Hello all, I have a homemade set up with a 500 watt halogen raised 18"s above my tabletop. I am using Ulano QTX Emulsion and was burning a 110 mesh screen for 12 and a half minutes. I burned 2 of the 110 screens successfully.
Then I bought a 156 mesh screen and go through the same process. 1st, I coat the screen then dry it. The next day I expose it for the same time, and the text comes out clean however too much of the emulsion washes off.
How much time should I add?
Am I coating it thick enough? I think I did a 1/1.
Re: Different exposure times for higher mesh counts.
Hi,
I general, with higher mesh counts you use slightly less exposure time. For me, I use about the same time for 110 and 156. 1&1 is good for 156.
Good luck...Nick
Re: Different exposure times for higher mesh counts.
Hi Bill,
Your time looks like it is the ball park for that emulsion. There are a lot of variables that go into exposure times, included distance, mesh, how old the light is, and a lot of other things, so there is no one time that will work for everyone. The good part is that once you figure out the time for the mesh and emulsion you will be good until the bulbs start to wear out. Search "exposure calculator" here and you'll find some good explanations on test to run to figure out the time.
Sometimes its the opposite of what you think. If you photo-positive is not opaque enough, some light will get through it and partially develop the emulsion. It will then take a lot more water/pressure to to wash out your image. Too much water will eventually wash out the parts you do not want to wash out. This can make you think you didn't develop it long enough when it is actually the opposite. If this is the problem, double up the positives, and try again.
Re: Different exposure times for higher mesh counts.
Actually the text is washing out fine and is the best part of the screen. It is the body of the emulsion that is to thin and washes away too much. Maybe I will try 2/2. I remember the first screen I coated, it was funny it took me like 6 times to cover the screen. But the coat was good. Maybe I will have to go back to thicker coats.
Re: Different exposure times for higher mesh counts.
I use the same time for all my mesh from 86-305 using Prochem DXP. I've never had any issues. If you do have issues, you just have to trial and error. Everyone's setup is different, and it is almost impossible to be specific on what would work for you.
Different exposure times for higher mesh counts. 
