RE: UV Box Heat Fogging?

I don't think fogging in your case is caused by heat. I expose prints
consecutively and my UV fluorescents don't get so hot (they get warm but
definitely not hot). I didn't read anything about heat fogging of vandyke
too. The safest way of testing if vandyke gets fogged with heat would be
heating the coated paper (with a hairdryer for instance) and exposing for
standard time. If it gets fogged then we can say heat fogs vandyke. But this
wouldn't indicate the fogging is caused by heat in your specific case. Heat
from UV fluorescents is not the same as heat from a hairdryer. The result
you're getting is caused by the fact that the negative density and color you
use is not 100% opaque and after enough (excessive in your case) exposure,
you get tone in the print. You can try it with a stouffer step tablet too;
if you expose enough you will get tone in the 31st step.

Regards,
Loris.

-----Original Message-----
From: Michael Koch-Schulte [mailto:mkochsch@shaw.ca]
Sent: 22 Kasım 2005 Salı 21:30
To: alt-photo-process-l@sask.usask.ca
Subject: Re: UV Box Heat Fogging?

What I was trying to do was to see what the limits of a colorized negative
are in regards to blocking UV. I'm normally printing to VDB around 1.8-1.95
which takes about six minutes. For my own curiousity I doubled that time,
and then doubled that again (6, 12, 24 minutes). At 24 minutes things
weren't looking like what I thought they would. I wondered if heat energy
was becoming a factor on the emulsion exposure overall. Hence the question,
does heat fog exist in these situations?

~m
Received on Tue Nov 22 13:52:23 2005