Odd Stain on Print

[Scott Walker]

The following is a crop from an 8x10 contact print (please excuse the dust and crappy scan). I was determining how long to tone in "Kodak Professional Rapid Selenium Toner" for desired effect. I took 5 identical prints and toned for 1 minute to 5 minutes at 1 minute increments. Toner was diluted 1:5 with constant very light agitation. The prints were pre washed for 1 hour, toned, then washed again for 1 hour. I did not use a hypo clearing agent.

The first crop is from the print toned for 1 minute and there is no sign of any staining



This second one is from the print that was toned for 2 minutes. The red lines point to a change in image tone or contrast.


This strange tonal change was evident in the prints toned at 2 minutes, 3 minutes, and 5 minutes but not at 1 or 4 minutes. The problem was in almost the same spot on the 3 prints but not exactly. I know for sure that the 5 sheets of paper were pulled out of the package in sequence but once they were printed and washed I have no idea if they stayed in order and really doubt if they did. The paper is Ilford MGFB 11x14 and purchased new within the past month. Prints were developed in Dektol (brand new batch) stopped in used Kodak stop and fixed in fresh Kodak fix.

Contact printed using a sheet of standard framing glass. Light source was an enlarger using a cold light head and projected through an Ilford multi-grade #2.5 filter.

I am pretty sure this was not here before the toner, at least it was not evident enough to be noticed and I squeegeed the prints and dried them for about an hour and inspected them very closely before washing again and toning. The initial wash was only about 20 minutes and the wash before toning was 1 hour.

Any thoughts?

[Gem Singer]

A few thoughts:

KRST is usually used at a dilution of 1:20. A dilution of 1:5 seems kind of strong.

KRST contains rapid fixer. Good idea to neutralize it with HCA when using fiber based papers.

No need to wash for an hour before toning. If starting with prints that have been washed and dried, merely re-wet them in a tray of water or give them a short wash before toning.

Wash longer after toning.

Looking closely under magnification, looks like the defect is in the negative. It has a circular pattern. Possibly due to uneven development. Toning made it more noticeable in the print.

[Scott Walker]

Thanks Gem

I normally use a 1:20 mix but I have used it as strong as 1:2 in the past without having this happen and I have even used it in a turky baster @ 1:5 to selectively tone areas.

I am pretty sure it is not on the negative, if it was it would not shift and it would likely get more evident with more toning and the print that was toned for 4 minutes did not have the problem.

It really has me baffled I think I will try fogging, developing, and toning a sheet of paper to eliminate the possibility that it is a paper issue.

[Brian Ellis]

I don't think it would necessarily get more evident with longer toning times. There's a point in the selenium toning process at which dMax reaches it's maximum. If you tone longer you actually decrease dMax.Years ago Fred Newman published the results of his extensive selenium toning tests in the newsletter that The View Camera Store published. Those tests, made with different dilutions and different papers and times, demonstrated this somewhat counter-intuitive phenomenon.

[nolindan]

The mark is similar to ones I have found on my prints. In my case it is a result of 'puddling' of the developer when the print was inserted in the tray. If the prints are inserted in the same way then puddling in the same pattern might be expected.

Selenium does all sorts of funny things - that it makes these marks more evident wouldn't surprise me.

[Doremus Scudder]

I vote against selenium toning being the culprit, although the toning may make the defect more apparent.

It's hard to see from the posted images if there is a different tone change in the affected area. If so, then a paper coating issue may be the culprit. I'd go ahead and try the fog, develop, and tone a sheet of paper or so to see what's up.

If the area is markedly denser, then the "puddling" phenomenon Nicholas mentions may well be the culprit. I would think, however, that the developer would have to sit and work in the puddle for a relatively long time before the rest of the surrounding area was immersed in order to make such a change. Plus, the developing time would have to be rather short. How do you immerse your prints in the developer?

The definite edge and rather roundish perimeter of the spot in question also makes me think of imperfections in your cover glass. Do you always use the glass in the same orientation and with the same side up? If not, maybe you are getting a defect from some unwanted refraction in the glass you are using. Another possibility is that the contact between cover glass and print is not always ideal. Maybe it's an air bubble between glass and print surface? This would, of course, change refractive index for that small area.

I kind of like that last idea...

Good luck finding the problem,

Doremus Scudder
www.DoremusScudder.com

[Greg Blank]

You should never have this problem again if you go right from a few minute final fixing bath to a HCA+Toner combination. Use the long wash only after toning.

[IanG]

The staining is due to the original fixing steps, it's residual silver-thiosulphate complexes that haven't been washed out properly. They are barely soluble and the safest way to prevent these issues is two bath fixing.

Ian

[Scott Walker]

Turned out to be a cover glass issue, something I had no idea was even possible. After determining that the paper was not the problem I thought the most likely source had to be between the light source and the cover glass. So I cleaned the cover glass again and accidenticaly discovered a strange defect in the glass that could only be seen when looking through the glass at a certain angle. It looked like a very faint curved crack. So I fogged a few more sheets, this time through the cover glass and sure enough I was able to create the spot with lower density, but not on every test The cover glass is in the garbage in a few hundred pieces so I can't accadentialy do this over again a few years from now.

Problem solved