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screen printing => General Screen Printing => Topic started by: ZooCity on April 01, 2015, 03:10:48 PM
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I had to reset a job for my crew that they just couldn't get going. It's very basic, solid fill, plastisol spot color, about as athletic look as our printing ever gets, literally a shield going on a variety of garments. All Wilflex, all IMS mixed:
150/48 Underbase Quick White
Flash (quartz)
Cool/smooth
225/40 Performance blue pms mix *The perf blue covered better. Not uncommon that blues with more body to the ink will cover best.
180/48 Amazing base mixed National Red
Flash (IR)
Cool
150/48 Hilite Quick White
The issue was one that I see from time to time where the top ink colors have little pock marks of missing ink over the base. I attached a pic case anyone isn't familiar but I think most on here have experienced this. Coverage is fine, everything else about the job is great but the pock marks keep popping up intermittently.
I did my usual routine to dial in the job but spent, as all of my crew did before me, what felt like a silly amount of time dialing the top colors in to prevent this issue. I've had it dialed thrice now but it keeps coming up, we can't get it rolling steady for very long.
Experience says this is a temp issue. Too hot/cool on the flash on the UB. But we have messed with the flash temp endlessly and see the pock marks both when over and under flashing and everything in between. My guys preheat and we roll steady once going. It feels like the UB is so finicky that it needs some special magic perfect temp to work.
All this is based off single stroking all, doing it the "right" way. We're running 2x strokes on the colors just to get the job out as it avoids the pock marks.
But what causes this?
I'm starting to think very seriously about finding a new low bleed white that does better as an underbase, I can't help but be suspicious at this point of the ink and I've heard from others that Quick may not be the best for underbasing. We keep having issues with top colors, with wow printing and otherwise that seem really out of place for how well setup everything is. Also, Quick on Quick does not display the issue which seems telling to me but then again, it's white ink on white ink so it may just be hiding the issue better.
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Type of shirt?
How dry/moist is the garment?
Do the pock marks go away if you 2 stroke the white base?
You said you ARE smoothing the base white?
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Gildan 64000 Heather Navy. Also will run 2200 Navy and 18500 Dark Heather after these.
Yes, smoothing the 1x stroked base at 40-50psi with a roller squeegee and teflon. Base is printed with 55/90/55 at lighter pressure ≈30psi. It's strong and with singles all around, 70/90/70 for all others, it's plenty of ink.
I'd say the garments are fairly dry, it's always pretty dry here but in constant flux as we get bouts of precip most days in the Spring. About 15-20% humidity in the shop on the hygrometers right now.
I'll try the 2x base but I know the guys have probably already been there and it will be too much ink I fear.
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Only time I have ever seen this, it was the underbase was not flashed long enough on the first few prints. Clean your blue screen and your roller. Then start again with hot pallets and flash longer on your first 12 shirts.
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we've had this happen a ton too. always had to clear out with 2x strokes
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Was just battling this on an 8 color print, 2 of the colors were doing this, changed to 60 duro squeegees on those two and problem solved.
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We've seen it as well, and usually on thinner/transparent pigment type inks.
2x stroking, softer squeegee, whipping ink through the screen etc will fix it, which makes
you think it's an issue with the top color. Thing is in reality it's likely the base, and it's not
one of the usual base suspects, IE fiber matte down. I think you are on the right track with temp.
Also, I don't readily recall seeing it when we were using StreetFighter.
We have a regular repeat job with big swatches of red (think RUNDMC) where we've taken
to dropping both the underbase and red mesh counts, and using a sixty duro on the red (this in part
due to the chatter we get from to solid lines parallel to the squeegee, but that's another post)
to be able to print in one stroke all around. Obnoxious and a bit heavier than I tend to like but it
gets it done without all the fiddling.
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Yep, done all that. None of it solves the issue. 2x stroke on top colors barely gets rid of the pocking, still seeing it. And now it's introducing a pickup issue printing blue to red wow.
It doesn't need more ink, it doesn't have an issue clearing, the top inks just won't consistently cover the base in those little pock areas.
Also, seeing this on a wide variety of testers (damn near running through our supply on this one) so I'm ruling the garment out more/less.
The ultra high print speed helps on the red, been running that one fast from the get-go. The blue can't hang with the fast stroke though. Both the top colors need a lot of pressure as well.
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You know you maybe right no it only being a Quick white issue. I think I was using quick when was having that issure with a top maroon print. Most of the time when issues like this come up we fix them with changing print speed and pressure.
I just got in a 5 of quick. I haven't used quick all winter. I used extream white and SF for a while. I will have to see if this comes up again.
