Pls how long does it take for emulsion applied on screen to dry up, so that one can start exposing an image on it?
How dim should the room be when applying the photo-emulsion on fresh screen?
How dim should your room be, when placing the art work on the screen before exposing?
I'll try and answer best I can:
It all depends on the humidity and the air circulation in the room, but in a somewhat standard room, I would estimate it would take anything from 4 to 8 hours for the emulsion to dry up, depending on how much you put on. You don't need a really thick coat either, and I recommend using a plastic paint scraper to take off the excess emulsion before leaving it to dry. Emulsion should be evenly spread and there shouldnt be enough for it to "drip" if you leave it sideways or upside down. Better safe than sorry when it comes to letting it dry though, as you will make a mess on your equipment (light table being the worst) if you have drops or spots of undried emulsion.
You need to keep the screen away from any strong light and especially direct sunlight at all times before you're ready to wash out the un-hardened emulsion (after having burnt your image). The room should be about as bright as if it was candle-lit. You can put semi-transparent drapes or cloth over the lighting to adjust lighting if you don't have a dimmer.
The room should be as bright as for applying the emulsion. Of course, the best course is to have one dim-lit room in which you apply the emulsion, let the screen dry and then burn your image using your light table.
Hope this helps, and I hope you enjoy screen printing, it's hella fun once you get the hang of it!