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Thread: Darkroom Light Sealing and Ventilation

  1. #1

    Join Date
    Oct 2019
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    27

    Darkroom Light Sealing and Ventilation

    I was fortunate enough to move into a house with a proper darkroom in the basement. It needs a little tidying and work, but it was designed for photography. There are just a couple of minor light leaks where pipes, ducts, etc., go through the walls near the ceiling, and I'll have to seal around the door.

    I'm trying to figure out the best way to seal these off. I'd be fine working at night or closing the exterior room, but if I can just stick something in place that covers these spaces, it would ensure that no mishaps would take place. If I had a little tar paper, I could probably just cut a few sheats and duct tape it into place. Or maybe the duct tape or some cloth tape alone will do. I can probably handle the door with some stick on foam rubber that I probably already have. What do you use?

    I'm also wondering about ventilation. Is this something that is necessary, given that I'm working with chemicals? There is none in the room now. I'm sure I could work something out with an exhaust fan an some baffling to keep light from passing through. Or am I just overthinking this?

  2. #2

    Join Date
    Sep 1998
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    Oregon now (formerly Austria)
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    2,429

    Re: Darkroom Light Sealing and Ventilation

    You're not overthinking things. You really will enjoy working in your darkroom better with no light-leaks and good ventilation.

    If your light-leaks are just the holes that pipes and conduits pass through, you can make or buy trim rings for both sides of the wall. Decorative metal rings are sold at hardware stores in most sizes and many are two-piece, meaning that they can be installed easily without unhooking anything. Rings on each side of the wall secured well with adhesive or putty will do the job.

    As for the door: I have just a single interior door that leads into my darkroom. I installed a threshold (just glued it to the linoleum-over-concrete floor), adjusted the door height (planing) so that the bottom of the door just brushes the rubber seal on the threshold and then added a rubber sweep to the inside bottom of the door. Then I added compressible rubber-tube-type weatherstripping all around the door jamb. Result: total darkness; no light leaks at all. I had intended to install baffles on the inside of the door as well, but it was unnecessary. You can likely cobble up some combination of threshold and weatherstripping for your application that will work.

    Ventilation. I was lucky enough to have a hole already made in an exterior wall along with wiring, so I just had to come up with ducting and a fan (which was harder than it looked at first...). You'll have to find where you can install a fan; wiring needs to be there and you need to make sure it's lightproof somehow.

    Here's what I've done in the past: In my first darkroom, I just installed a ceiling fan above the center of the sink and vented it into the attic (dark already there) and then used a length of flexible vent hose which I looped twice and hung from one of the rafters. Easy lightproofing. I now have an in-line fan that sits on a shelf above my darkroom sink. I draws air from just above the sink through a length of 3" pvc pipe with holes drilled in it, which is hung below a shelf at the back of the sink. It was a bit of a MacGyver job to get all the parts to fit, but I managed.

    If you want an off-the-shelf solution, Doran sells lightproof fans and vents (B&H has them). You still have to have a vent hole and wiring for the fan.

    I used two of the Doran 12x12" lightproof vents for my current darkroom. I framed 12x12" boxes into the wall, which accept standard 12" furnace filters. I installed the Doran lightproof vents on the darkroom inside and a regular metal vent cover on the other side. So now, when I run the exhaust fan, filtered air is pulled in through the vents (one on an opposite wall, one on a perpendicular wall). This helps a lot with dust.

    Anyway, I recommend you find a way to install an exhaust fan over your sink or build some exhaust system along with a filtered vent or two for make-up air. It will make your life a lot easier. Also, make sure you choose a fan that is quiet! Noisy fans are a real PITA.

    FWIW, I don't run my fan all the time, but it's sure nice to have.

    Hope this helps,

    Doremus

  3. #3
    Eric Woodbury
    Join Date
    Dec 2003
    Posts
    1,362

    Re: Darkroom Light Sealing and Ventilation

    Much the same here. One darkroom vent in the door and an exhaust fan in the ceiling that I bought from Grainger. Best thing to do for fresh air is to avoid smelly chemicals. I use citric acid for paper stop (I used only water for 50 years, but the paper I'm using seems to demand a good stop). I use rapid fix without hardener as I think the hardener stinks. Most of the time, the fan need not be running.

    A visit to the hardware store will show you a host of door weather stripping that blocks light. Everything else is drywall (sheetrock).

    Not in your question, but here you go anyways, my floor is concrete slab. It would control the temperature in the darkroom for better or worse, but I covered it with cork and covered this with real linoleum. It's a comfortable floor. 9x12' room is heated by a small space heater.

  4. #4
    Les
    Join Date
    Dec 2011
    Location
    Seattle, WA
    Posts
    1,085

    Re: Darkroom Light Sealing and Ventilation

    You could hang a large piece of material (dark/blk) covering the entire door all the way to floor. You don't want to be freaking out when you see a car turning nearby and you could see the lights under or near the door. If I were you I'd do a permanent fix (finished wall) with everything in place: fresh door trim, door seal, baseboard, etc. preventing any leaks....or at least make them manageable with a towel. Cross ventilation will help a lot. I do like Ken's solution of installing funnel for fan/s right over the trays.

    Les

  5. #5

    Join Date
    Oct 2019
    Posts
    27

    Re: Darkroom Light Sealing and Ventilation

    Those Doran fans are expensive, particularly compared to light-tight louvers. That has to be some way I can improvise something combining a standard bathroom vent with the louvers and a small duct.

  6. #6

    Join Date
    May 2007
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    New York City & Pontremoli, Italy
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    Re: Darkroom Light Sealing and Ventilation

    Quote Originally Posted by alt.kafka View Post
    Those Doran fans are expensive, particularly compared to light-tight louvers. That has to be some way I can improvise something combining a standard bathroom vent with the louvers and a small duct.
    Where are you?

    I have a Panasonic Whisperline fan that I thought I was going to use in my darkroom build (I built a different ventilation system that’s at tray level instead). It is very powerful and not too noisy.
    I no longer have the box (very large) - if you can pick it up, it’s yours.
    I am in NYC.

  7. #7

    Join Date
    Oct 2019
    Posts
    27

    Re: Darkroom Light Sealing and Ventilation

    Quote Originally Posted by Renato Tonelli View Post
    Where are you?

    I have a Panasonic Whisperline fan that I thought I was going to use in my darkroom build (I built a different ventilation system that’s at tray level instead). It is very powerful and not too noisy.
    I no longer have the box (very large) - if you can pick it up, it’s yours.
    I am in NYC.
    Thank you for the offer. That's very generous of you. I'm just outside of DC, so I'm afraid it wouldn't be possible. That does look like a good unit, though.

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