I am struggling with getting a 110 mesh screen to wash out without washing out the image and or bubbling of the emulsion around the image. I am using a Black Max printer with spot color text only so there isn't a lot of detail. I am printing white ink on a dark color so I have one layer of emulsion on the front of the screen and three on the back. I have tried with only two on the back as well but am not getting different results. I am using a 20x 24 light unit to burn the image with good pressure/weight on the screen. I have increased my exposure time ranging from 4 to 10 minutes but it still appears that the emulsion isn't exposing enough because the emulsion still feels slimy on the front. I am having to use quite a bit of water to wash out the image which I assume is causing the bubbling. All my equipment is fairly new and the emulsion is a brand new gallon that I ordered about two weeks ago. I have doubled up the image to ensure that they image is opaque enough. Could it be that I need to expose the screen longer than 10 minutes? Could it be that the emulsion isn't dry enough before exposure (I let it dry overnight with fan and a dehumidifier running)? Any other suggestions? I haven't had any issues on getting a screen to wash out prior to now so I am at a complete loss!
Make sure that you empty the dehumidifier otherwise it is recirculating wet air. Bubbling is usually an indication that the humidity is too high in the drying area.
With three coats of emulsion you definitely need to increase your exposure time. If after exposure it is difficult to washout you are over exposed and need to reduce the time not increase it. There is a balance to find when you have multiple layers of emulsion on the screen. Especially if humidity is a factor then you are trapping moisture in the layers below.
Try doing a step wedge test to determine the exact time needed for your coating method and emulsion.