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screen printing => General Screen Printing => Topic started by: Gilligan on December 03, 2014, 04:32:14 PM
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Ok.. so I've been trying to wrangle proper belt speed and such and we are struggling.
Donut probe isn't consistent and I want to trust it but sadly I've heard it's not good for infra red.
So we have been stretching and using non contact gun. Results stretch fine gun shows 430... we've sped up the belt for poly's. We've had bleed issues when running non poly inks on poly.
So I said f it I want this right and ordered a pile of thermal strips. 5 step and 8 step (8 goes to 390).
Threw a red cotton shirt on the belt and an 8 step, because I knew we were cooking them too hot.
Comes out the dryer untouched... 290 didn't register... had to run it through three times to get 330 to be black.
Pulled out a 5 step strip, thinking maybe these aren't good for this, same thing... photo to follow.
Ran it through the second time and got a few to go black. Pic following.
We've printed shirts for my wife's company and the girls wear them daily. Washed at least 4 times probably twice that. No signs of problems and not a single call.
Dryer is running at 1050, belt at 13 which equates to 30 seconds in the tunnel and panel height is 6". 3 panel 6' tunnel on the 2009 Radicure.
Shirts are streaming coming out the tunnel and even the cotton shirts are hard to handle. I bought gloves to handle the 50/50's and poly shirts as they are impossible to handle off the belt. Never had shirts that hot coming off the Chaparral and we never had under cure issues EVER.
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Pictures as promised.
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2nd time proof.
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*crickets*
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slow down the dryer! Use the temp gun as it should be pretty close. try not to go over 350!
pierre
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Yes temp gun at consistent height and angle. Wash test, of course you know these.
*crickets*
These fry nicely well below 350. :)
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Maybe the labels are beyond their expiration date, I think 2 years is the max. Also the are to be stored in a cool dry place, preferably refrigerated.
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I'm also using an infrared dryer. My shirts dwell for just over a minute in my tunnel, and I have the baffles pretty low. I get my temp gun right up to the exit baffle and test about 8 inches from the baffle, on both sides and in the center of the belt. Sides are always hotter by about 10 degrees in my dryer for whatever reason. My exit temp is 330-335 on the shirt in the center. Never had any curing issues and I only adjust on problem colors and low/no cotton stuff. Discharge is a different story and I have forced air etc.
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slow down the dryer! Use the temp gun as it should be pretty close. try not to go over 350!
pierre
P, we are temp gunning them at 430 now! So slowing the belt down doesn't make sense if I'm trying to not go over 350. :/
Maybe the labels are beyond their expiration date, I think 2 years is the max. Also the are to be stored in a cool dry place, preferably refrigerated.
These were JUST purchased straight from the manufacture, not a supplier.
*crickets*
These fry nicely well below 350. :)
LOL
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A couple of things, though neither solves your problem:
1.Back when I cured with a four foot Scamp, I used these strips, except that I used them on the inside, to really assure me that the bottom of the ink layer was cured.
2. With you being a tightwad (like me lol!) I can't believe that you are using those things full width! I always cut them down the middle to double my stash.
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I paid only $10 bucks a pack (16 to a pack)... I'll probably cut them later, thanks for the tip! I just didn't want to introduce variables.
On Pierre's suggestion I fired up the heat press to test these strips.
So... didn't REALLY solve anything, just added more questions.
RESULTS: At 320 on the press for 30 seconds the strip was showing a partial 320 (50% blackened) the digital read out had dropped to 316 as the platten/shirt was sucking the heat away from the platten in that 30 seconds.
ALSO: I ran two temp guns at the press the whole time it was heating up. Showing fairly accurate temps (given the reflective nature of the element). I would press it down for 30 seconds and shoot the platten as soon as the element would lift and it was almost on the nose temp wise there. So I was pretty confident.
THEN: put a shirt on and did the same as above and it showed WAY lower (270)... but the strip still showed 320 underneath a teflon sheet with 30 seconds pressing.
SO: as I said, no real answers just more questions. Yes the strips are activating at the right temp and yes my heat press is still rocking and rolling... furthermore yes my temp guns are both working (withing about 15 degrees of each other at the 300 mark)... BUT the questions are still, since EVERYTHING is still technically working why does my temp gun show 430 while the strips aren't being even lit up at 290.
*sigh*...I guess I will call the company tomorrow to see what they say about those strips. They are meant for screen printing according to their site.
