Help to Identify & Stop Deterioration

[mistermonday]

Below is a photo from 1958. The image is developing shiny gray patches. It is particularly bad along the edges but patches are now forming randomly in other area. Does anyone know what type of print process this was and how to prevent the rest of the image from going the same way?
Tks & Regards,
Murray

[CJ Swartz]

Murray, I haven't responded previously because I have no personal knowledge, and there are members here who have worked in this area. Seems like none have logged on recently or seen your post.

My only thought is whether it is the "silvering" that we have run into during retouching challenges here on the forum -- I can't specifically identify "silvering", but here's a link to a Photo.net discussion about silvering and possible solutions for the problem -- Michael Briggs response (fourth post down) talks about "dichroic silver" and recommends a book.

http://photo.net/bboard/q-and-a-fetch-msg?msg_id=005FhX

Hope this helps, or at least "bumps" your question to the attention of someone knowledgeable.

[mistermonday]

CJ, thanks I will check it out tonight.
Regards, Murray

[Cameraken]

Hi Murray.

The reason I did not respond to this was because this is very hard to diagnose and to provide a solution.

The method of making sepia toned prints was two step process.

1) make the B&W print
2) Add the sepia tone

The underlying B&W print in your sample 'looks' OK. So I would suspect a problem in the toning.

Sepia toning was a 3 step process
1) Bleach
2) Redevelop
3) Wash

Here is the problem because many different chemicals were used to sepia tone.

We used potassium ferricyanide for the bleach
sodium sulphide for the re-develop
(This combination gave a warmer tone)
and a water wash

We used to sepia tone many prints at once (times were not too critical) and air bubbles or papers sticking together could always cause problems.

After the toning all the prints were washed for about 30 mins but again prints could stick together and not get washed adequately.

All the finished prints would look OK but I guess that many years later an inadequate bleach/redevelop or wash could cause this type of deterioration and without knowing which chemicals were used I think this problem is impossible to answer.

All I could suggest is to give the prints another good 30min wash. This may not help but should do no harm.

Hope this helps.

Ken.

[mistermonday]

Ken, thanks very much for the reply and for the explanation which makes sense. On close examination, in addition to the area which have turned silver - gray, there are some patches where all of the coating has gone revealing what must be the base B&W image. I will restore it from a scan and depending on the results decide what to do with the original.
So now the reverse quest: Is there an easy way to remove the toning layer and strip back to the B&W?
Thanks again for your reply,
Regards, Murray

[Cameraken]

Hi Murray.

I have never heard of a reversal process to turn a sepia print back to black and white.

The simple way is to make another B&W from the negative (or a scan)
If the original neg's are not available then halting the deterioration is probably the best you could hope for.
There is an interesting article here

http://en.wikipedia.org/wiki/Photographic_print_toning

It explains how some toning processes actually makes B&W prints more stable whilst other toning processes can reduce the life of the prints.


Completely off topic.
We used to use this toning method as a base for hand colouring B&W prints.
We painted on the bleach (potassium ferricyanide) with a brush, avoiding any areas that we wanted to remain black or white.
After the redevelop (sodium sulphide) we had a 'selectively toned' print which we then hand coloured with oil paint.


Hope this helps.

Ken.