50/50 blend question

[Appstro]

I am doing a run of 250 shirts for a construction company. They want the Gildan 2000 Ultra Cotton "Safety Yellow" shirts so I say OK no problem. They are 50 cotton 50 polyester. Well I screen printed the shirts with grey and royal blue (just purchased new ICC) ink. Then ran them through the little buddy conveyor which has been checked at 320 degrees. I did a wash test and the grey is holding very well. The royal blue on the other hand is coming off a little and if I do a stretch test on the color it separates. I am not sure if this is to be expected or if I can do something to these shirts, like heat pressing them, to save them from being returned.   Any idea whats going on here? Thanks for your time and all responses appreciated very much!

[Denis Kolar]

Re-run them again, target 340 degrees.
If your gray was low bleed, and I believe it was, you should be OK as far as the dye migration.

[Frog]

I am not sure how the Little Buddy heat control is calibrated, but what was checked to be 320?

Like DK suggested, rum 'em through again a little higher.

Also, for the future, IC does offer an additive that lowers the cure temp a bit.

[Appstro]

Hmmm. The grey is just a color I mixed. Black and white.... Do you think the color will migrate? I see nothing in the wash test.

The little buddy is a set temp but I can control the belt speed. I checked the temp using test strips and also a heat temp gun. The test strips turned completely black indicating that the temp got over 330. The heat gun shows anywhere from 250 to 340 and fluctuates wildly.

One thing that has just occurred to me is that the grey ink is thicker than the blue ink, but not sure if that even matters all that much. I am going to do another wash test on some cotton shirts of different colors in the same run to see if there is also an issue with them..

What about heat pressing them? I have an assistant helping me that could just throw a shirt on at 340 for 5 seconds or so. Would that be enough?

[Denis Kolar]

Heat pressing would work too.
Use kraft paper on the top to prevent the shine.

[Frog]

Did you place the heat strips on the inside of the shirt?

You're probably fine if not, but did you use a low-bleed white for your gray? It's something you'll need in your arsenal anyway.
(Even if not, the added black will help mask a little dye migration, and besides, plenty of grays have a slight color component as well anyway.)

Yes, the heat pressing should also help, but really can't do much more than sending them down the belt again. You shouldn't at 340, but if you get any ink offset onto the kraft paper, make sure to not transfer it to the next shirt.

[tonypep]

Try an LCA additive.

[Appstro]

Thanks guys. Whats an LCA additive?

[Frog]

Thanks guys. Whats an LCA additive?

The Low Cure Additive I mentioned as well. (of course, if the "A" stands for additive, then it's either LCA, or Low Cure Additive, not Low Cure Additive Additive, (like VIN number, Vehicle Registration Number Number, LOL!)

[Appstro]

Got it. These test strips go inside the shirt? I thought they just went on top...

[Frog]

Got it. These test strips go inside the shirt? I thought they just went on top...

On top does not take into consideration the thickness of the ink film, down to its bottom.
Inside the shirt tells you (as well as test strips tell) how hot it got just on the other side of the bottom of the ink deposit.

You will now run into one of their (many)inherent problems in that this is best on a thin shirt.
Obviously it ain't going to be the same on a 12 oz. sweat!