Re: Gum Woes II

In my opinion, your gum/sensitizer ratio ("3ml gum + 1 ml am. di. soln") is
causing problems. My 'standard mix' is 1 part gum to 1 part sensitizer. I
never deviate beyond a 2:1 or 1:2 gum/sensitizer ratio. It's been my
experience that greatly increasing the amount of gum, as in your case, will
usually cause flaking and uneven coverage. "Specks never dissolve" could be
caused by tiny clumps of pigment that have not been thoroughly mixed into
the gum. I use a stiff-bristled brush to vigorously mix pigment into gum.
Then I mix the gum/pigment solution with the sensitizer.

Try printing with a 1:1 gum/pigment ratio. Add pigment as needed. Most
carbon or lamp blacks are very strong, requiring relatively little pigment
be added to the mix. I don't see how dampening the print prior to coating
would be necessary or advantageous.

Best regards,
Dave in Wyoming

----- Original Message -----
From: "Gary Nored" <gnored@centurytel.net>
To: <alt-photo-process-l@sask.usask.ca>
Sent: Sunday, November 02, 2003 3:13 PM
Subject: Gum Woes II

> Rats! Just when I think I might have, sort of, gotten started, maybe
> a little bit, printing in gum bichromate, two new problems arise.
>
> I've gotten a single layer gum bromide to work tolerably well. I
> decided that it was time to take the next step. I wanted to add
> another color.
>
> My first layer was a coat of 3ml gum + 1 ml am. di. soln. + 1cm
> worm of pigment mixture. I dried it, exposed it to skylight for a few
> minutes, and then "developed it." Looks fine. There was no picture
> -- this was just a color wash. Dumb way to do that, but too late :-{o
>
> First Problem
> For the second layer I chose a black pigment (about half the
> usual), but otherwise using the old formula (James'). When
> applying the gum, tiny (bubbles?) appeared on the trailing side of
> the brush, leaving little spots of exposed color behind. No amount
> of brushing would suffice to close the holes and make them stay
> closed. There aren't too many of them, but ... What's going on
> here?
>
> Second Problem
> The second layer flakes (is that the term?); ie, little spots (more
> than were visible during coating) fall off in the wash, ruining the
> image. The specks never dissolve. What's going on with that?
>
> Any ideas what I'm doing wrong here? Should I dampen the print
> before applying the second sensitized coating?
>
>
> Regards,
> Gary Nored
> http://home.centurytel.net/Gary_Nored/
>
Received on Mon Nov 3 08:07:17 2003