Re: bromoil (once again)

Pollmeier Klaus (100561.2417@compuserve.com)
27 Jan 96 09:49:13 EST

Jennifer Jacobberger wrote:
> he uses a post-final fixing bath of diluted sulfuric acid to bring out the
relief, followed by a wash consisting of water that must be no colder than the
acid-why must the water be no colder? What happens if it is not? And where (if
anywhere) should the pre-ink drying be placed? Before or after the acid
bath/wash?<

The hint on the wash water not beeing colder than the acid bath is from A.
Mebes: Der Bromoldruck, 1921. 272 pages of perfectly researched information...
Cold water shall lead to problems during inking. However, in this special case
he does not explain the chemical reason for this recomandation, but quotes the
inventor, C. Welborne Piper, who said the same in 1908, Phot. Journ. p. 69.

If you want to dry before inking (I don't dry it, but others say the inking up
is easier then. If you do, the print must be bone dry!), the acid bath should
follow after resoaking in water and before the swelling bath.

>What is going on when in the deepest shadow areas, complete bleaching does not
seem as though it is ever going to occur (like after 19-20 minutes) and it just
turns a sort of brown? Although it may not be bleached fully, is it still going
to be completely tanned and able to pick up ink appropriately?<

Mebes mentiones 48 (!) formulae for bleaching baths, each one probably requiring
different bleaching times. But in general 2-3 min. should be sufficient to let
the image disappear and 4-6 min the total bleaching time. Much too long a
bleaching may cause overall tanning. The brownish appearance of the remaining
image may be due to a non-acid fixer or insufficient washing after fixing. Don't
use just a 10 percent hypo solution, as often recommended, but an acid fixer
made by warm water 1.000 ml, hypo 150 g, after cooling down add 15 g of
potassium metabisulfite.

Good luck,

Klaus Pollmeier