Re: Wash off

["Jeffrey D. Mathias" <jeffrey.d.mathias@att.net>]

William Marsh wrote:
> ...
> 4 - 5 min. exposure gives a deep black in the edge, but enough coating
> is coming off to turn a pint of developer noticeably greyish just doing
> 3 test strips and one print.  Even though the edges are black, it stands
> to reason that emulsion must be coming off the image areas as well,
> weakening them.

Technically the coating is not an emulsion.  Several things might cause
this "bleeding" you have noticed.

+  As Kerik has mentioned, this paper may need to have the coating
mixture soak in better.  Several papers require this, but others may
not.  However, do not let the fresh coating sit around for more than an
hour before exposure as this will likely degrade the print quality.  Try
a paper like Bienfang 360 and see if the "bleeding" still occurs.

+  Are you using EDTA in the coating mixture?  Too much can cause
"bleeding".  Try lowering the amount of EDTA if present.  Is EDTA added
to the sensitizer?  Try a different batch or source of sensitizer.

+  What are your metal salt solution strengths.  Too high a solution
strength will contain excess metal which becomes wasted and washed off
during processing.  There is a lot of information on the solution
strengths in my guide (available at link below).  Check out the studies
for optimization and verification of process equations and formulas. 
Many of the formulas and books out there don't put in enough metal, but
some put in too much.  Not enough will result in a weak print, too much
will be wasted.

Some metal in the developer should not hurt it; some even claim it to be
beneficial.  However, used sensitizer solution can eventually build up
and result in a fogging of prints.  Usually enough of the developer is
carried away that replenishment of fresh keeps this sensitizer level
down, but really old developers may have this problem.

-- 
Jeffrey D. Mathias
http://home.att.net/~jeffrey.d.mathias/