Re: Gelatine is also '' a '' gum but not Gum.

In a message dated 5/4/06 12:51:24 am, jseigel@panix.com writes:

> Actually, the distinction generally given in "the literature" is that
> because carbon hardens from the top down, transfer is necessary (although
> "direct carbon" without transfer has its own litany), while gum (as far as
> has been established to date) hardens at the surface of the paper.
>
>

Judy

I must agree with Sandy although Sandy's reply disappeared from my screen,

In all my experience of making gum prints and carbon prints for printing and
gravure, the coating hardens from the top down. But then I believe that it one
should use as few coatings as possible to achieve one's effect rather than
building up the contrast with many layers. If one uses very thin layers one may
not be able to tell the difference between hardening at the surface and
otherwise.

It may also be significant that using the Autochrome tissue, I have no
trouble in clearing highlights in carbon prints. But that is on fixed out RC paper.
A couple of years ago. after many years of practice, the tissue stopped
transferring effectively to home made transfer paper made following a recipe that I
had used for many years. We are now conducting a further trial with Dick
Sullivan's tissue.

It all shows how inadvisable it is to place too much faith in manuals.

Terry
Received on Wed Apr 5 02:53:42 2006