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Discussion Starter · #1 ·
i'm running both my flash dryer and conveyor dryer off of a generator, so to save power and tripping, i decided to flash dry all my shirts first, then run them all through the conveyor dryer non-stop. however, i noticed after the fact, that some parts of the print where cracking when pulled apart. i'm not sure if my design was too big and the flash dryer didn't cover it on the pallet, or if when i ran it through the conveyor dryer, that part of the print wasn't under the heating element. any suggestions? and is it possible to continue drying the way i did it? (flash first then conveyor dryer all at once). thanks
 

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Whoa. Lots of variables here. GENERALLY speaking, cracking is a result of under cured plastisol. Take a look at where the cracks are occurring. If it's on the edges of the design then your design is indeed too large for the coverage area of the flash and/or conveyor dryer. If it's hit-and-miss, you're just not getting that ink layer up to temp.

Now I'm not going to get on you about flashing everything and then running through a conveyor dryer as you seem to have limited options. As long as the ink isn't coming off on the other shirts as you stack/store them for their trip through the conveyor dryer, I'd say that it's not the flash that's the culprit (it's doing what you want it to do, namely cure the ink enough to keep it stable until you can cure it properly).

The main culprit is probably your conveyor dryer. Plastisols need TIME and TEMPERATURE to cure fully. Just getting the ink layer up to cure temp isn't always enough depending on mesh count, ink viscosity, additives, etc. You need some "dwell time" to bring the entire layer up to cure temp. My first suggestion *without knowing what sort of equipment your running* would be to slow down the belt speed. Might want to do a few wash tests to get everything dialed in as well.

More information from you might help figure out your issues in depth:

Shirt color
Imprint size
Mesh count
Ink used
Design size
Type of flash
Type of conveyor
etc.

:)
 

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Discussion Starter · #3 ·
thanks! maybe i have to run it through the dryer twice? it's a small one, like 5 feet long. i do have it on the slowest belt speed. do you think i need to buy a temp gun?





Whoa. Lots of variables here. GENERALLY speaking, cracking is a result of under cured plastisol. Take a look at where the cracks are occurring. If it's on the edges of the design then your design is indeed too large for the coverage area of the flash and/or conveyor dryer. If it's hit-and-miss, you're just not getting that ink layer up to temp.

Now I'm not going to get on you about flashing everything and then running through a conveyor dryer as you seem to have limited options. As long as the ink isn't coming off on the other shirts as you stack/store them for their trip through the conveyor dryer, I'd say that it's not the flash that's the culprit (it's doing what you want it to do, namely cure the ink enough to keep it stable until you can cure it properly).

The main culprit is probably your conveyor dryer. Plastisols need TIME and TEMPERATURE to cure fully. Just getting the ink layer up to cure temp isn't always enough depending on mesh count, ink viscosity, additives, etc. You need some "dwell time" to bring the entire layer up to cure temp. My first suggestion *without knowing what sort of equipment your running* would be to slow down the belt speed. Might want to do a few wash tests to get everything dialed in as well.

More information from you might help figure out your issues in depth:

Shirt color
Imprint size
Mesh count
Ink used
Design size
Type of flash
Type of conveyor
etc.

:)
 

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Plastisol needs to reach 320 for 30 seconds for full cure unless your using fast fusion.Put the shirt on the belt and make sure it's in the chamber for that length of time.Make sure the print is FLAT and faces the IR panels for full exposure.If the prints not flat in a electrc dryer the peaks will cure but not the valleys.
Temp guns are really cheap now or you can use temp strips Also loading up the chamber will drop the intrenal temp.The dryer just can't recover enough heat fast enough.So if the first one cures the ones in the middle might not.So try to space them out when you run them through.Your just working with a little guy dryer.
Test before,during and after.Thats my rule at least.
 

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Discussion Starter · #5 ·
so is it possible to cure my cracking shirts by running it through the dryer again or by putting it under the flasher again?
 

