We've got a few issues with screen-printing t-shirts.
- We use water-based inks from a company called Zydex based here in India (can post link to their website if that'd be helpful/allowed)
- We use a conveyor curer at 175 degrees celsius - so at about 350 F for ~1.5 minutes
- We fuse at 160 C/320F for 6 + 3 seconds. The compressor runs at 6-8 bar if that's relevant (not sure how that translates to pressure on the T-shirt itself).
The fuser and curer are new machines, so we're still figuring out how best to use them - any suggestions are welcome.
1. When printing designs with vertical or horizontal lines, we've found these have tended to curve. In the past this has been minor, to the point where I don't think it would be noticeable on the body, but a design we're printing at the moment with 2 long vertical lines has been skewing to quite a noticeable extent.
We've checked and the lines are dead straight on the platen, so my guess is either:
A) stretching of the fabric when put on/taken off the table (we gum the shirts to the table as we print 2-3 layers of ink)
B) ink contracting as it dries (the design has a solid block and then some dots, so we wondered if the solid block could be contracting and pulling the fabric in with it - maybe?). Perhaps connected with new machinery? Can post a picture of the design if this would help.
My gut feeling is that it's A, in which case I'm really not sure how it could be solved. Has anyone come across this before?
2. When fusing we've been noticing small 'craters' appear in the solid block of the design. However, no ink is coming off onto the fusing paper. This hasn't been that big a problem, as we've found with a second/third fuse the craters generally disappear, but if anyone has suggestions as to why it might be happening, we'd still love to know.
3. We've had a few issues with wash-out, particularly with thin lines. We'd hoped the new machines would solve this (previously we fused with irons). I did some wash tests with our new work flow and there was an improvement, but we still got a lot of cracking, even on the first wash/dry (this was a hot wash/machine dry whereas we've only been doing cold wash/air dry - how much difference would this make?). Some designs were fine, others were really quite bad, which suggests to me it's probably either a printing or ink issue, rather than curing. Any thoughts?