Forum member NedL has done a lot with calotypes and if I recall right has experimented with gallic acid. I'm sure he'll spot this thread and weigh in anyway, but You could try searching for posts by him on calotypes.
I have plenty of 2mm glass so I'm going to start with the glass sandwich type holder.
Hi Ned
Plan is to make the 'dry' type (silver iodide) on cotton based paper and develop using the chemical used by Fox Talbot.
I have plenty of 2mm glass so I'm going to start with the glass sandwich type holder.
I'm starting quarter plate and already shoot whole plate so I can move up later.
I've just discovered how expensive gallic acid is here in the UK! (£73/100g)
I already salt print.
I'll post up any results (good or bad) for your review.
Thanks for your reply
Simon
Compared to the easy and relatively inexpensive availability of so many things in the US as against the UK, this is perfectly true ... however, SIlverprint (who are quoting you that absurd price, I think) is not the only supplier of photochemicals out there, and they have become much more expensive for raw chemicals over the past couple of years.Things are just expensive here!
Simon
...Of course, you can attempt to extract gallic acid from oak galls (there's a clue in the name) - if you have a ready supply of them - by a process of fermentation and treating the resulting must with acid. I think Ned has a couple of references for 19th Century papers on how to do that (?).
and... gallic acid which is prepared from finely powdered gall nuts and macerated for some days with cold water. This decanted liquid is exposed to the air and allowed to become covered with mould. An addition of yeast is advantageous. The gallic acid which separates is purified by recrystallization from boiling water.
British Journal of Photography from 1883 suggests that the fermentation method takes several weeks.Another method of making gallic acid is by boiling the aqueous extract of galls with 5 per cent by weight of sulphuric acid for about five hours. The reaction is complete when a drop of the solution gives no precipitate with a gelatin solution.
Well, perhaps one of those accidents like RoquefortWhat always concerns me is who thought of fermenting oak galls in the first place and why?
So... if I understand correctly, you're making calotype paper, putting it in a camera, and taking photos with it? 'Cause I've been looking all over the place for anyone doing this and came up with nothing 'til here.Hi Ned
Plan is to make the 'dry' type (silver iodide) on cotton based paper and develop using the chemical used by Fox Talbot.
I have plenty of 2mm glass so I'm going to start with the glass sandwich type holder.
I'm starting quarter plate and already shoot whole plate so I can move up later.
I've just discovered how expensive gallic acid is here in the UK! (£73/100g)
I already salt print.
I'll post up any results (good or bad) for your review.
Thanks for your reply
Simon
So... if I understand correctly, you're making calotype paper, putting it in a camera, and taking photos with it? 'Cause I've been looking all over the place for anyone doing this and came up with nothing 'til here.
A whole lot of Google results seem to suggest that calotype printing comes only from contact printing - a fine chicken-egg absurdity there...
Referring to calotype as just a contact process always begs the question: what mysterious process did Talbot use to take his photos and produce these paper negatives?
Given this, i've skimmed the Flickr calotype group previously and not seen any clear info on camera usage/making negatives, but I haven't looked deeply. I'll reinvestigate.
Cheers.
Edit: here's a link.
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