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if your shirts are cracking you can fix the cracking shirts or save them by using a heat press. then go back and adjust your setting to make sure you are curing all your shirts correctly.
 

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you can just cure them again making sure this time that they get to temp long enough. no heat press needed.
 

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he can but if the ink cracked too much the heat press can reheat the ink and bond it back with no cracking ever visisble. im just saying just in case to save the shirts that have been messed up so far. but true adjust your settings going forward.
 

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Absolutely! The only way they would'nt is if you put too many additives in your ink, like extender.That throws off the balance of a stable ink.
 

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Discussion Starter · #10 ·
actually, i did put extender in my white. i've had problems before with white being so thick and my print gets lumpy. does anyone else out there have the same problem and use softhand extender?


Absolutely! The only way they would'nt is if you put too many additives in your ink, like extender.That throws off the balance of a stable ink.
 

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he can but if the ink cracked too much the heat press can reheat the ink and bond it back with no cracking ever visisble. im just saying just in case to save the shirts that have been messed up so far. but true adjust your settings going forward.
You're right, this is a good suggestion. Not guaranteed to work, but it's definitely worth a try as it does sometimes.
 

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Are you doing 2 coats of white flashing between prints? Make sure you are not fully curing the ink before you make you second pass, that will also cause the ink to crack.
 

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Discussion Starter · #13 ·
yeah, i print white, flash, then print again in order to make the white bright enough. i flash for only a few seconds to make it dry to the touch. you're saying that if i flash the first white coat for too long, then it will crack after i put the second coat on?


Are you doing 2 coats of white flashing between prints? Make sure you are not fully curing the ink before you make you second pass, that will also cause the ink to crack.
 

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you're saying that if i flash the first white coat for too long, then it will crack after i put the second coat on?
Yep, if the first coat is cured (rather than gelled) then when the second one is printed, the second won't be able to adhere properly to the first. Flashing it too long could cause a full, rather than partial, cure.
 

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Printa Systems recommends 350 for 30-45 sec/
Using a flash dryer now, until I can get a Conveyor
Waiting a bit long scorches some shirts. Is 350 too hot or do I have this wrong?
 

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Whoa. Lots of variables here. GENERALLY speaking, cracking is a result of under cured plastisol. Take a look at where the cracks are occurring. If it's on the edges of the design then your design is indeed too large for the coverage area of the flash and/or conveyor dryer. If it's hit-and-miss, you're just not getting that ink layer up to temp.

Now I'm not going to get on you about flashing everything and then running through a conveyor dryer as you seem to have limited options. As long as the ink isn't coming off on the other shirts as you stack/store them for their trip through the conveyor dryer, I'd say that it's not the flash that's the culprit (it's doing what you want it to do, namely cure the ink enough to keep it stable until you can cure it properly).

The main culprit is probably your conveyor dryer. Plastisols need TIME and TEMPERATURE to cure fully. Just getting the ink layer up to cure temp isn't always enough depending on mesh count, ink viscosity, additives, etc. You need some "dwell time" to bring the entire layer up to cure temp. My first suggestion *without knowing what sort of equipment your running* would be to slow down the belt speed. Might want to do a few wash tests to get everything dialed in as well.

More information from you might help figure out your issues in depth:

Shirt color
Imprint size
Mesh count
Ink used
Design size
Type of flash
Type of conveyor
etc.

:)
Excellent post @)
 

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Good morning

Plastisol needs to reach around 320 F. the thicker the ink the longer it takes. The complete ink film needs to reach the 320 mark, from top to bottom. Think of it like a cookie or cake. Time is your best friend. You can pass the shirt several times through the oven but if the ink film never reaches 320 F then it will still crack. Please only gel the ink beteween prints or you could experience intercoat adhesion issues where the ink make peel apart.

Let me know if I can help you further.

Here is a link to some articles regarding ink cure.

Hope this helps.

curing | Search Results | International Coatings Blog
 
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