Re: Adhesion

Katharine wrote:

> Etienne Garbaux wrote:
>>
>> In my previous post in this thread, I mentioned that gum bichromate, as
>> traditionally practiced, leaves unhardened gum between the hardened layers
>> and the support, so it is thought (apparently with some reason) that gum
>> depends on the physical tooth of a support --
>
> I was looking for a different post of Etienne's but in looking for it I
> glanced through this one and realized that I didn't read this part right
> the first time. The way I understand it on this reading, I don't agree
> with it.
>
> I disagree specifically with the statement that gum bichromate as
> traditionally practiced leaves unhardened gum between the hardened
> layers and the support.

Just sloppy wording on my part -- here, I was thinking of the "support" as
the bulk of the paper, with "woolly" fibers sticking up above it. You're
right, it's all part of the support. What I said, literally read,
describes the situation when gum is coated onto a support with insufficient
tooth (or insufficient porosity relative to the viscosity of the gum). Gum
as traditionally practiced works just because there are -- how did I put it
before? -- "support fibers more or less throughout the depth of the
coating." There is unhardened gum underneath the hardened gum, and the
hardened-gum image will wash off when the unhardened gum underneath it
dissolves, unless there are support fibers up through the gum layer into
the hardened part.

I'm beginning to think that a very porous support may be best for holding
highlight detail in gum prints.

Best regards,

etienne
Received on Mon Feb 21 12:18:57 2005