Re: Help with what I believe is a hardening issue

Yes, I have done and prints are great.
The secret is that before you apply the sizing the surface most be extremely
clean to get the gel to perfectly adhere
You can read about in Photo-Imaging by Jill Enfield.
Giovanni

----- Original Message -----
Wrom: NNYCGPKYLEJGDGVCJVTLBXFGGMEPYOQKEDOTWFAOB
To: <alt-photo-process-l@sask.usask.ca>
Sent: Friday, November 12, 2004 4:15 PM
Subject: Re: Help with what I believe is a hardening issue

> gdimase@hotmail.com wrote:
> >
> > Hi Katharine,
> > Then, how do you theoretically explain when you print gum on top of
glasss
> > or alluminum?
> > If you don't size it you can't get the image on the gum.
> > Glass and alluminum are perfectly clean without any "tooth" and you can
> > print perfectly on them, right?
>
>
> Umm, have you tried, yourself, printing on glass or aluminum? I haven't
> found it so easy, and it's my understanding that even the people who
> have mastered printing on these substrates (Galina, Keith, for two) have
> put some effort into it. They can speak for themselves, but I certainly
> wouldn't say so confidently that one can "print perfectly" on glass or
> aluminum, just like that. My understanding is that people prep the
> surface various ways, sub it with various materials, etch it, sandpaper
> it, overexpose to kingdom come (although I didn't find that helped in
> my own case) sometimes incantations, to get around the very real
> problem of no tooth on these surfaces.
>
> An example from my own recent experience that might help illustrate the
> difference between tooth and no tooth: I needed to expose gum on a
> nonporous surface, for reasons that aren't important for this
> discussion. In spite of all advice and effort, I was not able to
> reliably retain the gum on glass through the development stage (because
> of the nature of my task I couldn't sub with any chemical nor could I
> use a size) so after a couple days I gave up on glass and turned to
> mylar as a substitute. The mylar out of the package was as bad as glass,
> but I found that if I scuffed it well with sandpaper, it worked like a
> dream. What the sanding does is make scratches, hills and valleys and
> ridges in the mylar, in other words, "tooth" for the gum to hang onto.
> But if I filled up that tooth with sizing, then the mylar would again
> have difficulty hanging onto the gum.
>
> From Christopher James' section on printing gum bichromate on
> alternative surfaces: "Tooth is the surface texture of the substrate and
> is what's needed to hold onto an emulsion or image once it is printed.
> To create tooth, take your pick of a number of techniques. Acid etching
> of metal, sandblasting, steel wool, power sanding, multiple coatings of
> gloss spray paint, or any other way you can think of putting a texture
> on whatever you are using for a printing surface." Then he goes on to
> tell in detail how he creates tooth on metal plates. I don't always
> agree with Christopher James, but at least on this issue he and I seem
> to be inhabiting the same gum universe.
> Katharine Thayer
>
Received on Sat Nov 13 12:26:13 2004