Pierre is thinking that with the amount of air flow the Radicure moves that maybe the air in the chamber is getting up to temp as well. I'm thinking about dropping in a oven thermometer that I have laying around if I can find a place to put it (I just figured out how I'm gonna do that!)... I'll also attache a temp strip to it as well. This will be hanging down in the empty panel spot so it won't have any direct IR. I don't expect this to hit actual temp that the garment will see... but I'm curious as to what it will see.
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The temp strips have more thermal mass than your t shirt material. They heat up at a different rate. The infrared temp gun also measures over a small area rather than just under that laser dot. So, unless you are aiming at a larger printed area with a relatively thick ink deposit the temp strip nor the infrared gun are a true indicator of ink layer temp and the test strip is definitely not going to indicate the shirt material temp (which will be higher than the test strip).
I'm generally printing thin layers of ink and a lot of the designs don't have large printed areas to shoot at, so I'm essentially monitoring the shirt material temp and inferring what the ink layer temp is. Printing poly sucks when you have to go as low in temp as you can. Slowing down your dryer and lowering the panel temp helps because the rate of change is slower and it gives you more latitude. It's easier to hit a sweet spot in temp and time but at a production cost. I personally don't know how to set my dryer at it's lowest cure temp without wash testing.
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The temp strips have more thermal mass than your t shirt material. They heat up at a different rate. The infrared temp gun also measures over a small area rather than just under that laser dot. So, unless you are aiming at a larger printed area with a relatively thick ink deposit the temp strip nor the infrared gun are a true indicator of ink layer temp and the test strip is definitely not going to indicate the shirt material temp (which will be higher than the test strip).
I'm generally printing thin layers of ink and a lot of the designs don't have large printed areas to shoot at, so I'm essentially monitoring the shirt material temp and inferring what the ink layer temp is. Printing poly sucks when you have to go as low in temp as you can. Slowing down your dryer and lowering the panel temp helps because the rate of change is slower and it gives you more latitude. It's easier to hit a sweet spot in temp and time but at a production cost. I personally don't know how to set my dryer at it's lowest cure temp without wash testing.
this! That is the reason I said to slow the dryer down. Try going back to 10" of height and longer dwell times. . .
pierre
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I think it maxes out at 7.x" of height... I know it doesn't go much higher... maybe 8.x".
I can turn down the temps for sure, will probably save me some money.
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I think it maxes out at 7.x" of height... I know it doesn't go much higher... maybe 8.x".
I can turn down the temps for sure, will probably save me some money.
set your panel height to 4" and adjust your temp to 950 with a 30 second retention time. That is a good starting point.
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Will do Rich, thanks!
FYI, we ran some transfers just now. Cranked it up to 43'/min (left it at 1050 and 6") and they were coming OUT of the dryer at 270! Dry to the touch and pressed perfectly.
I ran a sheet of embroidery backing as a test and was getting 430 under the last panel even at 26'/min.
Still don't really know the proper way to test what temps we are actually seeing. :(
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I think it maxes out at 7.x" of height... I know it doesn't go much higher... maybe 8.x".
I can turn down the temps for sure, will probably save me some money.
set your panel height to 4" and adjust your temp to 950 with a 30 second retention time. That is a good starting point.
Just tried a version of this.
Dropped temps, dropped panels, but left the belt speed up (19) and shirt hit 430 on the infrared as it was about to exit the dryer.
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I think it maxes out at 7.x" of height... I know it doesn't go much higher... maybe 8.x".
I can turn down the temps for sure, will probably save me some money.
set your panel height to 4" and adjust your temp to 950 with a 30 second retention time. That is a good starting point.
Just tried a version of this.
Dropped temps, dropped panels, but left the belt speed up (19) and shirt hit 430 on the infrared as it was about to exit the dryer.
speed up the belt and should be there
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Also the Thermal Strip doesn't register anything.
I'm still just as baffled here.
Just ran a shirt through at 24 and stretched ok but doing a rub/scratch test the ink is coming off on the shirt. One gun was saying 330 one was saying 430 but I didn't reach in as far with the 330 one.
Seems like there would be a definitive way to make sure your dryer is getting to X degrees on the garment/belt.
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Seems like there would be a definitive way to make sure your dryer is getting to X degrees on the garment/belt.
I know that you didn't think much of it, but some folks consider the Atkins Donut probe, with its wires buried in the ink layer just that.
