Re: Could someone summarize that gum up or down discussion?

On Apr 13, 2006, at 8:26 PM, Christina Z. Anderson wrote:
>

>> Judy and Chris mentioned the fact that unreacted dichromate
>> leaves the print very rapidly, as an observation supporting
>> bottom hardening, but I don't see bottom hardening as a necessary
>> conclusion from the observation. The hardened gum matrix is a net
>> rather than a solid slab, and the dichromate can easily slip
>> through the net, at least that's the way it was explained to me
>> by a physical chemist. So the observation that the dichromate
>> runs out easily is neither here nor there as far as which way gum
>> hardens, IMO.
>>
>
>
> Whhhhoooooaaa leave me out of this. In fact, all I said was a "this
> is verrrrry interesting" remark when you, Katharine, mentioned
> Mike Ware's theory of bottoms up, by remarking that sometimes I
> observe when brushing on a layer the dichromate seems to be
> separate and at the bottom of the brushed swathe.
>

Chris, it was the below sequence that I was going by, not the part
about the dichromate separating from the pigment/gum during coating
that you refer to above. I read that sentence (below) to mean that
you were agreeing with Judy on that point; apparently I was mistaken.

Katharine

On Apr 6, 2006, at 8:34 PM, Judy Seigel wrote:
>
> I'm going to mention two observations that suggest to me that
> hardening in gum isn't top down.
>
> First is the fact that most of the unexposed dichromate seems to
> come out of the print in the first 10 minutes (in fact some manuals
> point that out & instruct accordingly).

On Apr 8, 2006, at 8:59 AM, Christina Z. Anderson wrote:
>
>
> In reference to Judy's post, too, I find it odd that dichromate,
> when you place an exposed print in water to develop, immediately
> leaches out of the print in the first 30 seconds.
Received on Thu Apr 13 22:59:34 2006