Printing issue

[TL]

Anyone run into this problem like in the attached picture?  Print is: White base - flash - white base - flash - pink  done on an automatic, plastisol ink.   There are faint diagonal lines running through the pink.   We tried just one base underneath and it wasn't any better.  We re-exposed that piece of film on a new screen, didn't help.  I have never seen this before.  Any help/suggestions are appreciated.  Thanks

[blue moon]

that might have something to do with off contact. Make sure your screen is pulling out of the ink while printing.

pierre

[Frog]

Are the irregularities consistently located? Probably not exactly.
Pierre's suggestion of off-contact being involved makes me also wonder about the temp and tackiness of the underbase.

[Sbrem]

I'm thinking your plate is not perfectly flat perhaps? Or, the flash is missing a spot, broken bulb maybe?

Steve

[screenxpress]

It looks like the same faint parallel white lines are visible in the "R" above the Pink image. 

If that's right, then the Pink screen may not be putting down enough ink (or is a coarse halftone) and is allowing the the faint white lines to show through the Pink.

Is the white (after flash) still sticky causing the screen to snap back and pulling up some Pink leaving some of the white underbase exposed?

The white underbase almost looks like a mosaic texture print in itself. 

Just my thoughts

[Colin]

Can you tell me the mesh counts involved?

It looks like a possible pattern interference from your mesh...

[Squeegie]

My vote would be that it is in the base print.  Possibly too low of a mesh on the base and too high on the pink, so it doesn't fill the pattern.

For a print flash print, it does not appear that smooth.  Lots of fibers still poking out as well.

[TL]

My initial thought was that the underbase was too hot when the pink was printed but we did a test of letting the underbase sit and cool for approx a minute and got the same result. 
All 3 screens are 123 standard mesh.  Never had this problem before, although we usually don't do 2 whites as an underbase. 

[cclaud3]

The only time we've seen this is when the same mesh count is used for the underbase & top color (by accident).

[tonypep]

Pinks/Magentas/reds are the most fugitive colors and subject to many variables. Mainly heat. Hard to diagnose without boots on the ground however.....make sure that UB is perfectly flat as mentioned. Iron or roller screens will help with this. These inks can also be semi-transparent. I would advise to check with the ink mfg as to formula or switching products. The list goes on

[ericheartsu]

that might have something to do with off contact. Make sure your screen is pulling out of the ink while printing.

pierre

this was my thought, or the screen tension was to low, and it was sticking in weird spots.

[ABuffington]

Base Mesh + Overprint mesh interference.  Try switching to a higher mesh count than the base.  Sometimes you may need 2 color overprints with a finer mesh to get color and eliminate the mesh interference.  The shirt fabric can also contribute to this.  Running a bias stretched base can eliminate the pattern in the base that may be causing this interference.  Like Tony mentioned, use a flattener screen on the print or iron on the shirt to minimize shirt fabric pattern. 

[screenxpress]

I didn't read anyone else mentioning this, but my underbases under colors are always halftones in themselves about 60% dots.  This almost looked like a solid underbase. 

My underbase would be a 168 mesh, solid image for the white, halftone for the pink and P/F/P/F/Pink

I'm probably over my head on this but it usually works for me, lol.

[alan802]

I think the other Alan got it 100% right.  We see this a few times per year and we always fix it by changing the base mesh count and/or the top colors mesh count.  Like A said, shirt fabric is the final piece of the puzzle.  We do most of our test prints on cotton and will have no issues but then if we throw a shirt on the pallet that has a high density weave the mesh interference will show itself.  It's usually not that noticeable on a plain jane cotton T.  We rarely print two layers of underbase before the top colors but if we do on a 100% poly/performance material this will sometimes show up.  But it's rare because if we get this far down the road that means I didn't use the right mesh counts.  When we print on dense fabrics we bump our mesh counts up 1-2 levels.

[TL]

Thanks everyone for the input.  It was mostly mesh interference between the 2 white screens but I think it was magnified by the pink being not very opaque.   Out of curiosity, I tested it with a thicker more opaque colour(kelly green) and it didn't show up at all, but I realize that there was still a problem at the fundemental level.