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I have one and I've done that. Shirt comes out almost too hot to handle... yet probe was showing well under 300. :(
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I'm still hanging out at the shop, catching up on some PC work, so I fired up the dryer and printed off me a shirt. Double stroked some Royal Blue, flashed it, double stroked it again! (single would have been fine for any job... but I wanted to lay some ink down).
Slowed the dryer down to 30 seconds in the tunnel at 950 and 4" panel height. I pulled out the donut probe buried it in some ink, placed a thermal strip on TOP of the ink. Ran it through.
Donut probe never hit 250, thermal strip didn't light up one thing (lowest is 290).
YET, ink seems pretty darn cured, flaked off of the donut probe's wires. Pulled the thermostrip off and the ink even seemed cured underneath it. Stretch test look good, scratch test looks good.
FYI, it's not a bullet proof deposit, just thicker than it needed to be for the light garment (baby blue). It's Union Ultra soft series royal.
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We had our first call about a shirt that the print was coming off on.
Was part of a 900 pcs job... REALLY hope it's a fluke. We know it was fleece and we know we had some print issues on the fleece and hit a couple of them a few times to get it right. So we are HOPING it was just a really thick print on that particular shirt. Possible fleece isn't getting washed as much the regular t-shirts so no one is really discovering problems? Not sure, we are obviously replacing this one, luckily we are doing a repeat of the order as it's a 5 color job. Fleece was 182 out of the 900 pcs, so that might be the common denominator.
Just sucks... crazy thing is we never had a single garment come back or call when we were running our little Chaparral for all those years. Now we get this big bad Radicure and we can't seem to get it right. :(
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We had our first call about a shirt that the print was coming off on.
Was part of a 900 pcs job... REALLY hope it's a fluke. We know it was fleece and we know we had some print issues on the fleece and hit a couple of them a few times to get it right. So we are HOPING it was just a really thick print on that particular shirt. Possible fleece isn't getting washed as much the regular t-shirts so no one is really discovering problems? Not sure, we are obviously replacing this one, luckily we are doing a repeat of the order as it's a 5 color job. Fleece was 182 out of the 900 pcs, so that might be the common denominator.
Just sucks... crazy thing is we never had a single garment come back or call when we were running our little Chaparral for all those years. Now we get this big bad Radicure and we can't seem to get it right. :(
did you do the wash testing? if it passes there, that's another clue . . .
pierre
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also, dial in the temp, speed and height so you have 60 sec reten time and see what comes up on the probe, gun and strips.
had to run it through three times to get 330 to be black.
this tells me that you need to build up heat in the strip and that you don't have long enough dwell time, but it's as good a guess as any. . .
pierre
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Didn't have time to read all this so it may have been said, forgive me if so. You are introducing more than just a new dryer to your situation, you could be over/under flashing your base as well that could be part of your issue if you have some washing off. Just food for thought.
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Underflashing would be obvious on press and wouldn't have anything to do with washout issues.
And in ten years I've yet to see an overflashed base with intercoat adhesion issues, and we've certainly cooked
some bases. Concept is sound but given correct temps in the dryer it should all melt together.
I'd chalk it up to a new dryer. It's always a head scratcher finding your settings when you were used
to something else. Wait till you go from electric to gas...
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We run Radicure dryers, 10ft. chambers, elements set at 5". Plastisol- 830f belt speed 13. Discharge/WB- 700f belt speed 4. Readings from the temp gun range from 350-370.
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Didn't have time to read all this so it may have been said, forgive me if so. You are introducing more than just a new dryer to your situation, you could be over/under flashing your base as well that could be part of your issue if you have some washing off. Just food for thought.
That's a good point, but we try to get just past dry and if still tacky just past that. At the end of a run we might have the plattens warmed up but usually they aren't unless we are really moving. This was also coming back from printing the tees... so we didn't really have any change to warm them up (we don't warm up plattens with the flashback). So it SHOULDN'T be that.
Underflashing would be obvious on press and wouldn't have anything to do with washout issues.
And in ten years I've yet to see an overflashed base with intercoat adhesion issues, and we've certainly cooked
some bases. Concept is sound but given correct temps in the dryer it should all melt together.
I'd chalk it up to a new dryer. It's always a head scratcher finding your settings when you were used
to something else. Wait till you go from electric to gas...
In Brandt's defense (did I just say that?! ;) )... we did just also get a new press and flash. But as I said above, I don't think that was the issue.