Darkroom ventiation

[Bob Passage]

Due to construction logistics I have built the ventilation system of my darkroom at one end of my 8' sink. The air supply intake is one the opposite wall. My thinking was to pull the vapors rising from trays away from my face. I use PMK developer and TF-4 fixer. The question is: Which vapors are more intense and should be placed under the vent? Although the vent is more than adequate for the cubic feet served, I would prefer to evacuate the more toxic fumes first. Thanks

[Philippe Gauthier]

I doubt that either emits much toxic fumes, once in liquid form (PMK in powder form is another thing). Even the fix is essential weak vinegar (about 2% acetic acid). The spot nearest to the vent will be most useful for your sepia toner (which emits small amounts of toxic hydrogen sulfide gas), or when manipulating chemicals powders.

[Bruce Watson]

What Philippe said.

[Bob._3483]

For the life of me, I don't know why people still use acetic acid: switch to citric acid and you can stick your nose an inch away from it and take a double lungfull - just smells slightly sweet. Of course, some people prefer just water. Add a low-odour fixer (almost as devoid of pong as the citric acid) and the worst of the fumes are history, leaving only the developer.

I don't know how much PMK pongs tho' as I use ID-11 in a Jobo. My main exposure is when printing, where the low-odour stop and fix are very effective at improving air quality.

Cheers,

[David Vickery]

Hey Bob, that first part is what I was going to say! Citric Acid is great!

But I don't use much of it when I process film, (no acid at all, except a little of the Citric) or if I still did use acetic acid, and if I had thought about it enough when I built my darkroom I would have put the fan at the inlet side inside instead of at the outlet so that I would have a positive pressure in the room which will help to lessen the fumes.