtion maybe a problem however now that i have identified the problem is occuring to a lesser extent without tween absorbtion is not my main issue now, I would like to understand what sort of sizing the paper has and whether this is the problem effecting my batch.
Francesco, what type of sizing is used in making Revere?
Matt,
Have you printed them yet? Are you getting a smooth rich black in the samples without Tween?
So far, all of my tests without Tween have produced slightly anemic speckled blacks that seem to be common with alkaline papers. I get a similar result with BFK, for example. Acidification usually solves that problem. With some papers Tween solves that problem too, but it does appear to be causing this new problem on Revere. I typically use 1 drop of Tween per 1.5 - 2 ml of coating solution with most papers. I would guess that your 10+9+1 coating mix is ~ 1ml or maybe a bit less, so even 1 drop is a higher proportion than my standard. However, with the Revere tests I have been using a mix of .5ml FO + .5ml Pd + 1 drop Tween. (No Na2.) Tomorrow, or more likely Wednesday, I will try again diluting the Tween (or mixing 2ml) so that it is consistent with my usual practice. Maybe we are just using too much of the stuff.
~ Keith
... Stan Klimek suggested using 5 drops of distilled water per 10x8 instead of tween, i will give that a go, however i believe the underlying issue is with the paper.
Just a minute here gentlemen. Isn't this paper called Revere Platinum? Is it or is it not being marketed as a paper specifically tailored to the needs of the Platinum printer? Why is it gelatin coated? Why is it alkali? Why all this hoop jumping?
David
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