Some people aim a fan at the glass , but frankly I'd rather take my
chances with the sun (even NYC sun). Also, since dichromate has a
continuing exposure effect after any exposure to white light, dragging out
the exposure by waiting for cooling would throw your timing off, if that
mattered.... Some people put a fan on the glass in sunlight, but
dichromate is quick enough so open shade would probably expose in 10
minutes or so & no need for fan....
> thought of at the time as "heat fog" which would give me a flatter and
> overall exposure needing longer washes or brushing out the hightlights. What
> brought this to mind was your description of flakiness. A very common
> problem when I had long exposures, although at the time I thought it was the
> thickness of the emulsion. In one of my condensor enlargers is a sheet of
> greenish tinted glass i.e. "heat absorbing glass".
In my mind the kind of hazy stained effect of a fogged gum emulsion (heat
or light) is more or less the opposite of the flakiness I'm getting: the
part that flakes off reveals totally white paper base. Whatever it is I'm
having, it's pobably at least somewhat related to the thickness of the
emulsion because I can see it begin in edges of the print where emulsion
has built up slightly.
However, you're suggesting that the green glass over the vacuum table
absorbed more heat than the Starphire. That's a very ingenious thought --
if so it might or might not account slightly or largely for what I'm
seeing. However, there's very little heat at the paper plane -- it's
absorbed by a high tech glass directly under the bulb...
Still, it does seem that *something* is absorbed or reflected or
transmogrified... I'm considering turning on the airconditioner. Did you
make prints with the old Smith-Victor, by the way? In the beginning I
tried photo floods (that's what the books told you to do), a cyanotype
took an hour --- & was a mere shadow of its potential self....
cheers,
Judy