Testing Your Darkroom's Darkness

[ckpj99]

Hey folks,

Do you any of do any actual testing of your darkroom's darkness? Like leaving film or paper out for a long period of time or some other test.

Just curious.

[Ironage]

I would but the light leaks are too obvious! I just work fast

[vinny]

my darkmeter goes to 11 in mine. that's dark enough.
if you can't see your hand, it's pretty dark

[ckpj99]

To my eyes, my darkroom is completely blacked out. That being said, I'm going to tray develop some 4x5 film this week, and I'd rather not screw it up.

[Heroique]

Normally, I would trust my dark-adjusted eyes after a few minutes, but the monsters and phantoms I start seeing affect my judgment.

[lenser]

I wouldn't exactly trust my eyes based on the simple situation that when I go to bed, it is total darkness in the room, but if I get up for a bathroom break a few hours later, I can see everything I need to find my way around without any light source except the night sky outside the window. The cones and rods apparently pick up lots of night light after that rest period. Film and paper don't have that lag time, so what your eyes don't see may still be plenty of light to fog film or prints. Do the test!

[wallrat]

If you are concerned about film or paper fogging, you can do a very simple test. Leave fim or paper out in you darkroom for the longest possible time you would be working with it, then maybe double that time for good measure. When you have reached that point develop the test piece along with a sheet that has been in a protective box or paper safe in the same developer, same time, agitation, etc. Compare the results.

[Dan Henderson]

I recently changed from daylight tank to open tray development. After 10 minutes in the "dark" I was surprised by the amount of light leaking in. So off to Lowe's I went to buy several tubes of black caulk and foam door insulation, which, along with some torn chunks of black foam pipe insulation, has eliminated probably 95% of the infiltration.

I am still somewhat concerned about tray development of infrared film with the very small amount of light leakage remaining, along with a few bits of luminescent tape. I am wondering how dark is dark enough for IR film?

[ckpj99]

I've sat in the complete dark in my room for over 10 minutes. I can't see anything. I think I'm just going to load my film in a dark bag, and then try the tray developing. That should eliminate one variable. If the film looks good after that, I'll try loading my carriers in the room.

[Bill Burk]

I'd leave a piece of 400 speed film for an hour in the darkroom with a step wedge over it under glass.

Using this test with my IR scope aimed directly at the film, I came to the conclusion that I could work for 15 minutes with the scope on with no measurable effect.

You could quantify how dark your darkroom is the same way.