 Re: Please help. Exposure time.
There is not single chart which will tell you the exposure time you need to be using.
The issue is, everybody had a different setup. Emulsions have different exposure times. Brand "A" may expose twice as fast as brand "B". The exposure unit also greatly effects effects the exposure speed.
My guess is that you have 2 things going on. One an exposure problem and the second a film/contact issue.
Given a "perfect" film and exposure combination, over exposure would be impossible.
Next time you expose a screen, add a piece of aluminum foil and black electrical tape to the film being exposed. Aluminum foil is 100% opaque. No matter how long you expose the screen, the mesh under the foil will never get exposed. The electrical tape is similar to the foil in the inability to pass light, but also is sticky and will hold directly onto the mesh. When you wash out the mesh, see if the foil and tape behave differently than the film.
Most emulsions have a color change which happens during exposure. Great exposures happen with a surprisingly little color change.
fred
__________________
A day late, a dollar short, so it goes.
| 
