durability of alternative processes

[morado]

Does anybody know the durability of the different altenative

processes? I use in particular cyanotype and salt paper and I would

like to know how long will they last. The questios also goes for

toning as I did some blue toning with a formula similar to cyanotype.

I know selenium and sepia toning will make the picture last longer,

but what about some other kinds of toning? and what about polaroid

transfer?

 

Thanks a lot

 

Victor

[silent1]

Cyanotypes are known to fade from exposure to light and atmospheric pollutants, though if fully washed and well protected, they can last a century or more. Salt prints can fade or discolor, either if not adequately fixed or washed, or from environmental contamination of the same sorts that would damage a silver gelatin print. Salt prints, however, can be toned in regular selenium toner, brown (sulfide) toner, or with gold or platinum/palladium toners, all of which will improve the permanence of the image forming particles, at the expense of a color change that might or might not be desirable.

 

That said, their are a fair number of (seemingly untoned) salt prints around from the latter half of the 19th century that are still in good condition. Storage is a big part of this; air with a trace of hydrogen sulfide in it (just to name one culprit) will damage silver in any form over time, while a print stored in good conditions will last well as long as it was fixed and washed properly to begin with.

[michaelkh]

Donald,

 

is it true that cyanotypes 'toned' in tannic acid (I'm sure there's a better word for what

actually happens in this case) become more durable?

[gauthier]

Micheal. I wonder the same thing. The only answer I can give for sure is that tannic acid or tea toned cyanotypes resist alkaline environmnents very well. I once tested a tea toned cyanotype in a strong, warm solution of sodium bicarbonate: it didn't bleach at all.

[joe_lipka3]

I'll bet if you went to www.alternativephotography.com, you could probably find out a lot of information on cyanotypes.

 

Tannic acid and sodium carbonate in a second bath can be used to tone cyanotypes to brown-black.

[silent1]

Unfortunately, I don't know whether tannic acid toning preserves cyanotypes -- I'm only repeating what I've read, having never made a cyanotype, much less stored one for 150 years.

 

One can make a good guess, though; if, as reported, the toned prints don't bleach in a bicarbonate bath, where the untoned do, it's likely the toned pigment is more stable under at least some conditions.

[gauthier]

Donald: One of the concerns about cyanotypes is that they generally hold better in acidic than in alcaline environments. Papers with a reserve of alcaline material, for instance, can be very harmful on the long run. Tea toning (which is not tannic acid but some organic compound that behaves very similarly) makes a cyanotype resistant to alcaline solutions (my strong sodium bicarbonate + arm water test) that would seriously bleach an untoned image in a matter of seconds and make it fade away in a couple of minutes. So, tea toning (and presumably tannic acid toning as well) protects your cyanotypes against the most prevalent source of fading.<div></div>

[michaelkh]

Lovely photo, great answers - you have got to love this site and it's contributors!