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We used to have the issue every once in a while.... Several months back we switched away from quick white and I have not seen the issue since. Maybe it was the quick white maybe it wasn't but I've always thought hmmmm to myself that we have not had the issue since. It was always with blue or purple top colors from what I recall. PM me if you want to know what white we are using
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Not to take away from this post but has anyone ever had a problem that flashing less solved the issue. I know over flashing can blister the ink or burn the shirt. Is there ever a time that an ink is too flashed...
I have not seen it. I know some say that if you over flash a underbase the top color will not stick. I have never seen that.
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I can't help but lean toward the Quick. It's suspect that quick white on quick white or any top color ink that we mixed with quick white in it doesn't do this.
Then again, why is this intermittent?
Dave pm'd me and got me louping the base. It has little bitty craters in it. Some of which appear ink coating inside the crater, like a reverse bubble, some of which don't. I'm slowing down the stroke on the base to see if it resolves. If this crater theory holds any water my next test may be trying the IR flash on the base v. the quartz. I'm thinking the ink could be responding weird (by whatever combination of physical laws) to the quartz wavelengths when using the intensity control and causing the craters.
What I love about this is how dirt simple the print is. It's always the simple spot color jobs that are somehow the most cryptic.
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I have seen issues with overflashing causing issues. Not inter-coat adhesion, but more of a texture issue, the fibers start
to stand up.
FWIW, streetfighter flashes quicker than quick. If we could just get it to stay flooded.
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I have seen issues with overflashing causing issues. Not inter-coat adhesion, but more of a texture issue, the fibers start
to stand up.
FWIW, streetfighter flashes quicker than quick. If we could just get it to stay flooded.
I liked SF. The only problem for me is it has too much puff in it. I usually don't have a flood problem with it after 15 or so prints. But I also flood fast. I like to use my flood as a way to keep the ink flowing. I also have my flood bar up off the screen. I like a thick soft fast flood.
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Seen this before with Gildans. Maddening, eh? I think it's from the Gildans being not the smoothest knit and the ink not holding an even film on the surface of the fabric and penetrating a bit too much.
The underbase gets cavities in it that the top color can't fill without a ton of pressure or double stroking. Key is to get the smoothest white you can manage. I'd try a slightly sharper angle, slower stroke and as little pressure as possible to clear the screen. Get a nice even ink film. Maybe use less pressure on the roller too.
And maybe grab a better white?
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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.
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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 ;D
J
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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 (http://www.mrprint.com/en/Textile%20Screen%20Printing%20Equipment/On-Press/Textile%20Accessories/i-KISS%20Automatic%20Heat-Assisted%20Substrate%20Press)
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Sweet. Any idea on MSRP?
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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.
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Sweet. Any idea on MSRP?
I believe around 3k.
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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.
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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.
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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.
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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).
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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.
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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.
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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
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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:) )
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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.
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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.
Maybe you could lower the power during actual flash and run a standby and let us know the difference with an amp meter and some simple calculations...yes I just volunteered you. :o
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We have a Red Chili D 2024 on our sportsman, and after the first shirts start going under the flash, for a typical Gildan Ultra shirt, the flash time ends up around 4-4.5 seconds (with the temperature sensor set at 200 degrees F) the bulbs are 2.25" above the platen when the table is up.
Ink is quick white, non modified... platens cold. once the platens warm up, the flash time gets even lower...
-- this is one reason I really like the 'D' model of this flash, you can watch the bulbs and decrease the flash time on the press's control panel as you go to index even faster.
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I think this was mentioned already, I lose track as I get older . . . Anytime I had this problem (few years back when I was still printing), it was too much heat. drop your flash times, make sure the ink cools down before printing on it. Slow your flood to a crawl and put a fan on the platen so it blows on it between the shirt and the screen during the flood. Measure your deposit temperature and see what's going on. You also mentioned flashing again, so it all points towards too much heat and cooking the ink in the screens.
pierre
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We're actually at ≈2.5-2.75" from the bulb to platen when tabled up, sorry I had that wrong.
Flash times or intensity drop after the run gets going, seems to still be something needed despite preheating.
Nearly everything we print requires a more gentle flash. We do run some regular, c.o.e. cotton Ts like G2000s and the like but it's ringspun all day most days with lots of blends and also mixed items on runs. We've found that in most cases a longer flash at lower intensity is best. We do have very fast flashes at times but it's the exception v. the norm.
I think slower is better for gelling plastisol. I have the crew flash hotter/faster only if the flash is slowing down the run. I don't have good empirical data to back that up or anything.