This again.

[Screen Dan]

Back in my printing days whenever this would happen there were some pretty consistent parameters that seemed to lead to it...and to be clear, this is markedly different from fibrilation from crappy garments or too much pressure/bad tension/poor squeege choice/etc.  First parameter being a solid base with a heavy lay-down.  The second being a solid over print...heavy lay-down or not didn't matter.  Double stroking the over-print helped very little and always lead to pickup if there were any screens after the trouble-color. 

My theory was always that the flashing was happening too rapidly and creating microscopic bubbles in the underbase.  Whether this was from moisture in the garment causing microscopic steam bubbles or just the ink I never really figured out...Getting the base plate on a higher mesh usually helped and/or setting the dwell timer so that it spent more time under the flash with the table lowered than raised with plenty of flashing.  This is all assuming you are using minimal pressure, which it seems like you've covered.

But, that feels like eons ago.  This was with Pop White going through a 160 with thick threads and all the phthalate you could ever ask for.

Definitely report back, I'm always curious about how others approach common problems.

[jonbravado]

Screen printing can be so aggravating.

I've heard mostly great things about quick white - I need to try it again.  Our go-to lowbleed white is 711 white by I.C.  It lays down super smooth and is very opaque.  Not as cheap as the quick, but seriously good ink.  It floods well, prints well, and blocks dye migration better than anything (without puff additive, anyway) that we've tried.

Someone needs to invent a heat-press we can put in head two to flatten that base down to perfection.  That'd be sweet.

I don't think there is a silver bullet for this problem though.  Garments are so inconsistent (not enough heat used to lock in dye anymore) - each batch has it's own pitfalls to avoid.  They don't make stuff like they used to.

Good luck, and know you're not the only frustrated, pulling their hair out, screen printer today 

J

[jvanick]

Someone needs to invent a heat-press we can put in head two to flatten that base down to perfection.  That'd be sweet.

M&R has it already

it's called the I-Kiss

http://www.mrprint.com/en/Textile%20Screen%20Printing%20Equipment/On-Press/Textile%20Accessories/i-KISS%20Automatic%20Heat-Assisted%20Substrate%20Press

[jonbravado]

Sweet.  Any idea on MSRP? 

[GaryG]

My theory was always that the flashing was happening too rapidly and creating microscopic bubbles in the underbase...

Or -any- flashing of the Quick, just the blowing agent (slight puff) making rought surface and too thin of top coat skimming over craters and not allowing to fill in.
Love quick for many things, but Wilflex Sprint has been a great underbase on many shirts here lately.

[jvanick]

Sweet.  Any idea on MSRP? 

I believe around 3k.

[ZooCity]

ScreenDan and Evo, that's the conclusion I came to- combination of the flash heat and ink causing the bubbles/craters.  There's little more that could be done with the print parameters at this point, the UB is totally deluxe aside from the issue at hand.   I had a hunch based of the conversation with bimridder that the quartz heat maybe is not ideal on this base when it's a solid fill area like this.  If time allows I'd like to swap the IR and quartz flashes but honestly, if Quick can't hang printing a solid spot color base and being quartz flashed, it's time to replace it.  We're not zapping the base by any stretch, flash is around 6 seconds I believe.  Unless Wilflex has a more premium white I don't know about, IC phthalate-free Legacy White is next up to contend for the throne of our plasti white- there can be only one. 

In the end we resolved this with a much slower UB stroke, extreme dialing in of the first color to get a safe 1x stroke since it's printing wow, and then double stroking the second which gets a flash after printing.  Lost some opacity by adjusting the UB stroke to accommodate the issue v. setting it for the best ink lay down but a small tweak on the highlight white solved it. 

I don't think a unit like the i-kiss would have necessarily helped here unless it actually re-melted the base into a solid film.  The smoothing screen right after the flash is doing a similar job. 

It's true, there really is no "fix" for this one.  Funny that it's so common.

[ebscreen]

Can't recall if you have intensity control on your quartz flashes? That's what I'm going to try next time I see this.
Longer time, less hot.

[ZooCity]

Can't recall if you have intensity control on your quartz flashes? That's what I'm going to try next time I see this.
Longer time, less hot.

We do.  I wonder if the intensity controls actually exacerbated the problem as my understanding is it basically pulses the bulbs rapidly v. just turning down the juice, that has to create a different kind of wavelength I imagine.   I put the flash back on 100 to eliminate that variable.

[ScreenPrinter123]

We're not zapping the base by any stretch, flash is around 6 seconds I believe.

How many bulbs, what wattage and is all 6 seconds in the table up position?  6 seconds would cause some serious problems during a job for us.  Since you know far more than me it must be a difference in the flashes so I was curious as to what it is.  We start out a job (after preheating pallets) with the flash at 2.5 seconds and if running two flashes on our 12 color are usually at .8-1 second on flash one and .6 on flash two once we are into the job and running steady.  Our flash is run at 80% power while flashing and 20% during standby (while tabled down and indexing).

[ZooCity]

First off, if printing has taught me anything it's that I don't know chit mang.  Second, it's a great point about the flash times. 

Ours is a Red Chili 2024, not the D, but one with intensity control.  3ph, on a 40a circuit.  The unit has always seemed a little underpowered or something so I upped the circuit to 40a when we moved, but no noticeable difference.  I don't know the exact wattage, probably around 7k or so.

≈3-3.5" off the platen in table up position.   We run all zones on, all the time.  Zoning leads to super long flash times and inconsistent flashing typically.

The softstyle Ts were flashed at 7s, 100 intensity.   I fiddled with the flash a lot, thinking over flash was happening but even at 90-95, the ink did not flash.   

Hoodies on the press now are at 8.5s, 75 intensity. 

It's always seemed like our times/intensity were super high but any lower and the ink isn't flashed. 

[ebscreen]

20% during standby (while tabled down and indexing).

This is likely the major difference between your flash times. Wattage as well, but having the bulbs pre-heated
make a big difference. We run no standby, as once the pallets are warm flashing takes less time than printing.
Saves energy in my mind, but I could be wrong due to the increased power required to heat a bulb from zero.

[patfinn]

Chris,

Red Chili manual says 2.25" off the pallet in up position. I am usually anywhere between 2.25 and 2.5" off pallet in the up position.  I am measuring from the bulbs to the pallet. The only time that I would adjust height is for sensitive fabrics, but you can achieve the same by dialing down the power.
Call me if you have any more questions.

Patrick Lashbrook
The M&R Companies
Office : 1 630 446 7176
patrick.lashbrook@mrprint.com

[ScreenFoo]

In the spirit of the 'advice' thread, I'd suggest something, but it would be 'wrong'. 
(Pierre got real close, but I don't know that anyone got it:) )

[ScreenPrinter123]

I know the standby time helps and is what was suggest to us my Mariusz.  I don't remember exactly why but if my memory serves me well I believe he mentioned it being more efficient because going from 0-80 was much harder than going from 20-80, I also think it helps with bulb life but I could be pulling this all out of you know where without realizing it!

We also have 12 1600 watt medium wave bulbs and they are roughly 1.75" away during table up so that will also account for some difference.