Maximum Humidity in a darkroom?

[hoffy]

Howdy,

Its been a few months since I hit my darkroom and now I want to get back into it. Unfortunately, it looks like the Southern Australian summer has a bit of a head start and at the moment, we are experiencing temperatures in the mid to high 30deg C range. The other thing of more of a concern for me is the low low humidity. Yesterday I noticed that it was down to 8% RH (& doesn't my sinuses know it!!!!).

To keep the dust levels down in my dark room, I was thinking of introducing some Humidity, whether by a humidifier or by routing some air in from our evaporative cooler. The easiest option is the Evap cooled air, but this will mean quite a lot of air movement (stirring up what ever dust has settled.). My concern with a humidifier is too much humidity, which may cause condensation (I also haven't done too much research on these yet).

Is there a maximum humidity I should have set in the darkroom?

 

[dpurdy]

You should get a hygrometer so you can make adjustments as the humidity goes up or down. 50% is a good target. My darkroom bounces between 70% and 35% and when it gets high I run a dehumidfier. When it is as high as 70% I start to smell mildew and it takes forever for fiber based paper to air dry. It also begins to make me worry about my lenses which I then put in a dryer spot.
Dennis

 

[Rick A]

According to Kodak, the ideal RH for a darkroom is between 45-50% with a temp ranging from 70-75deg. If you plan on using the evap cooler, just keep track of the humidity in the room, and enjoy the coolness.

Rick

 

[juan]

Here in Florida, my humidity frequently exceeds 75% in summer.
juan

 

[ic-racer]

In the Northern US we get the extremes. In the winter, the usual home heating system lowers the humidity below 45% and in the summer the typical basement is gong to be well above 50%. So, I have both a humidifier and a de-humidifier. I turned the de-humidifier off about a month ago, but have not yet had to turn on the humidifier yet. Right around 50% today.

 

[hoffy]

Thanks for the advice. I think that the evap cooling will be the best method. Just need to hurry up and get that exhaust fan installed (or I will have a wickedly pressurised darkroom.)

 

[jp80874]

Besides dust, really low humidity can lead to static electricity. This can look like lightning on your negatives. This can be good or bad depending on what else you might want on your negatives.

John Powers