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What cause black silver deposit on negative during fixing


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<p>If your dots are really metallic silver (doubtful) they would have to be exceedingly small, on the order of 3 microns or smaller. You'd only see them with a lot of enlargement; you wouldn't see them with the naked eye.</p>

<p>The only place in the development chain to get metallic silver IIRC is from fixer that's been reused enough to saturate with silver, such that some silver precipitates out. The cure for this is to not reuse your fixer when developing film.</p>

<p>All that said, it's unlikely that your black spots are metallic silver. It's likely crud from some other source. Film processing is a never ending fight for cleanliness. It's a fight you have to wage, but can never win.</p>

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<p>I filter my fixer through a coffee filter in a funnel after each use. This has ended the redeposited silver one gets without filtering reused fixer.</p>

<p>A good routine for cleaning and storing processing equipment will eliminate all contaminates. </p>

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<p>I have had rapid fixer silver plate bottles. I believe it does this when the pH is wrong. </p>

<p>I have not seen an effect on film, but then I don't use it when it gets to that point.</p>

<p>Some day I will get a pH meter, and test it.</p>

-- glen

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<p>It is due primarily to the fixer becoming saturated with silver. From my own experience I suspect it may also be due in part to the progressive exhaustion of the stop and its loss of acidity. I filter my fixer at intervals through a coffee filter.</p>
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<p>Fix is so cheap, it is not worth reusing it. I never do anyway. If I'm doing a few films together then I'll just use the same fix all day and extend the time by 10% each time, and that seems to work. I have films going back to the Seventies and none of them has faded yet.</p>
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<p>I was plagued with spots, more so, using a scanner.<br>

I filter everything before use, using coffee filters and after, as I pour back into solutions.<br>

I use new plastic bottles whenever I prepare new solutions of fixer and stop bath.<br>

I keep the Canon scanner covered all the time, except while in use.</p>

 

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