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

On Dec 15, 2005, at 6:46 AM, Yves Gauvreau wrote:

> 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.

Perhaps my earlier response, while true enough, was a bit tired and
discouraged, so here's a further clarification:

No, as I've said three times already in response to this repeated
misperception, I have NOT said that *the* cause of dichromate stain is
overexposure. In fact I've been careful to say that there are probably
many reasons for dichromate stain. On my own page on stain on my
website, for example, I show dichromate stain resulting from the use of
a particular Linel white gouache paint. And I've seen dichromate stain
resulting from certain combinations of paper/sizing. So no, it's not
accurate to say that I think "it's all a question of exposure," if
it's dichromate stain you're talking about.

What I did say was that in the case of the sample of dichromate stain
that I showed you, when you asked what caused the dichromate stain, I
said that *that* dichromate stain was caused by deliberate
overexposure. Within my own practice, my routine methods do not
produce stain, but gross overexposure does; if I want to produce stain
for study, I can reliably do so by overexposing the gum. But I am not
making more of it than that; I'm not saying that the reason other
people can't get clear gum is that they are overexposing their gum; I
don't think for a minute that it's so simple. I suspect it is probably
a complex interaction between more than one thing. Hope that's
finally clearer,
Katharine
Received on Thu Dec 15 15:54:48 2005