Marco B
Subscriber
Hi all,
Now I have no doubt that almost any Pt/Pd print will easily outlast any untoned silver gelatine print, but one thing kept nagging me...
It is a not much discussed topic here on APUG, almost seems to be avoided, but I already knew Platinum (and probably Palladium as well), is a rather strong and effective catalyst, speeding up and enabling chemical reactions. One of the reasons it is used in car's exhausts.
Now I had already seen and partly read James M. Reilly's
“Care and Identification of 19th Century Photographic Prints”
document showing a Pt/Pd print been in contact with another paper, leaving a visible "mirror" image on the other paper by it's catalytic activity. See the attached image in this post. This is not just a "harmless" discolouring of the paper though... as I now recently read an article by Mike Ware about his Gold based Chrysotype process, referring to "embrittlement" of the paper base of Pt/Pd prints. While the highly noble and stable metals themselves will last indefinitely, the paper base and photographic image itself might be lost at some point...
Chrysotype: Photography in Nanoparticle Gold
Mike Ware literally writes in this document:
"It has already been stated that chrysotype resembles the better-known, and at one time widely acclaimed, platinotype process (38). New chrysotypes are extremely light-fast and resistant to chemical attack; they therefore enjoy an archival permanence at least equalling, and perhaps surpassing, that of the platinotype. The conservatorial problem which has beset all historic platinotypes arises from the high catalytic activity of platinum black, which can bring about the aerial oxidation of SO2 to SO3, thus causing serious acid embrittlement of the paper base by sulphuric acid formed in situ. In contrast to platinum, nanoparticle gold has a very low catalytic activity in this respect (39), so this problem should be absent from chrysotypes. The longevity of the paper substrate will also be enhanced by the alkaline conditions of the wet processing, in contrast to the hydrochloric acid clearing baths sometimes used to process platinotypes."
Both James M. Reilly and Mike Ware are highly authoritative and credible sources, and in addition the example image shows that we are not only talking of a "theoretical" option, but a real thread to the very long term survival of the Pt/Pd print.
As the process described by Mike is depended on the presence of sulphurdioxide gas, the generally good recommendation for photos of proper framing behind glass, especially in the polluted environment of an urban city, seems a necessity. It will probably be very effective as a conservation method, as it simply blocks air circulation at the surface of the print, keeping SO2 load to an absolute minimum. In addition, but all Pt/Pd printers are undoubtedly already doing this, only the highest quality 100% cotton rag cellulose papers seems recommendable, to give the paper the maximum chance of long term survival.
What are your thoughts and comments on this issue?
Marco
Now I have no doubt that almost any Pt/Pd print will easily outlast any untoned silver gelatine print, but one thing kept nagging me...
It is a not much discussed topic here on APUG, almost seems to be avoided, but I already knew Platinum (and probably Palladium as well), is a rather strong and effective catalyst, speeding up and enabling chemical reactions. One of the reasons it is used in car's exhausts.
Now I had already seen and partly read James M. Reilly's
“Care and Identification of 19th Century Photographic Prints”
document showing a Pt/Pd print been in contact with another paper, leaving a visible "mirror" image on the other paper by it's catalytic activity. See the attached image in this post. This is not just a "harmless" discolouring of the paper though... as I now recently read an article by Mike Ware about his Gold based Chrysotype process, referring to "embrittlement" of the paper base of Pt/Pd prints. While the highly noble and stable metals themselves will last indefinitely, the paper base and photographic image itself might be lost at some point...
Chrysotype: Photography in Nanoparticle Gold
Mike Ware literally writes in this document:
"It has already been stated that chrysotype resembles the better-known, and at one time widely acclaimed, platinotype process (38). New chrysotypes are extremely light-fast and resistant to chemical attack; they therefore enjoy an archival permanence at least equalling, and perhaps surpassing, that of the platinotype. The conservatorial problem which has beset all historic platinotypes arises from the high catalytic activity of platinum black, which can bring about the aerial oxidation of SO2 to SO3, thus causing serious acid embrittlement of the paper base by sulphuric acid formed in situ. In contrast to platinum, nanoparticle gold has a very low catalytic activity in this respect (39), so this problem should be absent from chrysotypes. The longevity of the paper substrate will also be enhanced by the alkaline conditions of the wet processing, in contrast to the hydrochloric acid clearing baths sometimes used to process platinotypes."
Both James M. Reilly and Mike Ware are highly authoritative and credible sources, and in addition the example image shows that we are not only talking of a "theoretical" option, but a real thread to the very long term survival of the Pt/Pd print.
As the process described by Mike is depended on the presence of sulphurdioxide gas, the generally good recommendation for photos of proper framing behind glass, especially in the polluted environment of an urban city, seems a necessity. It will probably be very effective as a conservation method, as it simply blocks air circulation at the surface of the print, keeping SO2 load to an absolute minimum. In addition, but all Pt/Pd printers are undoubtedly already doing this, only the highest quality 100% cotton rag cellulose papers seems recommendable, to give the paper the maximum chance of long term survival.
What are your thoughts and comments on this issue?
Marco
Attachments
Last edited by a moderator: