Apologies if you get this twice - my mail program is still having the odd
problems with the new setup.
Judy
A 'traditional' blue-print process uses:
Solution A
Ferric ammonium citrate (brown) 160 g per litre.
Solution B
potassium ferricyanide, 120 g per litre.
These are stated to be best mixed in equal parts a week or ten days before use
and kept in the dark - and then filtered just before use.
There are full directions in Cassell's Cyclopaedia (p67-8), one part of which
suggests that you should 'develop' with water containing 20 grains of citric
acid per pint for a 'brighter' print. It also says to use lime free water and
there are a few other hints and toning recipes.
Incidentally chemists will find enough hints in this work to enable the use of
much cheaper and more readily available iron compounds than ferric ammonium
citrate should they wish to experiment (the cheapest and most light sensitive
combination may well be ferric chloride with oxalic acid). It also notes that
the green ferric ammonium citrate gives much more sensitive papers with purer
whites than the brown salt.
The formula I've used with the green compound uses:
A: Ferric ammonium citrate, 36 g dissolved to give 100ml solution.
B: Potassium ferricyanide 16 g dissolved to give 100ml solution.
Mix equal volumes. I've normally kept these separate as they keep better.
As with Terry, I've experienced few difficulties in getting good results from
the blue-print. This surprises me slightly as both of us live in an area with
hard, slightly alkaline water which might have been expected to give problems.
Some papers I've found to produce an image that looks fine when wet, but on
drying is disappointingly dull - maybe this is a sizing problem? Or perhaps
quicker drying after coating would help.
Peter
On Fixing Shadows, Dragonfire and elsewhere:
http://faraday.clas.virginia.edu/~ds8s/
Family Pictures & Gay Pride: http://www.dragonfire.net/~gallery/
and: http://www.speltlib.demon.co.uk/
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