Poly White Flaking

[mpot]

I printed some Badger 100% poly shooter shirts today for a local youth basketball team. The design was white, orange and red. So I printed the white, flashed, printed another coat of white, flashed, then printed the orange and red on top of the white. While it was on the machine it looked really nice. The white was really opaque. The colors popped of the shirt. Then I pulled the shirt off the platen and it flaked and popped off like it was dust? Never had this happen before. Anyone else have anything like this happen? What did I do wrong? White was WM Plastics Ultra Poly HOLB white.
Thanks,
Matt

[Colin]

Is the material stretchy at all?

Do you have a ton of tack down?

[Printficient]

Were you curing the print with your flash?

[mraph]

did all of the ink flake off or just a layer ? that quick it may be inter-coat adhesion (over flashing).

[mpot]

Colin - yes the material has some stretch to it. yes more tack than normal.
Printficient - I was not curing with the flash, or not trying to. It was set for 4 seconds, machine was cold, after 4 seconds it wasn't dry so i went around again.
mraph - not all flaked off, nothing consistent about the failure.

[GaryG]

did all of the ink flake off or just a layer ? that quick it may be inter-coat adhesion (over flashing).

99% this if "top colors" flaked like dust.
Otherwise a 4 sec flash might of been under cured and separated due to not being gelled properly.

Take a ruined one and test a half of dozen times with different parameters.

[alan802]

Most (not all, haven't tested them all) of the poly whites have low flash times, very low actually.  4 seconds with a quartz flash is too long if it's a good flash that is warmed up properly.  If you have a really hot IR flash it can overflash almost as fast as a decent quartz unit.  Next time you do something like that, I'd run the press around a few minutes and let the flash get up to it's optimum temp, pallets get warm, then cut your flash times down by at least 25%, can probably get away with more if things are warmed up nicely, then start the print run.  We run a ton of poly shirts with poly white inks and flash times are quick and those inks seem to be very picky about conditions at times.  The ink will bubble up in the dryer if your temp and time is too high, giving it a orange peel look so watch out for that as well. 

[ScreenFoo]

My guess is that you're exceeding the elongation of the ink--because it's only flashed.  The ink film is pretty weak when it's only 'gelled'.

Same thing happened to me with that ink on some UA shirts, the only solution I could find was less tack.

[mpot]

Alan802 -  we have an RPM with quartz flash units.

ScreenFoo - I think our tack was excessive, backing it off may help as well.

So from what everyone is telling me I over flashed. I will try some different sample times.
When I ran the press around the first time the ink hadn't gelled to the touch, so I went around again. The second time it had gelled (to the touch) but now I assume too much. Kind of a tricky situation if you are suggesting to cut the time by 25%, so only 3 seconds instead of 4.

Thanks for all the info.

[Colin]

My experience says the flaking/cracking was exacerbated by to much tack.

If the garment had almost no stretch, you would barely see any cracking and have no real issues with the amount of tack you had down.  Back off on your tack, be gentle with your flash times and you should be right on the money.

[Nick Bane]

My guess is that you're exceeding the elongation of the ink--because it's only flashed.  The ink film is pretty weak when it's only 'gelled'.

Same thing happened to me with that ink on some UA shirts, the only solution I could find was less tack.

sounds like ink cracking from being stretched as its pulled off the platten, from too much adhesive.  less tack and be gentle with your pulls should cure that.

[mpot]

I just did a sample test and went to the extreme. I heated the ink to way beyond what it should be the put a second coat on it then heated it again way beyond (the shirt was smoking! ) then pulled it off. no problem with adhesion between coats.
Then i just barley heated it to the point where it was just barley lifting off to the touch. I did a second coat and the same thing no problems.
I tried to do a test just the way we did it yesterday and again no problem.

Although I didn't solve my problem, thanks to all for your help, at lest i'll have somethings to look for when and if it happens again.
Matt

[alan802]

That's weird.  I've never heard of ink coming off like you mentioned but when you said 4 seconds and on the same flash unit we use I know that's twice as long as we flash for with poly whites.  We've also never had any real issues with adhesion between layers of ink so troubleshooting that is new to me.  I've heard that problems arise when overflashing but I've never personally experience them so I think the latitude for flashing is higher than most think cause I know we've flashed the heck out of things in the past with pallets over 180 degrees and didn't have adhesion problems.

We've seen top colors crack when taking shirts off due to excessive pallet tack but never what you described.  Was it really dry and was there lots of static in the air?

[mpot]

Yes it's really dry and a lot of static. The ink jumps to things like its alive!  But that is the same every day. We do run a humidifier this time f year but it doesn't solve the problem.
I do think tack has to do with it especially after the tests today.

WM rep to me to heat it more between coats thought it was under flashed.

I've ordered new shirts so i'll get to do it again anyway.   

[mpot]

Reprinted these yesterday and had no problems. I'm convinced that as some mentioned it was excessive tack and excessive stretching.