Old Agfa 10E56 plates

[lobaz]

Hi,
we have a full fridge of very old Agfa plates (10E56 + antihalation, 10E75, 8E75) - I think they expired about 20 years ago. Anyway, the red ones work great. On the other hand, when I try a green one, the emulsion gets milky and no image appears (maybe once I got a very very weak one). Does anyone have any idea what happened? If I had just green ones, I would say they are gone, but I am wondering that the red ones have no such problem.

Petr

[Dinesh]

Perhaps the dye has faded by some dark reaction mechanism? Can you add a green dye to the green film and revitalize it?

[142laser]

We had good luck with well expired red plates here at USF also but we never did any green ones. The main problem here is relative humidity when taking then out of the refrigerator...must warm up in dry air; I am in Tampa Floroda...humid.

[lobaz]

Can you add a green dye to the green film and revitalize it?

I have no idea, I never tried to play with the emulsion. Although I don't understand emulsion chemistry, I do not think that just adding the dye would help as the emulsion gets as white as milk-in-water after development; I would expect that pure loss of sensitivity should lead to clear emulsion and no image after development. Anyway, can I use the procedure from Saxby's Practical Holography (p. 477)?

prepare mixture of:
100 cm3 of 3% solution of LiBr in 2:3 water/methanol mixture
2.5 cm3 of 0.2% solution of 1,1-diethyl-2,2-cyanine iodide in methanol
0.5 cm3 of 1% ascorbic acid solution in water

then soak the plate in the mixture for 1-2 minutes,
rinse the plate

[Jeffrey Weil]

@142, I'm also in Fla, Miami Beach. There is no dry air here. You have to seal the boxes in plastic bags before you put it in the fridge. Don't remove the plastic until after they have warmed up. There can only be so much humidity inside the bag so there's no reason to look for special dry air to put the boxes in for warming up.

I like the big ziplocks for flat boxes of plates.

For shipping my final holograms in resist I put the plate inside a bag and heat seal it closed. Now it's set for condensation and pressure changes during transportation.

[Dinesh]

Can you add a green dye to the green film and revitalize it?

I have no idea, I never tried to play with the emulsion. Although I don't understand emulsion chemistry, I do not think that just adding the dye would help as the emulsion gets as white as milk-in-water after development; I would expect that pure loss of sensitivity should lead to clear emulsion and no image after development. Anyway, can I use the procedure from Saxby's Practical Holography (p. 477)?

prepare mixture of:
100 cm3 of 3% solution of LiBr in 2:3 water/methanol mixture
2.5 cm3 of 0.2% solution of 1,1-diethyl-2,2-cyanine iodide in methanol
0.5 cm3 of 1% ascorbic acid solution in water

then soak the plate in the mixture for 1-2 minutes,
rinse the plate

I'm afraid I don't have the Saxby book, so I can't say whether that's a green sensitive dye. Danny Bruza has written a paper on green sensitization that you may be able to use: http://holoinfo.no-ip.biz/wiki/images/2 ... lsions.pdf

On the other hand, another problem may be that the emulsion has gone soft, the white you describe is characteristic of soft emulsions. So, you might try latensification or chemical hardening. For chemical hardening, you can use Kodak Rapid Fixer with hardener, or Chrome Alum. I believe that John Pecora, on this forum, has a hardening agent he uses for dcg which some members of the forum say they've had good results with. For latensification, I can;t say how much to latensify, but I'd start with simply hitting the emulsion with a photographic flash and see what happens.

[Martin]

Anyway, can I use the procedure from Saxby's Practical Holography (p. 477)?

prepare mixture of:
100 cm3 of 3% solution of LiBr in 2:3 water/methanol mixture
2.5 cm3 of 0.2% solution of 1,1-diethyl-2,2-cyanine iodide in methanol
0.5 cm3 of 1% ascorbic acid solution in water

then soak the plate in the mixture for 1-2 minutes,
rinse the plate

I'd suspect that adding another sensitizing dye won't be much of a help here. An ascorbate step may have some effect though. If there was emulsion fogging you might also consider a diluted EDTA bleach. A couple of years ago there was a pretty extended thread on this forum about revitalizing old AgX emulsions.