"A R" <news@[EMAIL PROTECTED]
> wrote in
message
news:1idlnsq.1lacdek18ltsh0N%news@[EMAIL PROTECTED]
>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@[EMAIL PROTECTED]
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