Floating lids

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Can someone suggest a good material to make floating lids for covering b and w printing chemicals in trays. Thanks YA Sinclair

-- Yaakov Asher Sinclair (sinclair@actcom.co.il), November 29, 1999


Saran Wrap? upside down trays of same or larger size - i.e. sort of straddling the smaller tray like the interleaved boxes containing sheet film?

-- Sean yates (yatescats@yahoo.com), November 29, 1999.


-- Dave Anton (daveanton@home.com), November 29, 1999.

Sean's idea can be perfectioned using one more larger tray, flat bottom, containing about half an inch of water, in which you can place the two-trays assembly suggested by Sean. In this way, the upper tray border will dip in the external water, and will "seal" the inner tray preventing a too fast oxygen exchange with the outer air. I hope I made myself clear enough, Franco

-- Franco Rallo (f.rallo@ele.uniroma3.it), November 30, 1999.

Some more words about my suggestion, regarding a possible side-effect. The developing solution reacts with the oxygen, and this could cause the internal tray to reach a pressure lower than the exterior atmosphere. The sealing water could be pushed into the developer tray, if the solution is kept closed for long time. Check it out! Franco.

-- Franco Rallo (f.rallo@ele.uniroma3.it), November 30, 1999.

I assume you are trying to prolong the life of working strength chemicals which you have not used to their capacity such as mixed developer, etc. Of course, developers are the most susceptible to oxidation which can shorten their working life tremendously. Most manufacturers give 24hrs in an open tray as the life of working strength developers. I have on occaision used a plastic wrap laid onto the surface of the liquid and up the sides of the the tray (use two or more overlapping sheets for larger trays) when I have a large quantity of little-used developer left after a printing session. This seems to extend the working life of the developer to 48+ hours. At the first sign of discoloration, the developer is discarded and a new one mixed. Low darkroom temperatures also help to slow down the reactions which destroy developers. Stop bath is not susceptible to oxidation and requires no special handling. Kodak gives 7 days as the life of a working solution of fixing bath in an open tray. Therefore, it is probably not necessary to worry about the fix either. Keep in mind that chemicals are MUCH cheaper than paper/film, not to mention your time, so don't try to cut corners by stretching your developer, etc. past their working life. Also, keep track of your developer (not to mention fixer!) capacity and discard it when reached. Exhausted developers can have a large effect on print/negative quality! Regards, ;^D)

-- Doremus Scudder (ScudderLandreth@compuserve.com), November 30, 1999.

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