Wayde Allen (wallen@boulder.nist.gov)
Fri, 15 Jan 1999 09:24:39 -0700 (MST)
On Thu, 14 Jan 1999 FotoDave@aol.com wrote:
> > Is this
> > kind of a muddy film? I've seen this happen in my dichromate solutions,
> > and mine aren't mixed to saturation. It sounds like there was something
> > in the water that is reacting with the dichromate.
>
> Kind of hard to describe. It is brown and yes, I guess it's muddy, and it
> sticks to the bottom of the bottle, that is, even when you shake the bottle,
> it remains there.
That is what I thought. I don't think you are precipitating dichromate
out of the saturated solution. If you were, you should be seeing
dicrhomate crystals, and these should redisolve when you increase the
temperature. I think you what you are seeing is the byproduct of
something that the dichromate solution is oxidizing.
> > It was mixed up
> > shortly after the first issue of the Post Factory Journal arrived, and I
> > don't think that there is any precipitate in this bottle - yet anyway.
> > I'll have to check.
Still haven't had a chance to check my bottle, but I don't remember
noticing any sludge when I used it earlier this week.
> Hmmm.... does the fact that I store it in a plastic bottle instead of glass
> bottle matter? It is stored in a plastic bottle that was for photo chemical.
I don't know. I suppose that it is possible you are getting some reaction
with the plastic. Probably the easiest way to test this would be clean
your plastic bottle, mix a new dicromate solution, store part of the
new solution in a glass bottle, and the rest in your plastic bottle. If
the sludge forms in the plastic bottle and not the glass one, you would
have some indication that the plastic is reacting.
I have been storing my solution in a brown glass bottle equiped with a
glass eye dropper in the lid. They sell these at the local health food
stores for about $0.60, and the eye dropper is handy for measuring
out the solution.
- Wayde
(wallen@boulder.nist.gov)
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