screen printing > Waterbase and Discharge

Discharge buildup on underside of screens

(1/5) > >>

cclaud3:
I have read the other TSB threads regarding this but don't see a definite answer. Assorted responses include:
off contact too high. we are using minimal OC
use higher mesh. tried up to 280
don't flash. doesn't work at least at the temps we have tried below.
underexposed screen. maybe this. using saati single point led but looking to go back to metal halide.

Matsui brite discharge base
Quick additive in our mixes
Mesh count ranges of 150 S, 225 S, 280 T and still buildup.
Squeegee hardness ranges of regular 80, triple 70/90/70, 60/90/60. Happens with all hardnesses
Double stroking. Single stroke won't work on 225 & up mesh. Single stroke doesn't provide a solid print.

Colors that are flashed do not buildup. But I understand the residual flash heat in the platens could be causing the problem.
Have tried both of our ROQ flashes at 60-90 Celsius.

Wiping screens every 30 shirts. Pre-wiping with water (suggested in another thread) doesn't effect it positively.

If I could flash between every color we would be good to go.

Thoughts?

brandon:
The colors / pantone's that have white in the mix put later in the print order. What are your problem colors? I know it's not all of them

cclaud3:
Thanks, nearly all of them have some white base. The clear-only colors aren't as much of an issue.
What do you do when you have 5 or 6 ink colors with 2 flashes?

The very last one was black (225 mesh), 4675C khaki (150s mesh), flash, cool gray 5C (225 mesh), Super 75 white (150s mesh), flash, 185C red (150s mesh). 150 shirts

Job before that was 1625 (225s mesh), 431C (150s mesh), flash, 7499 (225), 7506 (150s mesh), flash, 7485 (225), white (155). 600 shirts

We are running 2-4 of these type of 4+ color count jobs everyday.
Caking up on every 2nd screen after the flash. Everything flashed is fine.

Frog:
Plastisol inks have always had this problem as well, though with the development of wet on wet print friendly inks, it got more manageable. At any rate, the band aid we used was spraying the subsequent screens with silicone spray (or even Pam)

cclaud3:
I agree they both have their intricacies. After printing plastisol for 12 years we moved to 100% wb at the beginning of the year. .

We just never had the caking up that results in distressing the print. Just takes 2 dozen or so prints to start.
You can pick the rubberized pieces off of the print and backs of the screens.

I know I'm not the only one. There are numerous threads on here and other forum sites discussing this same issue. No confirmed solution. Only mentions of possibly underexposed screens, too much off contact, mesh count, flashing vs no flashing. We are getting good exposures with great durability. Post exposure on every screen the day before printing.

I can try the silicone spray.

Navigation

[0] Message Index

[#] Next page