So what is it, how does it protect the image and how much toning does it take to get to this level of protection?
@Alex Benjamin was right.
Take a look at the ingredients in a selenium toner, and you'll be able to spot what the main source of sulfur is (and the pH that makes it stink).
Here's the principle as isolated into Sistan/Adostab.
Take a look at the ingredients in a selenium toner, and you'll be able to spot what the main source of sulfur is (and the pH that makes it stink). That Selenium toners made materials more 'archival' was essentially purely coincidental. A tiny residue of Sulfur is the key here - which basically means use hypo-clear (not hypo-eliminator) and a reasonable wash, but don't overwash. The point of Se toning should be for colour/ density change (by which point you've more than sufficiently sulfurised it) rather than for any claims of archivalness - it just happened to be the one reasonably common toner that could be diluted enough to not affect image colour significantly (and which has other archival test uses for adequate fixing).
Water, a form of pseudourea and methanol. I can see how this might act as a radical scavenger and/or donate sulfur similarly as discussed above, but IDK for sure.Do you happen to know the composition (or the main ingredient) of the Fuji Ag guard "toner" I know its different from Sistan.
OK, that story. But the problem with that is that selenium toning has been found to be unreliable in this capacity: https://www.largeformatphotography.info/toning-permanence.html
One chief benefit of archival processing is that you're able to say that you do it.
Many don't like the "eggplant" tone that strong selenium toning imparts to many papers.
FWIW, I prefer the image tone change that the many different sulfide based toners - like sepia toner - impart, and it is a bit easier to tell when they have been fully toned.
And don't forget the Selenium ribbon you're allowed to wear on your uniform.
@RalphLambrecht this is so helpful! Thank you for sharing.
If you want an archival print the best route is to double tone.
It is worth buying Ralph's book for the sheer range and depth of coverage of "things photographic"
pentaxuser
Sorry I was away.Well the results can be better in terms of "looks" but I didn't think double toning was necessarily the best from an archival aspect? It may well be nearly as good and on the basis that it may look better then it may "win" - just not on archival grounds
pentaxuser
It is important to understand that the OP, @dcy , is currently printing exclusively on RC paper.
Which itself can be properly fixed and washed for longevity, and toned for that purposes as well, but the methods vary slightly.
For example, there is no point to using a wash-aid to speed full washing, and many RC papers respond differently to toning.
Although curiously, one print my Dad had framed for hanging on the wall back then seems to be "silvering". Still a perfectly good photo, but seems to be taking on a slightly metallic look when viewed from a certain way. I don't know the technical name that's called. The moral of the story is that a little washing goes a long way without need of toning.
Well, apparently, the washing didn't go enough of a way to prevent that particular print from silvering out. That it happens to that particular print and not the ones stored in boxes is sensible as it's subject to the influence of pollutants, changes in humidity and temperature more so than the stored prints. The underlying cause of why it's happening already after a few decades to your print would most likely be insufficient fixing and/or insufficient washing - although arguably (see @Lachlan Young's argument above) too effective a wash also can be detrimental. In principle, silvering out is a natural process, but it starts quicker on a less-than-archivally processed print and can be accelerated by environmental conditions.
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PMG Silver Mirroring
www.conservation-wiki.com
And it's not "silvering out", really.
That's what silvering out looks like at the start.But at a certain angle you can see a bit of silvery appearance, mostly confined near the edges.
Sorry. Didn't realize it was about RC paper and you are absolutely right. Good fix and wash is already enough.
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