Re: Gum problem(s)

Date: 11/23/05-02:46:46 AM Z
Message-id: <>

I'm not a gummist, so you can take what I say with a grain of salt—either
pottassium or ammonium dichromate....

I always monitor my PT/PD printing with a hygrometer and adjust the RH in the
coating and drying room (my smaller bathroom, but that doesn't sound that
professional) using a humidifier. What I find equally important is to monitor
the drying time, since that affects both the amount of moisture in the coated
paper and coating as much as the RH. Is it possible that you may each use a
different combination of drying time that would cause variance in RH to make a
difference in one case and not in the other?

OK... back to my closet.

Mark Nelson
Precision Digital Negatives

In a message dated 11/22/05 7:04:56 PM, writes:

> hmm. Maybe it doesn't make so much difference at a lower dichromate
> concentration, or something; at any rate I do have to adjust my
> exposures for changes in humidity-- like when there's a dry spell after
> a long rainy season, I have to expose longer.  Not 20 minutes,
> certainly, but another minute or two. But even when it's dry, the RH
> here is seldom below 50-60%.
> I don't know how else to account for the fact that my exposure times
> are so short with the photoflood, than the humidity  of my environment,
> along with the established link between humidity and exposure required
> for hardening. How else would you explain it, unless the idea of long
> exposure times with photoflood is simply a myth and not based on actual
> observation?
> But this may just be one of those things we'll have to agree to
> disagree about.
> Katharine

Mark Nelson
Precision Digital Negatives
Received on Wed Nov 23 02:47:25 2005

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