U of S | Mailing List Archive | alt-photo-process-l | Re: BL light box 'blues'

Re: BL light box 'blues'

Hi Robert..

That thought about sawing a couple of inches off the bottom of the box had
crossed my mind, but I was a bit worried about the greater possibility of
less even light with the tubes being the one inch apart. I'll try a few more prints
and see how it goes. If the long exposure times persist I'll take a couple of inches
off... and if there are any problems with 'banding', I can always raise it an inch or so
by adding some 'risers' on the sides and back since I still have some strips of the half-
inch baltic birch left over.

Re: the BL tubes, I believe I read that while being a bit "less safe" than the BLB, they are closer to
the preferred wavelengths.


On 30-Mar-09, at 6:17 PM, Robert Newcomb wrote:

I'm no expert, but you might consider moving the light closer to the printing frame. The inverse square law would indicate that if you half the distance you'd pick up two stops worth of exposure speed - I think.
And, is a BL lamp the correct one - should it be BLB?
Robert N.

---- Original message ----
Date: Mon, 30 Mar 2009 14:48:59 -0600
From: Ken Sinclair <photo1@telusplanet.net>
Subject: BL light box 'blues'
To: alt-photo-process-l@usask.ca

Have recently decided to intensify my interest in non-silver, I
constructed my
new UV light-box using 10 BL tubes presently 5 inches above my
printing frame.

So that I could use the same negatives for both silver-gelatin,
Cyanos and VDB
I switched to Pyrocat as a developer... and I must admit, they do
look "sweet".

A few years ago my southern Alberta summer sunlight exposures for
Cyanos were
running around the eight minute mark... which expanded to around two
and a half
hours in the rather weak December sun.

The exposure times I expected using the new 24" BL tubes are nowhere
as short as I had
hoped...  Cyanotypes seem to be requiring around 40 to 50 minutes
while I have not
yet reached the 'end-point' for acceptable VDB exposures, it seems as
if 60 -70 minutes
might be the absolute minimum.

I do not have a stouffer wedge to assist reaching my standard
exposure times, my patience is
wearing (as my frustration level rises).

I have just put a VDB out on the deck to enjoy some natural UV rays
from the sun
for a time comparison...

Are my BL light-box test exposure times "out of line" with times
experienced by others?


Quando omni flunkus moritati (R. Green)

Quando omni flunkus moritati (R. Green)