Re: GUM TESTING/CLEARING

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From: The Painted Horse (paintedhorse@in-tch.com)
Date: 07/16/03-11:59:08 AM Z


Thanks Katharine.
I did notice that the images were a tad weaker in appearance to the one
that cleared without a problem. All the images were exposed on the same
day with the same exposure time. Maybe I didn't wash them long enough?
I'm still new at all this. So much to learn...Just glad it's not the
pot metabi.
Regards,
Bill-

Katharine Thayer wrote:
>
> Hi Bill,
> My guess is that the gum in these particular images may not have been
> really hardened in the first place, possibly due to underexposure, and
> it dissolved when re-wetted. A properly hardened gum image should not
> dissolve when put back in water, with or without clearing compound in
> it.
>
> According to some experts, potassium metabisulfite is the gentlest of
> the potential clearing solutions available, and sodium bisulfite is the
> harshest. I can't comment on that assertion because I have needed to
> clear very few of the hundreds of gum prints I've made over the years,
> and the only clearing solution I've ever used is sodium bisulfite. But
> I'm willing to take others' word in this case, and I've never seen
> sodium bisulfite lift an image off the paper, so it stands to reason
> that potassium metabisulfite would be even less likely to do so. That's
> a longwinded way of saying I don't think it's the potassium
> metabisulfite that's the problem, as long as it's properly mixed, and
> you've made sure of that.
>
> That's no help for the images that are lost, I'm sorry.
>
> Katharine
>
>
>
> The Painted Horse wrote:
> >
> > Hi Cris, Katharine, and everyone else.
> > So, I left the my gum image in the Montana, noon day sun. After two
> > hours there was definite fading but not total clearing of the image.
> > I'm sure if I would leave it out more it would clear, and I intended to,
> > but a disaster took me off in another direction and I could use some
> > help. While testing the sun clearing of gummed images I was working on
> > another print clearing with pot metabi (3 tblspns per litre). When I
> > went to clear, the image began to lift and wash away! And this only
> > after 1 minute of clearing.
> >
> > I thought I mixed the pot metabi incorrectly so I started over with
> > another print waiting to be cleared...same results. Now, I have two
> > prints in the trash and I'm afraid to try and clear another print for
> > fear of losing more work. The strange thing is I already cleared one
> > print for over 5 minutes in the pot metabi a few days earlier with no
> > problems. Do you need to mix the pot metabi and let it stand for a
> > while? I mixed this batch and used it immediately. I could try the pot
> > metabi at 1% so it isn't as aggressive, but thought I would get some
> > input from the list before I move forward.
> > Thanks.
> >
> > Bill-
> >
> > Katharine Thayer wrote:
> > >
> > > Christina Z. Anderson wrote:
> > > >
> > >
> > > >
> > > > So you could actually just duplicate this with test strips exposed under
> > > > plain dichromate--my exposures were UV BL 5 minutes.
> > > > Chris
> > >
> > > Okay, the sun came out, and I've got a test going. I tried to stick with
> > > replicating your results as above for now, with one change. I used
> > > saturated dichromates, but rather than giving them the same exposure, I
> > > tried to expose them so the dichromate stain in the borders (I made
> > > really big borders) was the same shade of brown on both. Unfortunately I
> > > missed and exposed the ammonium too long, even though its exposure was
> > > significantly shorter than the time for the potassium. So the ammonium
> > > dichromate stain is a bit darker than the potassium dichromate stain
> > > and so any difference I see in result between the dichromates will be
> > > uninterpretable. At any rate this is really just a quick and dirty test
> > > anyway to see if I can get the same bleaching you got, even with the
> > > potassium.
> > >
> > > Too sick to do more than this today; I'll report back with my results,
> > > hopefully before you've left for APIS.
> > > kt


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