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flash unit to cure issues

1376 Views 12 Replies 6 Participants Last post by  nativesonjls
I have worked hard to get the shirts to this stage at a good quality, and everyone on line has been a big part of this, thanks everyone for you advice.
But on the final cure I am having issues.
1) I set the 16x16 flash cure unit at 4 inches above the shirt, largest graphic is 15x15 (the heating elements are similar to a electric oven element)
2) unit is preheated and I can target the surface of the plastisol with the thermometer
3) shirt/plastisol reaches 330 at the outer edges and the center area is around 360+
4) stretch test after the shirt cools seems fine but after a couple of washes the outer letters wash off.
5) I'm afraid to leave the shirt under the flash unit for more than a minute after the plastisol reaches 330 because the center area gets so hot, a few test swatches have scorched.

Can I raise the unit like I do with water based and reduce the chance of scorching or can the shirt stay under longer by rotating the flash unit cooling and flashing again?
I don't want to start selling shirts and start out with shirts that fail, repeat business will be important in making this work.
If I have to I will get a heat press, I was planing on this after a 4 color station but I can rework my priorities if needed.
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It is going to be very difficult to cure a 15x15 design with a 16x16 flash. The problem may be that although the surface of the ink is reaching 330, it may not be curing all the way through. The entire ink layer has to reach curing temp all the way down to the fabric. I am not sure exactly what the scorch temp of a shirt is, but it is well above 400. I would try to get the center of the design to 400 and see what happens.
Cure half the design and then the other.
I will run some test with the swatches both with increased temp a center which will allow the edges to cure through better and curing sections if needed.
David's option is one viable solution.

First, i would try lowering your unit to 2 inches from the garment to reduce heat loss on the outer edges. You'll need to reduce your cure time, but the ink should cure faster.
I took your advice and lowered the flash and cured for 30 seconds, I was able to check temp to about a third of the way in to the center and on the edge, it reached 330 on the edge and 360 to the center area for thirty seconds. Both test swatches passed pull test and are now on their second test wash, I'll keep my fingers crossed.
Noticed that both test swatches had several glossy areas in the black near the center, didn't affect the pull or wash test but I haven't done my last wash test and dried to check but is this glossy effect normal in random spots or should I increase my time 10 seconds or so and try to make this effect uniform? I'm guessing this is the way the finish product should look sense this is gloss black palstisol.
A 15" flash doesn't cover half of a 16" square design, you would have to flash 3-4 times.

edit: nm, misread.
A 15" flash doesn't cover half of a 16" square design, you would have to flash 3-4 times.
It's the flash that's 16X16. His design is 15X15.
Thats correct but I think he is on point with the size issue, I will lay the print out in a quadrant so I can move the garment to each section to reach temp, it will then cover/cure the entire graphic. It will take longer to cure put until I can afford a dryer or invest in the heat press which I plan to do first, it is what it is. The second swatch passed all tests, and I put it through the mill, 3 washes with other swatches and on very hot wash, full on high heat dry and three more washes, I think the unit being warmed more before flash cure was the big difference between the two.I am setting up to run two more swatches now and preheating the flash. Got to be ready by Saturday for the market. The lowering of the unit did work on one of the first two but I will raise it back to 8 inches to do the four part cure so I can check temp as I move the garment and I will cure each section for 30 seconds on the first and 15 on the second per section at 330, then run a full battery of test on both swatches.
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Well I tried something off the wall, had some 12 x 12 granite tiles from a home project so I laid them out at my cure station and raised the flash to 3 inches so I could monitor the heat, moved the swatch once corner to corner rather than three times for a quad pattern, this allowed me to reach 340 max for 1 min per 2 areas. Got a smooth glossy finish all over the graphic, and I am currently cooling for the wash tests, I hope the granite held the heat from below providing a more uniform heat pattern. here is the first swatch will try 100 percent cotton next if all tests pass, forgive the photo its a little out of square


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Well cure test was a success on the scrap 100 cotton t, 6 washes on hot and 2 high heat tumble drys and no graphic detail loss. I do see a little graininess to the red and black, slight rough texture and the plastisol was taking a second to release from the screen so I will mix throughly and add a little reducer to smooth the ink if needed so it doesn't want to pull at the screen. I've been careful to flash and cool before the next coat so I don't think thats what's causing this small issue.

First print tomorrow and I will be running all of them tomorrow if I can, might need a extra day to finish, I'm not that fast and since I only have a single color press all of the 2 or 3 color shirts were registered on the screens so I have to swap screens as needed.

Only 2 of the 5 shirts have more than 1 color and these are on the front, but the other 3 have front & back graphics, 2 have pocket graphic with a full size back graphic, and 1 has front and back full size graphics but they are 1 color per side on each. I can just print all second sides after I cure the first side.
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the thermostat was busted on my buddies dryer. His shirts were comin gout over 450 degrees. no scorching on whites or any other color. Dont be afraid to go over 330, 360, etc. Just turn it up to make sure the ink gets heated enough.
thanks, I don't have a thermostat on this one, someone said something on a post about a granger unit. will something like this allow me to control temp or am I going to have to use work arounds till I upgrade
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