How to prepare a screen (for screen printing)

1. 
   

   Pls how long does it take for emulsion applied on screen to dry up, so that one can start exposing an image on it?

   
   


2. 
   

   How dim should the room be when applying the photo-emulsion on fresh screen?

   
   


3. 
   

   How dim should your room be, when placing the art work on the screen before exposing?