I'm turning my basement into a darkroom and I gotta cover up the windows. I plan on going to Home Depot and picking up some black landscaping polyurethane on a roll. 5mil thickness should be good enough for windows, so it would definitely be sufficient for covering up a door, and it's rather inexpensive too.

I have a feeling that the light would come through the plastic. In one of my darkrooms in a wine cellar I built a light trap for my window so I'd have some ventilation. The plastic I tried first let light in.

[ytterbium]

So a closer look at the door revealed that the situation is even better for most edges except at floor. There is a double step-like structure.

Now i might take an ultra bright flash light and check some insulation/sealing materials at store, but i wonder where would be the best place to install them (depending on their shape of course).

Theoretically the more the best, but im afraid that extensive modification might not let the doors close.
Another problem is floor. There is no step-like structure at all. See illustration.

You most likely could get away with weatherstripping on the jambs. It would neet to be snug so that the door would need to be pulled closed. As for the floor a strip of weatherstrip attached with velcro should work. The velcro would allow removal when not used as a darkroom and you wouldn't scratch the floor with constant opening and closing.

If you do that and still see a couple leaks you could get some heavy black fabric and velcro it to the inside of the jamb also. The fabric can't be all that expensive. Just make sure it has some thickness to it.

[Wheatfield]

I have a feeling that the light would come through the plastic. In one of my darkrooms in a wine cellar I built a light trap for my window so I'd have some ventilation. The plastic I tried first let light in.

That plastic often transmits IR light. Aluminium foil is the best way that I know of to light proof a window.

[photog]

You wrote"Btw. some people have told me that you cannot work with B&W film under red light, because most current films are sensitive to it.
Is this true for B&W as well?
How do you make prints then, or is the paper still insensitive ?"
B&W film is termed "panchromatic" that is sensitive to light of all colours and should be processed in total darkness. However since you will be using some sort of film tank it is merely necessary to load the film in the dark. The processing can be carried out under normal room light. Some have in emergency climbed in under the blankets to load tank!
Paper on the other hand is not sensitive to light fron the yellow to red portion, is nowhere near as fast as colour film and can be processed under a bright amber safelight. Colour film is sensitive to all colours and is in any case usually machine processed as temperature control is very critical (+- .5C or less)
After processing many tens, perhaps hunderds of negs and prints in everything from sou plates to high-speed continuous machines, I am now happy to shoot digital and "develop" in Adobe LIGHTroom.

That plastic often transmits IR light. Aluminium foil is the best way that I know of to light proof a window.

Aluminum foil? Every darkroom I've ever been in/worked in was light proofed with black materials. Or is you jest jesting?

[buliwyf]

its hard to 100% lightleak-proof a room. We have a studio with rotating cylinder-type door for the darkroom and it still got some leaks!

If you just want to process some b&w film, I find using a changing bag to be more convenient. I do it in the kitchen while chatting with family. Or in the living room while watching TV (then take the loaded canister to the kitchen sink for processing). The darkroom, I use for printing only. I also don't like the stop-bath smell of darkrooms hehe.

For color film, I go to mall and have them processed in one of those photo stores.

*sigh* the convenience of digital. Although black & white film prints are FAR superior from photo paper inkjet prints.

[PeteyJ]

I have a feeling that the light would come through the plastic. In one of my darkrooms in a wine cellar I built a light trap for my window so I'd have some ventilation. The plastic I tried first let light in.

What thickness were you using? Some threads I've seen on photo.net say I should be fine if I use a thickness of at least 5 mil. Worse comes to worse I can probably just double it up, or even put a piece of cardboard between the window and the plastic.

[Wheatfield]

Aluminum foil? Every darkroom I've ever been in/worked in was light proofed with black materials. Or is you jest jesting?

Nope, I'm quite serious.
My last darkroom had a window. It was a sliding aluminum window on the outside with a top hinged window inside.
I took the glass out of the inside window and put 1/4 inch plywood in it's place, and then installed good fitting weather strip.
It still leaked, and as it was right beside my dark area, I had to fix it. My solution was to tape aluminium foil to the back of the outside window.
Not only was that the cure, it was incredibly efficient at cutting light on it's own.
A person would still want to hang something to kill reflection off the foil, but it wouldn't have to be as efficient a light barrier.

