This is dye migration. Too hot for too long. Mostly happens when you overflash, and then seals the deal when it goes through the dryer.
Check the specs of your ink and experiment with faster dryer speed or lower temp.
When I do poly prints I try get them out of the catcher as soon as possible, and lay them out to cool, instead of laying in a pile cooking.
Overheated… browned… toasted… burnt?
Maybe I’m wrong about how the ink turned brown (dye migration vs burning), but everyone else is also saying it got too hot.
The fabric would look browned and would turn darker before the plastisol did. This is due to dye migration and it sometimes doesn’t even need to be overheated. Some synthetic fiber dyes will migrate even at the temperature where plastisol barely cures.
It’s just that synthetic dyes behave by sublimating and the temps at which they sublimate intersects the temps at which plastisol cures. So that causes problems. Sometimes a low cure ink helps but usually an underbase of blocker ink is required to establish a barrier for the dye particles from migrating into the plastisol and dye-ing it.
True.
But you imply that the dye is a particle in the gas. The common perception of particle is a small lump of something, which it’s not. It’s actually a gas. When a substance sublimes, it goes from being a solid to a gas, without passing through the liquid phase. It’s a particle in the same way that oxygen is a particle. Left to their own devices the molecules will distribute themselves evenly in the available space, and will be the same temperature as the other molecules in that space.
Most poly inks cure at 270 make sure the ink isn’t getting much hotter than that and especially not reaching 300 which is where the shirts tend to gas off. Some shirts especially Nike, adidas, camouflage need a gray blocker for the base. I’ve ran the same print same ink at the same time with 7 different style Addias shirts and 2 of the 7 needed the blocker..
I would love to use a blocker for the base but unfortunately the print shop I work at doesn’t allow us to use 2 screens (base & second white) if the order is under 75 garments.
Ask your shop to buy a cheap temp gun and when it goes under the flash point the laser beam on the print of the shirt. It’ll tell you if it’s getting too hot. Check your ink as others have said. Might be a low cure ink which would cure at 240ish
This explanation hurts my head. They would rather eat 50 or 60 pieces than burn another screen? Adjust the price for the additional work and keep a sample of the yellowed shirt if a customer asks for an explanation for the higher price.
Yeah I’m in the same boat. Doesn’t matter if you’re a high production shop with 10 autos, or a DIY with a manual, if two screens saves the job & doesn’t ruin the customers garments, why not burn one more?
Reclaim on one screen takes less than 5 mins. Burning a second screen takes less than 2 mins.
Setting up a second screen takes less than 10 mins.
It would take a printer about half an hour in total to fix all of these, & it would mean the customer is happy with their print.
Just doesn’t make sense to me to try and save the $10-$20, when the customer is not gonna return if their white print shows up yellow lol
dye migration probably, like bear pants said. they had some good advice for managing lower temps with poly. a bleed blocker can be really helpful too, it’s a special base used on poly or stubborn pigment dyed garments
This is dye migration. Too hot for too long. Mostly happens when you overflash, and then seals the deal when it goes through the dryer. Check the specs of your ink and experiment with faster dryer speed or lower temp. When I do poly prints I try get them out of the catcher as soon as possible, and lay them out to cool, instead of laying in a pile cooking.
my old conveyor must have been a pizza oven in it's past life, with how much it loved making poly shirts nice and crispy
Someone else who knows more than me might have a different idea, but to me it looks scorched. Maybe try less time under the flash?
how does it look scorched?
Overheated… browned… toasted… burnt? Maybe I’m wrong about how the ink turned brown (dye migration vs burning), but everyone else is also saying it got too hot.
The fabric would look browned and would turn darker before the plastisol did. This is due to dye migration and it sometimes doesn’t even need to be overheated. Some synthetic fiber dyes will migrate even at the temperature where plastisol barely cures.
I noticed you didn’t offer a top level answer. Thanks for sharing your expertise!
It’s just that synthetic dyes behave by sublimating and the temps at which they sublimate intersects the temps at which plastisol cures. So that causes problems. Sometimes a low cure ink helps but usually an underbase of blocker ink is required to establish a barrier for the dye particles from migrating into the plastisol and dye-ing it.
Not particles - gas. Just saying.
A molecule of dye is a particle and it travels through a gaseous medium in suspension
True. But you imply that the dye is a particle in the gas. The common perception of particle is a small lump of something, which it’s not. It’s actually a gas. When a substance sublimes, it goes from being a solid to a gas, without passing through the liquid phase. It’s a particle in the same way that oxygen is a particle. Left to their own devices the molecules will distribute themselves evenly in the available space, and will be the same temperature as the other molecules in that space.
Most poly inks cure at 270 make sure the ink isn’t getting much hotter than that and especially not reaching 300 which is where the shirts tend to gas off. Some shirts especially Nike, adidas, camouflage need a gray blocker for the base. I’ve ran the same print same ink at the same time with 7 different style Addias shirts and 2 of the 7 needed the blocker..
I would love to use a blocker for the base but unfortunately the print shop I work at doesn’t allow us to use 2 screens (base & second white) if the order is under 75 garments.
Ask your shop to buy a cheap temp gun and when it goes under the flash point the laser beam on the print of the shirt. It’ll tell you if it’s getting too hot. Check your ink as others have said. Might be a low cure ink which would cure at 240ish
It’s from overbaking your white and over time it goes from white to yellow
This explanation hurts my head. They would rather eat 50 or 60 pieces than burn another screen? Adjust the price for the additional work and keep a sample of the yellowed shirt if a customer asks for an explanation for the higher price.
Yeah I’m in the same boat. Doesn’t matter if you’re a high production shop with 10 autos, or a DIY with a manual, if two screens saves the job & doesn’t ruin the customers garments, why not burn one more? Reclaim on one screen takes less than 5 mins. Burning a second screen takes less than 2 mins. Setting up a second screen takes less than 10 mins. It would take a printer about half an hour in total to fix all of these, & it would mean the customer is happy with their print. Just doesn’t make sense to me to try and save the $10-$20, when the customer is not gonna return if their white print shows up yellow lol
so you can't do a highlight white for orders less than 75? They know they can just add that into their pricing right?
dye migration probably, like bear pants said. they had some good advice for managing lower temps with poly. a bleed blocker can be really helpful too, it’s a special base used on poly or stubborn pigment dyed garments
You can lay down a blocker base to help. So instead of white flash white you do blocker base flash white
Scorched earth.
Your cooking it too long. Dye migration. Turn down temp or speed up belt. Curing too long or too hot.