From: Katharine Thayer (kthayer@pacifier.com)
Date: 05/20/01-02:23:48 AM Z
Katharine Thayer wrote:
>
> >
>
> Where reduction is completed, dichromate is trivalent,
I spoke loosely here; when it's reduced to +3 it's no longer dichromate
but some other species, mainly chromium oxide.
but since only a
> small amount of the dichromate is used in order to oxidize the gum
> sufficiently to harden it, (Kosar, 1965) most of the dichromate is still
> in the hexavalent stage. All that yellow-orange in the water is
> hexavalent. Only what's green is trivalent.
>
And as Pete said in the other thread, the process starts as soon as
exposure starts, and there will have to be, by nature of the process,
some green chromium oxide present even if you can't see it, because in
order for the gum to be oxidized, some of the dichromate must be
reduced. That much, everyone agrees on.
When you start answering your own posts, it's time to go do something
else. I've just been told I'm about to be gifted with an 8x10 Field
Camera so I'm trying to figure out what I need to learn in order to use
it when it comes.
Katharine Thayer
This archive was generated by hypermail 2b30 : 07/12/01-11:29:40 AM Z CST