Bruce {and everyone}
I don't have the math at this moment to detirmine whether my dilution of 37%
acid = 3% solution. {laughing}
However, when I used this solution out of doors it had a FAST effect - I
mean 5 seconds was plenty, but this would depend on the extent of exposure.
Most of my experiments this past summer were out in the strong afternoon
sun, and I found that many of my prints required less than 2 minutes of
exposure.
This is compared to the 5-6 minutes exposure plus up to 30 seconds in the
hydrochloric acid solution when printing indoors {and coating paper under a
yellow "bug" light} with a UV machine.
Regarding the different tones achieved with different chemicals:
Hydrochloric acid produces a more intense blue, quite a bit richer than the
blue one would recieve once the print dries.
I have a great cook-book I recieved when learning alt-processes at York
University, and though I haven't tried them my professor, Jack Dale, has and
I'm certain they should work:
To convert Cyano to black tones:
place print in solution of 3 drops Nitric Acid added to 1litre water for two
minutes
transfer to bath of 14g Sodium Carbonate + 160cc water - leave till image
disappears and then reaapears with an orange tone
transfer prin to third solution of 14g Gallic Acid + 160cc water - black
tones will appear
wash 30 min.
Brown tone conversion:
place print in solutioni of 28cc Strong Ammonia + 240cc distilled water,
will take aprx. 5 minutes for print to lose all its color
rinse in running water 1 minute
transfer to solution of 14g tannic acid + 750cc distilled water
Does anyone know of Canadian dealers where I could order most of the
chemistry needed for cyano, Vandyke and Gum Bichromate printing?
thanks
>Hi Risa
> It sounds like you are using 3% solution of hydrochloric acid which
>I tried and got almost no effect. Could I have done something wrong, some
>one else mixed the chemicals? As I recall the hydrochloric acid was
>supposed to produce a green tone but nothing happened and I didn't
>investigate further.
> I now use a 10 % solution of potassium dichromate which produces
>what I would call a navy blue colour( this is on hand made paper). The
>effect happens very quickly (30 seconds) and adds contrast to the print. If
>you are getting results with the hydrochloric acid than I will try again. I
>would be interested in any other methods that people use to produce other
>tone. I have used tannic acid but the brown tone was not what I was
>looking for.
>
>T/\/\/\/\/\|| Bruce McCaughey
>|| ||---| dcav@unixg.ubc.ca
>|| ||---| Vancouver, Canada
>0\/\/\/\/\/||
>=============
>
>
>