Stain on RC papers with carbon transfer

[sanking]

I am a carbon transfer printer and often transfer the final image to a fixed out photo paper. To prepare, I fix the paper without exposure, and then wash thoroughly. I rarely have any problem with these papers but have expereinced an unexpected problem with Kodak RC papers. The problem is that the part of the paper that is in contact with the carbon tissue, after it has been sensitized with dichromate, exposed and developed in warm water has a slight pinkish-yellow look. It is not dichromate because that clears with a short soak in sodium metabisulfite. So I can only conclude that the cause is some chemical in the emulsion of the RC paper that is reacting with the dichromate in a way that does not happen at all with fiber based papers.

If anyone has any idea what may be causing this please let me know.

Sandy King

 

[Doremus Scudder]

Sandy,

Just a thought, but could it be residuals from the incorporated developer? Then again, if you are fixing and washing thoroughly, one would think that all solubles in the paper would have been washed out. Could it be that the incorporated developer is somehow not rendered soluble by the fixer and wash alone?

Or, if the paper is free of halides and other chemicals, could one of the optical brighteners be the culprit? or the gelatin itself?... Can't think of much else that would be in there.

Good luck,

Doremus Scudder
www.DoremusScudder.com

 

[Kirk Keyes]

I also wondered about incorporated developers and brighteners. How about a brief soak in a carbonate or other high pH solution and then fixing?

 

[Vaughn]

We had the same problem, Sandy, in the last workshop I gave at the university. We had some old RC paper that a student fixed out. She claimed she completely fixed and washed the paper (old graded Kodabromide RC, I believe), I was surprised at the pink color -- and also it was very difficult to develop...the gelatin did not want to melt even in the "safe" areas. She then used some of my fixed out fiber paper (everything else was the same) and had no problems.

My untested assumption was that it was something to do with incorporated developer -- but that is purely guess work on my part.

Vaughn

 

[sanking]

We had the same problem, Sandy, in the last workshop I gave at the university. We had some old RC paper that a student fixed out. She claimed she completely fixed and washed the paper (old graded Kodabromide RC, I believe), I was surprised at the pink color -- and also it was very difficult to develop...the gelatin did not want to melt even in the "safe" areas. She then used some of my fixed out fiber paper (everything else was the same) and had no problems.

My untested assumption was that it was something to do with incorporated developer -- but that is purely guess work on my part.

Vaughn

Thanks Vaughn, and Doremus and Kirk,

I definitely believe your student because there is no doubt in my mind but that I thoroughly fixed and washed the paper. What I find confusing is I never have this problem with fiber based papers, only RC, and for that matter I seem only to have had the problem with Kodak RC papers. I have used several Ilford RC papers and never seen the problem.

And whatever the reason, the cause is definitely some type of reaction with the small amount of dichromate that is left in the tissue after it is soaked briefly in water for mating with the paper support. I know this for fact because if I rub the edges of the paper with fresh water I am able to reduce the intensity of the pinkish stain a lot.

So what in the world did Kodak put in their RC papers that might cause this reaction with dichromate?

Sandy