Quote Originally Posted by _tf_ View Post
[snip]

One thing about loading film in a darkroom, be weary of forgotten red lights. I have a temperature sensor and a smoke alarm in there, and these have little red lights that occasionally flash. They are not a problem for working with B&W paper, though I cover the LEDs with a bit of black tape anyway. Turns out because the plastic housings are white this is not enough to achieve complete darkness, as I only discovered the first time loading 4x5 film.
I had this problem with the controllers I use for air and tray development temperature control. Big bright 7-segment displays and white enclosures. Black plastic electrical tape is your friend here. I can even peel it back to make sure the temp is still set correctly.