[stevebrot]

As noted in the earlier comments, it is extremely important to have absolute darkness when handling most films. Ditto for color print papers.

I currently don't have a darkroom as such, though I do process my own B&W negatives. As noted above, it is extremely important that your work area be as dark as possible when loading the film reels to put in the processing tank. Interestingly, I don't have any weather stripping or similar stuff on the door to the room I use for film loading. What I do is to wait until it is the dead of night, shut off all the lights in the house, and close the door for the room that I use. The combination of dark house and shut door creates a suitably dark space. It also helps that I live alone with little chance that anyone is going to come along and flip on the light in the hallway.

Steve

(Have to remember to take my watch off...luminous dial...)

What thickness were you using? Some threads I've seen on photo.net say I should be fine if I use a thickness of at least 5 mil. Worse comes to worse I can probably just double it up, or even put a piece of cardboard between the window and the plastic.

No idea on the thickness. It was 30 years ago after all. For windows I usually build light traps. Painted black. Never had a problem even with high iso specialty films. Doors usually got some flaps over the sides, top, bottom. Sometimes leather, sometimes not. Depended on what was around.

[stevebrot]

Nope, I'm quite serious.
My last darkroom had a window. It was a sliding aluminum window on the outside with a top hinged window inside.
I took the glass out of the inside window and put 1/4 inch plywood in it's place, and then installed good fitting weather strip.
It still leaked, and as it was right beside my dark area, I had to fix it. My solution was to tape aluminium foil to the back of the outside window.
Not only was that the cure, it was incredibly efficient at cutting light on it's own.
A person would still want to hang something to kill reflection off the foil, but it wouldn't have to be as efficient a light barrier.

As a former graveyard shift worker, I can vouch for the aluminum foil trick. It forms a very nice light barrier.

In regards to the comment regarding black darkrooms...I have worked in both black and white painted rooms. Both should work equally well from a processing point of view. Ironically, a white painted space has several advantages. The first is that any stray light is more apparent. The second and more important is that white walls make for a much brighter environment for B&W printing using an OC safelight. Much nicer.

Steve

[Lowell Goudge]

Are there any special measures and materials available to seal a room completely off the light, or simple solid doors are enough.

The only room i could use for film processing basically has no direct source of stray light (windows, keyholes, doors with gap to frame) BUT....

After checking the room for 5 minutes staring in complete blackness, your eyes start to adapt and you see that the step-like door frame still is able to leak light.
If i pack the perimeter of doors with paper, i can start to see a fain fuzzy glow around the doors after 30 minutes.

How do you determine if the "darkness" level is enough for film processing.

when I had my dark room It was a closet (6 x 9 feet) inside my laundry room. I blocked off the windows and doors for the laundry room, and turned off the lights in it first, and then also sealed the closet door on the closet. This was basically achieved by a series of steps in the door frame, each painted flat black and gasketted on the ones parallel to the door. I was totally blind even after 20 minutes

Btw. some people have told me that you cannot work with B&W film under red light, because most current films are sensitive to it.
Is this true for B&W as well?
How do you make prints then, or is the paper still insensitive ?

it is OK to work under a safe light for prints but not the negatives, (remember prints can take minutes of exposure under the enlarger illumination) but you have to process them totally in the dark. THis means that they get loaded onto the film reels in total darkness. Once in the developing tank, this is light tight due to internall baffels in the lid and you can turn the lights on at that point.

[Ratmagiclady]

As for that door, I suggest just using a door sweep like you usually screw to an exterior door: some'll have a rubber flap that's a good inch or more tall: Within the jamb,some foam tape type wealherstrip, placed so it pinches ought to fit, (it'll keep it from wanting to rub every time you open or close the door, and ought to make it as tight as can be)

[PeteyJ]

No idea on the thickness. It was 30 years ago after all. For windows I usually build light traps. Painted black. Never had a problem even with high iso specialty films. Doors usually got some flaps over the sides, top, bottom. Sometimes leather, sometimes not. Depended on what was around.

If I had the tools and resources, I would most definitely build light traps around the windows. It seems easy enough, it's just that without the proper tools, there's not a whole lot I can do.