Mike Ware's hypothesis, as I understand it, supposes a special
affinity of dichromate for paper, resulting in an attraction of the
dichromate to the paper. I assume that if his theory were correct,
the dichromate would "gravitate" to the paper even if the paper were
placed upside down so that the paper is above the coating layer.
If the dichromate simply separates and moves faster down through the
layer because of its different (weight, density, viscosity, mobility,
whatever you want to call it) as Chris seems to be suggesting (and
for the record, I've observed something similar at the end of brush
strokes) the effect would probably be similar, but it would be a
different hypothesis.
At any rate, for whatever it's worth, Jeremy, I think it's the other
way around. If you leave a coating mix sitting in a dish, you'll
usually find (at least I find) the pigment settling to the bottom
and needing to be stirred back in before coating, rather than the
dichromate settling to the bottom. But it may behave differently
when it's a film.
Katharine
On Apr 5, 2006, at 10:19 AM, Jeremy Moore wrote:
> I would think that if the relative density of the dichromate is
> much higher than the other chemicals in the solution you would see
> a definite sinking. This happens very quickly in solution. Then
> again, I have no idea what the relative densities are of the
> chemicals in the solutions so take with a grain of salt.
>
> -Jeremy who knows naught of science
Received on Wed Apr 5 11:48:36 2006
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