Re: Sizing paper with gum and dichromate, was Re: glut

Hi,

thanks to all who replyed to my question. I'd like to add, Katherine showed
us a gum dichro layer that at least from the scan I've seen didn't show any
apparent color like Kees and Loris mention. Maybe she could tell us the
"secret" of getting a clear unstained gum layer. From what she said I think
it's all a question of exposure but I've been known to misinterpret her and
others writing before, thus maybe it's better to wait for her own words on
this.

Thanks again
Yves

----- Original Message -----
From: "Kees Brandenburg" <ctb@zeelandnet.nl>
To: <alt-photo-process-l@sask.usask.ca>
Sent: Thursday, December 15, 2005 9:26 AM
Subject: Sizing paper with gum and dichromate, was Re: glut

> Loris, Yves and others,
>
> I tried gum sizing too and got the same greenish stain that would not
> clear even after a long(er) disulfite bath and wash. Probably I
> overexposed. But why not standardize things a little bit more and size
> with gum and expose with your standard printing time through a clear
> sheet of printing substrate (or film). I'll give that a try this week. I
> do like my gelatin/formalin or gelatin/glyoxal sized papers but there's
> allways a different 'feel' in the first (gum on gelatin) and the
> subsequent (gum on gum) coats.
>
> -kees
>
>
>
> Loris Medici wrote:
>
> >IME, the practice of sizing with gum has the risk of dichromate staining
> >unless you expose very carefully. When I coat the paper with unpigmented
> >gum + dichromate mixture and expose it 30 secs without the negative +
> >contact printing frame combo (my normal exposure with negative and
> >contact printing frame is 360 secs / 6 mins. In other words: I expose
> >the unpigmented gum + dichromate mixture ~ 3.5 stops less when
> >sizing...), I get a slightly greenish / grayish surface (very slight and
> >subtle, but you can see it clearly), not paper white. Probably I should
> >expose less in order to get rid of the stain (or reduce it further) but
> >if I do so, I may get suspicious about the effectiveness of the sizing.
> >Therefore, I size with gelatine and harden in formalin. (BTW, I should
> >admit that: I never tried to use paper sized in that manner - I mean for
> >gum printing, I didn't like the cyanotypes I've made on paper sized with
> >gum dichromate - and dumped that method when I saw the stain + my bad
> >experience with Cyanotype... I also didn't tried to establish a
> >non-staining exposure time - I guess I was lazy back then).
> >
> >Regards,
> >Loris.
> >
> >-----Original Message-----
> >From: Yves Gauvreau [mailto:gauvreau-yves@sympatico.ca]
> >Sent: 15 Aralık 2005 Perşembe 14:31
> >To: alt-photo-process-l@sask.usask.ca
> >Subject: Re: glut
> >
> >
> >Hi,
> >
> >out of curiosity, would there be a "problem" sizing with gum instead of
> >gelatine especially if you intend to do gum printing later???
> >
> >Yves
> >
> >PS Aren't we suppose to sent our message in plain text...
> >
> >
> >
Received on Thu Dec 15 08:56:25 2005