Toning for protection

[piticu]

Could you fellow forum members suggest some toners for protecting cyanotypes and van dykes? I don't care about colors, only about the protection level they provide.
Thank you

[Loris Medici]

You don't need to tone cyanotype for protection, just keep it away from alkali materials + make sure the surface is in contact with oxygen (do not apply an impermeable coating) and that's all. It's one of the most stable alt-processes around...

OTOH, you definitely need to tone Vandyke for longevity. (Plus, pay a good deal of attention to the paper selection and washing/clearing steps during processing...) One of the best toner options for Vandyke is the gold-thiourea toner. Search the web for the exact formula.

Regards,
Loris.

[piticu]

if i don't tone the cyanotypes i make they fade overnight due to acid buffers from the paper. i don't have access to other papers so… you see… i have to tone cyanotypes and i was wondering if there's something else besides tannin.
i understood that ferous tanate is very very stable regarding oxidizing over time, maybe i will stick with tannin. i ordered some wine tannin from a guy in sweeden really cheap: less than 3e including shipping to romania for 50g.

[Loris Medici]

It's not the acid then, cyanotype actually likes acid environment. If your untoned cyanotypes are fading, then that's a good indication that your paper has calcium carbonate alkali buffer. In no condition you should attempt to print cyanotype on alkali surfaces!

If you can't obtain any other paper, then just neutralize the alkali paper (BEFORE PRINTING!) by putting it in a simple 2% hydrochloric acid neutralizing bath for at least 2 minutes (or until there's no more fizzing), changing the paper orientation halfway. Just rinse/wash well the paper later. (At least 30 minutes and 5 water changes.)

The image will be pretty stable on neutral (or acidic) paper. As a bonus, you'll notice a significant speed increase along with much higher image density.

BTW, I can get 0.5 to 1 kg (depending on the make/packaging) tannic acid here for that price. See winemakers in your area; they'll most certainly have it.

Hope this helps,
Loris.

[piticu]

It's not the acid then, cyanotype actually likes acid environment. If your untoned cyanotypes are fading, then that's a good indication that your paper has calcium carbonate alkali buffer. In no condition you should attempt to print cyanotype on alkali surfaces!

that's what i said my friend, „acid buffers from the paper“. of course it's some sort of calcium carbonate

that's a good advice about neutralizing the papers before coating. i didn't think about it although i believe i've read about it - it was oxalic acid instead of hydrocloric. i will try with azotic acid, i got around 100ml 60%.

in romania, tanic acid runs around 100e per 100g! it's insane!

[Loris Medici]

It's anti-acid buffer or more correctly (as I and everyone else - except you - use it) "alkali buffer"... See the literature; if you say "acid buffer" what others will understand is that the paper is acid (and buffered to remain acid), not alkali as in your case.

What is azotic acid? You're probably referring to nitric acid. Probably it's safer to use hydrochloric acid, this is usually present in ordinary household as calcium remover / wc cleaner. (15% max. strength, you'll just add it to some water to dilute...) 60% nitric acid is nasty; I'd stay away from it!

[piticu]

apologize for my bad language. you got it right, azotic acid means in my head HNO3 or nitric acid

[piticu]

it just hit me: i can also use citric acid, i got plenty of it. for sure i will try them both

[Loris Medici]

Unfortunately citric acid won't do the job: Citric acid + calcium carbonate = calcium citrate, and calcium citrate is highly insoluble, therefore won't leave the paper. Calcium chloride (hydrocholoric acid salt) or calcium nitrate (nitric acid salt) are highly soluble and will leave the paper.

P.S. Won't do the job cleanly I mean. Probably it will neutralize the buffer but will leave an alien reaction product in the paper, which is something we usually don't want.

[piticu]

thanks for helping me not wasting my time and chemicals