From: Katharine Thayer (kthayer@pacifier.com)
Date: 05/12/01-01:19:41 AM Z
Peter Fredrik wrote:
>
The
> dichromate processes are in fact governed by the effects of oxidation this is the
> mechanism that produces the tanning effect. The greater the exposure the greater
> the oxide present. I suspect that the oxide is always present after exposure, even
> though in small quantities it is invisible
Sorry, I thought I was done with this, but this above isn't making sense
to me. Yes, there is an oxidation process going on, but the way I've
always understood it, it's the colloid that's being
oxidized, hardened, "tanned", not the dichromate (and for that matter,
it was always my understanding that "tanning" in this case means
hardening, rather than changing color). The chromium compound, if I
remember my chemistry right, which of course is a big If, is being
reduced rather than oxidized, which makes intuitive sense because in its
original, hexavalent state, it has plenty of oxygen to give up. I need
to see the chemical equations that govern this process, if someone would
be so kind, so I can picture what's going on here... Thanks...
Katharine Thayer
This archive was generated by hypermail 2b30 : 07/12/01-11:29:39 AM Z CST