Longevity of Van Dyke prints

[Doc W]

I read somwhere that Van Dyke prints are not as permanent as I thought. Is there any truth to this?

 

[removedacct1]

It is my understanding that Van Dyke Brown prints are not nearly as "archival" as many other processes.

 

[fgorga]

I read somwhere that Van Dyke prints are not as permanent as I thought. Is there any truth to this?

Well, "not as permanent as I thought" is a pretty vague statement, but I'll attempt a reply based on a very little bit of experience with the Van Dyke Brown process (I prefer salted paper, myself) and my knowledge of chemistry in general, which is somewhat more extensive.

Silver-based prints, in general, are not as stable as those made with platinum, palladium or gold for the simple reason that silver is more reactive than the other metals mentioned. Thus a silver-based print will react with "stuff" (there's a good precise chemical term! ) in the environment more readily than prints made with the noble metals.

This issue can be over come to some extent by toning silver-based images with the noble metals, gold being most commonly used or with selenium. Toning prints with noble metals basically plates the silver grains comprising an image with a less reactive metal. Toning with selenium, converts the metallic silver to silver selenide which is quite stable, I have exactly zero experience in toning VDB prints, so you're on your own as far as specifics go!

Additionally, being an iron-based process, VDB has the potential issue of residual iron. If one fails to remove all the iron from a print on ends up with an unstable product. Basically, the print will "rust" over time as it sits exposed to the air.

I hope that this is a useful response.

 

[nmp]

Historically these "brown print" processes and analogs did have a bad reputation - longevity wise. Silver in these prints are in much finer (sub-micron) sizes than the conventional silver gelatin prints or presumably even salt/albumen prints (as signified by their yellowish red to brownish colors) so they can be expected to be more vulnerable to environmental degradation.

This from Ed Buffaloe at Unblinking Eye:

"A longstanding concern has been voiced about the archival qualities of the brown print. This is due to the fact that many early brown prints did not last long, and my own experience bears this out. The modern consensus seems to be that, if it is processed properly, the brown print will have the same longevity as any other silver process. For the brown print there are four things to consider to assure print permanence: (1) removal of iron compounds, (2) sufficient fixing, (3) sufficient washing, and (4) toning--not necessarily in that order. My personal experience tells me that toning is not optional. Untoned prints keep fine in a closed box, but once exposed to light and atmospheric pollutants, they begin to deteriorate almost immediately."

More: https://unblinkingeye.com/Articles/Ferric/ferric.html


:Niranjan.

 

[koraks]

Silver in these prints are in much finer (sub-micron) sizes than the conventional silver gelatin prints or presumably even salt/albumen prints (as signified by their yellowish red to brownish colors) so they can be expected to be more vulnerable to environmental degradation.

That's one aspect of it. Another potential issue is with the iron salts used in the sensitize that are difficult to wash out entirely, as they can be partly converted to insoluble iron salts in the presence of compounds in the paper of processing liquids. Afterwards I can very well imagine these iron impurities in the final print contribute to image degradation.

However, if a VdB is properly processed and especially if it's toned to completion with gold, platinum or palladium toner, it should be quite permanent.