Darkroom Humiditi

klop · Apr 10, 2015

My dehumidifier set at 35% keeps my darkroom at between 40% and 45%..... Is this a good range?

klop · Apr 10, 2015

It was supposed to be humidity... Sorry.....

ParkerSmithPhoto · Apr 10, 2015

40-60% is usually very comfortable. It's pretty obvious if it gets too low as you'll get a static spark every time you touch the door knob.

Photo Engineer · Apr 10, 2015

50% RH is the Kodak gold standard for its darkrooms.

PE

Bob Carnie · Apr 10, 2015

plus one- its also best for paper and mounting.

Photo Engineer said:
50% RH is the Kodak gold standard for its darkrooms.

PE

Ken Nadvornick · Apr 10, 2015

My dehumidifier is set to 50%, except when processing film. Then the unit is turned off.

When processing is complete I do a final sink rinse with hot water, which leaves small puddles. I then hang the wet film over the sink (and puddles) and exit the darkroom. The residual warm water slowly evaporates under the hanging film. Drying takes longer, but my negatives are always perfectly flat.

Next morning I restart the dehumidifier at 50%.

Ken

pentaxuser · Apr 10, 2015

My darkroom is in my house and assuming my relative humidity gauge is correct my house's RH might get as low as 60% in a very long hot dry spell of the kind we get every 50 or so years in the U.K.

I have never noticed any problem with an RH in the mid to upper 60s range so the good news is that you might get by with a much higher RH.

Perhaps my fellow U.K. APUGers will respond with their readings

I had forgotten that most of you guys live in the Sahara Desert or its equivalent

pentaxuser

ParkerSmithPhoto · Apr 10, 2015

If you set it at 65%, you can also use your darkroom as a humidor.

nworth · Apr 11, 2015

I have the opposite problem, and I have to run a humidifier sometimes. For most silver gelatin photography, humidity is not terribly critical. Any level where you are comfortable will do nicely. Low humidity sometimes leads to problems with static electricity and with film curl. High humidity can encourage mold and mildew. 50% is great if you can get it. When I do alternative process work, which is critical about humidity, I sometimes have to run the humidifier for a couple of days to get the humidity up to an acceptable 45 percent. Once there, it is pretty easy to maintain.

Jim Noel · Apr 11, 2015

ParkerSmithPhoto said:
If you set it at 65%, you can also use your darkroom as a humidor.

ANd have a better atmosphere for printing most alt processes.

DREW WILEY · Apr 13, 2015

Humidity is good for controlling static but bad for equipment, drymounting, and supplies like film, paper, and matboard. Most of the time it's
foggy around here anyway. I have the luxury of several different rooms, each of which can be managed separately with respect to climate
control.

Bob Carnie · Apr 14, 2015

Drew- a very strong expresso each morning will clear up the fog... that fog may explain a lot of your posts.

Paul Howell · Apr 14, 2015

This time of year in the Desert Southwest our humidity runs from 3% to maybe 20% on a muggy day. My darkroom is built in a bathroom, well I don't have bath just a shower, so I fun the shower for a minuet or so to bring the humidity up to help settle the dust. During the summer monsoon our humidity can climb to 70% but the heat pump acts live a dehumidifier.

DREW WILEY · Apr 14, 2015

Bob - never mind all my typos. I explain to all my customers that I am essentially senile without at least four cups of coffee in me. Somehow I manage to negotiate the freeway chaos and get here with only one cup in me. But even geese can commute long distances, and they aren't all that bright either. So maybe that part is instinctive by now. But I want rich coffee, not jolt coffee; my stomach won't handle that. If I did want concrete etch I could just visit the coffee pot down the hall. That stuff does taste good too, but will pop your eyeballs out. So I bring my
own.

Darkroom Humiditi

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