Re: Cloudy Chemistry


"A R" <news@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx> wrote in
message
news:1idlnsq.1lacdek18ltsh0N%news@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
I have two litres of Bromophen stock solution. It was made
a fortnight
ago but has since developed a white sediment at the
bottom. Shaking the
bottle causes the stock to go cloudy.

This weekend I mixed Barry Thornton's two-bath developer.
Having never
mixed my own chemistry from scratch, I wasn't sure what to
expect. The
metol proved difficult to dissolve despite warming the
water and shaking
the bottle quite vigorously -- the metol formed a
suspension in the
sodium sulphite/water solution and had a tendency to
clump.

A sediment forms at the bottom of Bath A, when left, and
turns cloudy
when shaken.

I have developed two rolls of 35mm in the two bath. The
first roll
turned out okay, but the second turned out thin to the
point of being
almost clear.

The Bromophen has turned out good prints thus far.

The solutions have been stored in a dim room at room
temperature in
clear, plastic drinks bottles with the air squashed out.

Are these sediments a good sign? Are they normal? How
should I deal with
them? Could the thin negs be a result of the sediment (the
second reel
was left in Bath A a minute less than the first)? Should
the metol
dissolve fully?



--

About Metol, I has difficulty dissolving in a solution
of sodium sulfite. You will notice that most formulas using
it have you dissolve the metol first, then the sulfite.
While the sulfite is there partly to protect the Metol and
other developing agents from oxidation it really isn't
necessary for the few minutes it takes to dissolve the
Metol. To minimize the amount of oxidation boil the water to
be used for about three minutes and let it sit and cool
before use. The boiling will drive off most of the dissolved
gasses.
I am not sure about the sediment. It may be undissolved
chemicals or it may be something in the water. Most packaged
chemistry has sequestering agents in it to deal wtih the
salts in hard water and to some degree with dissolved metals
such as traces of iron compounds. It may be that your tap
water has an unusual amount of something in it. You can use
distilled water but grocery store distilled water is
expensive and not always very pure. Another way is to use an
activated charcoal filter, like a Brita filter, and then
boil the water. This will eliminate most hardness and
metallic ions. The water may also just be dirty, if so, the
filter and boiling will remove most of it.
If the developers work normally I would just filter
them. Coffee filters work fine.
Sometimes a little rubbing alcohol dissolved in the
water will help the chemistry to dissolve. Perhaps 30ml (an
ounce) in a liter (quart) of water.
When mixing from scratch it sometimes helps to dissolve
the separate ingredients in a portion of water and then add
together the liquids.


--
---
Richard Knoppow
Los Angeles, CA, USA
dickburk@xxxxxxxxxxxxx


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