"He who marches out of step hears another drum." ~ Ken Kesey
I had this exact same issue last week when running a 2 color print. My print was light pink flash light blue and the tape ended up getting basically damp and not holding all too well.I think the issue was that I was pulling over the registration mark that was taped, a little bit of ink or even outgassed ink vapor made it through the tape and since the tape was kind of damp it left a very faint impression. My solution while printing was to not print over the registration mark and that seemed to work. In the future I'm going to move the registration marks further away or try out a different tape.
we call this screen sweats. This is typically from a screen that's breakdown, where the tape is trapping the pigment, but letting the discharge base seep out. So you'll get lines you'll be chasing non stop.
Quote from: Pangea on November 30, 2018, 10:44:13 AMI had this exact same issue last week when running a 2 color print. My print was light pink flash light blue and the tape ended up getting basically damp and not holding all too well.I think the issue was that I was pulling over the registration mark that was taped, a little bit of ink or even outgassed ink vapor made it through the tape and since the tape was kind of damp it left a very faint impression. My solution while printing was to not print over the registration mark and that seemed to work. In the future I'm going to move the registration marks further away or try out a different tape.I had that same issue. I thought it was the registration marks too. So on the next job I didn't even use registration marks. I taped them off on the inside of the screen with clear tape, put the screen on press, laid out the film on the pallet, and registered the screens to the film rather than printing my key screen and registering all the other colors to it. The issue still happened. I thought maybe it was too much squeegee pressure, so I backed it off A LOT and it still didn't solve the issue. I think Eric is spot on about what's happening. The way he describes the tape trapping the pigments, but allowing the discharge through sounds right to me. This was happening on a longer run than what I normally do, so this was new territory for me. I was in the middle of a 240 piece order when the line started showing up. Maybe my screen wasn't post hardened enough.
I use the LXP emulsion from CCI, which is supposed to be good for discharge. I also post expose it to try and prevent breakdown. Is there anything else I should try to harden the screen more without sacrificing the ability to reclaim it? I know you print a ton of discharge, so is there a certain tape that you've found that doesn't allow the discharge base to seep out?