Re: clearing dichro stain with sulphuric acid was Re: (Gum) Tonal scale

From: Yves Gauvreau ^lt;gauvreau-yves@sympatico.ca>
Date: 12/09/05-08:36:10 AM Z
Message-id: <07cc01c5fccd$e6804b70$0100a8c0@BERTHA>

Thanks Pete,

I should have said it earlier, I search the archive and I have found that
tests where made (by you maybe) and showed sulphuric acid clearing to have
only 0.05 residual density and as you say below some light grey tint is
left.

All this makes me wonder how all of these invisible little molecules will
affect the permanence and stability of gum prints... There getting farther
and farther from those cavern paintings every time I think about it.

Regards
Yves

----- Original Message -----
From: "peter" <temperaprint@blueyonder.co.uk>
To: <alt-photo-process-l@sask.usask.ca>
Sent: Friday, December 09, 2005 8:24 AM
Subject: Re: clearing dichro stain with sulphuric acid was Re: (Gum) Tonal
scale

> Yves,
>
> I think there is always a stain, The stain left by the sulphuric acid
> is not heavy is but a light grey in colour you will need to have a
> heavy brown oxidised stain intialy to be aware of it.I find it very
> useful in maintaing Tricolour balance
>
> Pete back from he
>
>
>
>
>
>
>
> On 7 Dec 2005, at 09:23, Yves Gauvreau wrote:
>
> > Pete et all,
> >
> > I don't know if you saw Katharine experiment (link below) or not but
> > the
> > reason I ask the question was to find out if the one(1%) solution of
> > sulphuric acid you've been using all these years would leave a
> > noticable
> > tone like the NaCl and the other stuff did leave???
> >
> > Yves
> >
> >
> > ----- Original Message -----
> > From: "peter" <temperaprint@blueyonder.co.uk>
> > To: <alt-photo-process-l@sask.usask.ca>
> > Sent: Tuesday, December 06, 2005 9:35 AM
> > Subject: Re: (Gum) Tonal scale
> >
> >
> >> Dear Yves.
> >>
> >> I have used a one(1%) solution of sulphuric acid to clear the brown
> >> dichro stain for the past twenty years with no ill effect in both Gum
> >> and Temperaprint.
> >>
> >> Best wishes
> >>
> >> Pete
> >>
> >>
> >>
> >>
> >> On 6 Dec 2005, at 00:38, Yves Gauvreau wrote:
> >>
> >>> These are very interesting results Katharine, thanks for sharing them
> >>> with
> >>> us.
> >>>
> >>> I ear that some acid (sulfuric acid maybe) could help to clear the
> >>> dichromate, I'd be curious to see or ear about a similar test using
> >>> it???
> >>>
> >>> Thanks
> >>> Yves
> >>>
> >>>
> >>>
> >>> ----- Original Message -----
> >>> From: "Katharine Thayer" <kthayer@pacifier.com>
> >>> To: "alt photo" <alt-photo-process-l@sask.usask.ca>
> >>> Sent: Sunday, December 04, 2005 9:50 AM
> >>> Subject: Re: (Gum) Tonal scale
> >>>
> >>>
> >>>> I accidently sent this to myself instead of to the list, (still
> >>>> figuring out my new mail program) so I'm sending it again, to you.
> >>>>
> >>>> On Dec 3, 2005, at 1:00 PM, Katharine Thayer wrote:
> >>>>
> >>>>>
> >>>>> After I wrote that about dichromate stain, I remembered that I
> >>>>> have a
> >>>>> page showing the color of unstained gum, of dichromate-stained, and
> >>>>> of
> >>>>> cleared stained gum, on my site; here it is if anyone is
> >>>>> interested:
> >>>>>
> >>>>> http://www.pacifier.com/~kthayer/html/gumcolors.html
> >>>>>
> >>>>> The samples don't show different tones, because it was gum that
> >>>>> was
> >>>>> exposed without a step tablet or any kind of negative, just
> >>>>> hardened
> >>>>> gum. that's when I was working on that project of making gum for
> >>>>> chemical analysis.
> >>>>> kt
> >>>>>
> >>>>
> >>>
> >>>
> >
> >
>
Received on Fri Dec 9 08:38:37 2005

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