Re: Gum hardening -- top down?

In a message dated 6/4/06 2:35:33 pm, zphoto@montana.net writes:

> Hey, but Terry,
> Looking at your website does not answer the question that I asked:
>
> I asked:
> "Are you suggesting that too much gum creates a situation wherein the
> dichromate will plummet to the surface of the paper and fall out of
> solution, or separate somehow from the pigment in suspension?  Tell me why
> you may suggest this as a reason?  What am I missing here?
>
> If it is that you are thinking my solution doesn't have enough fluid in it
> to keep the ammonium dichromate suspended, because there is too much gum
> solid, mind you I am only using 15% am di which then in my mix becomes a 7%
> solution, far below the 30% saturation point."
>
> Please, do tell...
> Chris
>
>
>

Chris

When I started gum printing as there was no one to teach me how to make gum
prints, let alone the large multi-colour prints I had in mind, I had to learn
from a lot of my own mistakes. A scientific empirical approach.

I started with pure pigment and W & N gum arabic which was about 17 Baume. I
found that if I tried to use anything thinner there was a much increased
chance of staining of the highlights. I also preferred mixing my own colours and
gum to the tone and hue I required with a palette knife on a plate and then
mixing in the dichromate. Then I was using 11% potassium dichromate and my own gum
made from gum arabic powder to consistency of. again. 17 Baume. Doing this
has meant that I have never had dichromate settling out of the mixture.

I realise that I did not intend to say 'too much gum', what I should have
said was too much dichromate and/or 'gum that is too thin'. Alternatively, you
are leaving the mixtures to stand longer than I would. There are lots of
variables.

Terry

Terry King FRPS

RPS Historical Group (Chairman)

www.hands-on-pictures.com/

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Received on Thu Apr 6 08:20:29 2006