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Cloudy Chemistry
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? -- Another day wasted! |
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Cloudy Chemistry
"A R" wrote in message astle2.demon.co.uk... 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 |
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