# Cured ink cracking...



## davejonez (Sep 4, 2009)

Alright, so i'm 9 shirts deep into a 30 shirt project and my white ink is cracking in areas where the letters on the print narrow. This is happening after being cured at 350+ for 1-2 minutes. 

The prints are coming out nice with a 156 mesh screen, it's just that I'm concerned about the shirts longevity. The ink texture almost feels brittle after being cured. The Stretch test is working in areas where the letters are thicker and the cracks are only occurring vertically with the ridges in the fabric after being stretched. The print retracts but I don't like the fact that it cracks at all, it's supposed to be stretchy right?

I'm using gildan ultra cottons and QCM glacier white thinned down with reducer. 

My print technique also goes like this, 4 print strokes, a flash, and one more print stroke, then cure. 

Can anyone help me out with this problem? Is the ink bad?


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## ole Jobe (Jun 16, 2009)

How are you curing, flash unit or heat press? At first glance it would seem that the cure temp, time are not enough. But if the heavier ink deposits are standing the stretch test, they should be cured. The next question would be the flash. If the flash is too long, the thin ink layers may be curing. When this happens, the subsequent layers of ink will not fuse with the cured layer and the ink will crack and peel. God Bless.


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## davejonez (Sep 4, 2009)

ole Jobe said:


> How are you curing, flash unit or heat press? At first glance it would seem that the cure temp, time are not enough. But if the heavier ink deposits are standing the stretch test, they should be cured. The next question would be the flash. If the flash is too long, the thin ink layers may be curing. When this happens, the subsequent layers of ink will not fuse with the cured layer and the ink will crack and peel. God Bless.


I'm using my flash as a curing unit... Today I will try out shortening the flash time even though i'm doing that approximately 20-30 seconds. Thanks for you input and I'll get back to you on the results.


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## jmlampert23 (Nov 7, 2008)

you are most likely over curing the ink which makes it crack


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## hdem (Mar 1, 2008)

Flashing the ink is something that takes only 3 - 7 seconds. Shorter flash time if you are going to print the same color again, longer if you are adding different colors. After you have printed the whole design, it should take at least 30 seconds (sometimes 45) to fully cure the print. If the ink cracks AT ALL while doing the stretch test then it hasn't fully cured. It is true that if you cure the ink too long (2 minutes or longer, which you probably scorched the shirt any how) it can also cause the ink to crack because you made it brittle. It has to reach at least 320 F to also cure, get a laser thermometer gun to check temperatures. Also adding reducer can effect cure times, adding too much can prevent the ink from curing. Reducer is best used in very little amounts 5% or less by weight. Stir your ink very well before printing rather than softening it by adding reducer, that works better.

Good luck.


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## torodesigns (Jun 24, 2007)

Usually you only need to flash for 4 - 10 secs.


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## davejonez (Sep 4, 2009)

thanks for the responses... Well, my flash is an older harco model. The heating element is not infrared and is more like a kitchen oven. I probably am overcuring but doesn't it just jell over instead of dry out? 

I've also got a laser thermometer and i've been pulling some readings of high 300's and low 400's.

I've attached some images to show what I'm talking about...


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## QCM (Aug 27, 2007)

Thanks for the pics Dave.

My first questions is - Do all the thin areas crack? Or just some? If only some are cracking my guess is the flash unit you are using to cure with is not consistent in it's heat output.

When you use the temp gun - do you put it directly over the ink to test or do you shoot it from several feet away? I ask because the further away from the target you are - the less acurate you are. Also please remember that temp guns only give off a reflective surface value. Not the temp at the bottom of the ink layer.

If you have any questions please feel free to give me a call.


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## iCamefromEarth (Jan 14, 2009)

Are they normal t-shirts? If they're really stretchy formfitting things (like girls tanks, or ribbed shirts meant to stretch) you might need to use stretch additive. Probably not the answer on 100% or 50/50 T's though.


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## adivito (Aug 25, 2006)

Looks like you are curing between layers, and not "flashing" which causes the first layer to not adhere to the following.


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## hdem (Mar 1, 2008)

I used to use an old Brown/Harco flash unit that didn't give off equal heat all the way around that would give me curing issues near the edges of my design. I'm thinking you might have added too much reducer or try to add a touch of stretch additive. Always follow recommended directions when using additives so you don't run into curing issues. Also reaching high 300's and low 400's seems way to high, I'm surprised your shirts don't scorch. It should only take 30 seconds on a design like the one in your picture to cure enough. If you're going a minute or longer especially at 400F you will be over curing. Also don't over cure between prints. Hope you figure it out.


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## BillyV (May 8, 2009)

davejonez said:


> This is happening after being cured at 350+ for 1-2 minutes.


You are baking the ink into char, ink just needs to be brought up to 310-330 depending on your ink to properly cure, once the ink reaches the curing temp your done, get the heat off the ink.


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## davejonez (Sep 4, 2009)

adivito said:


> Looks like you are curing between layers, and not "flashing" which causes the first layer to not adhere to the following.



So after doing about 7 prints on the rejects: The flash in between was a bit too long on the first shirts and WAS actually curing the thin layers(thanks for pointing it out guys). The shorter flash time of 5-10 seconds is really helping the final coat form a better bond.

I was also skeptical of overcuring plastisol, but a few tests actually backed it up. Cured for 2 minutes, let it cooled down, then cured it for 2 more. The result seemed to be a more brittle and easily crackable print. gonna do some more testing tomorrow but I think this problem is nearing a solution.


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