Film Safelight query

[phigmov]

I've seen a safelight for sale and I'm interested in it for a lab.

I've seen these in use in tv shows & films but the description on Wikipedia is a little vague - references their use in the development process but it seems to focus a little more on developing prints.

Can these be used at all stages of the development process including the start ?
Eg can you use it while removing used film from a canister or unspooling a roll into a development tank ?

 

[Carbonman]

Safelights are only for printing B&W film. Regular black & white printing paper isn't sensitive to the red color but our eyes are. All film and color photo paper are sensitive to this light, so you can only use a safelight when doing your B&W enlargements.
You need to have your film in total darkness when opening the cassette or spooling your exposed but undeveloped film onto the processing reel. It's a little disconcerting when you start but becomes second nature after a few rolls. I used to find working in total darkness quite relaxing; I was able to visualize where everything was and it forced me to develop methodical habits.
When you're printing color, the illuminated gradations of each color in the enlarger head dials are easy to see with the naked eye; it doesn't have any impact on the paper. The total light output was negligible.

 

[phigmov]

Thanks @Graham Moore - appreciate the insight. Just as well I double-checked