What causes stubborn clearing in PtPd?

Every once in a while, like this evening, I wind up working on a PtPd print that is just stubborn about clearing.

Tonight I tried everything I had in the house: EDTA and Sodium Sulfite; Citric Acid; Oxalic Acid; HCA 1:4, 1:2 and 1:1. This print would not clear. If I had had some muriatic, I would have tried that, but didn't have any. All the earlier prints this evening were clear in seconds in the first bath.

What contributes to tough clearing? Paper too dry at exposure? Long exposures? Too much heat in drying? What experiences have you had?

Neal

Neal, Although i have very little experience so far (Working on changing that)
Are you using any Oxalic Acid in your Ferric oxalate?
When i mixed my Ferric oxalate i used Dick Arentz mix on page 32 in the second edition. 15g ferric Ox, 1g Ox Acid and 55ml water.
I have not had any clearing problems even in a pretty alcaline first clearing bath of EDTA and Sodium Sulfite (Did not have test strips when i started) Thanks to Clay i now keep it at about 6.5 Prints cleared in less than minute.



jan

Hi Jan
I use a little EDTA when I mix my Ferric per the B&S instructions. I will re-read page 32 and try the Oxalic to see if that helps.
Thanks,
Neal

Hi Neal,
Try this. Lime away household product. 1 part lime away/ 8 part of water. TT

Neal,

I use 2g of ox and .75g EDTA in my FO. The rest of the formula is the same.

The OX will change the speed of the FO considerably, so you will need to re calibrate your speed point after making a change like that.

Other than that, you know about keeping the developer in the acid realm. If the developer is even slightly basic, it will make the FO much less soluble.

Lime Away is mostly an acid (phosporic, I think). Probably wont do much for you if you tried oxalic.


---Michael

Thanks Michael,
My developer is at 5.0 at the moment.
The Ox will make the sensitizer slower?
Thanks,
Neal

Neal,

Faster...

You could have gotten a sheet of paper that was especially tough due to internal chemistry. I think that happens a lot more than we know. At least that's what I blame all my problems on...

One thing, it's possible the problem is related to how you dried the paper. Some papers are a real problem in that you have to be very consistent and somewhat aggressive about getting the coating on there, and then letting it sit a while, and then drying the coating before it soaks in too much.

---Michael

Okay, for those following this, here are the steps I've taken on this issue:

I mixed up fresh FO #1, this time with MM's recipe of 2g ox and .75 EDTA (tetra).

My first clearing bath is now Oxallic Acid (I had tried Citric but didn't get much action so, mixed up some Ox Acid). Second is Citric. Third is EDTA (di) and Sodium Sulfite.

Paper is Stonehenge that until recently hasn't given any trouble.

I didn't use water rinse between developer (5 minutes in 100 degree PotOx), but rather went straight into first clear.

Results: I still get a very stubborn tone in the theoretically unexposed area. Interestingly, the tone doesn't appear in the highlights or the high values of the Stouffer wedge, just in the areas that are 'masked' during exposure with RubyLith. Could the RubyLith be allowing some exposure? And, therefore could what I be seeing actually be exposure? By the time I get into the second clearing bath this 'tone' doesn't really have much yellow color, maybe no more than the color of the Palladium. Is RubyLith totally opaque to UV? This tone eventually goes away, but maybe this is actually fading in prolonged clearing bath?
Thanks for any thoughts. I think I'll have to try some other paper.
Neal

Neal,

How log are your exposures? I have on occasion seen rublith print through when the exposures are long.

However, even the print through is not yellow looking, it's the tone of a zone IX or slightly lighter image tone. If it looks yellow, then it is an issue with the clearing for some reason.

Try a a test... do an exposure with absolutely opaque cardboard over top of a portion of rubylith and a piece of the negative and an area of uncovered coating, and then develop to see if you are getting some print through. Use a similar exposure as has been giving you problems. If you can see a difference between the cardboard/rubylith area and the rubylith-only area, then you have your answer.

FYI, that's part of the reason I generally use goldenrod instead of rubylith. I think it is more UV opaque. There's other reasons, but that is a primary one.


--Michael