It was clear from the start. There's the sublimation we want and the sublimation we don't want. How do they differ, you ask? Very simple.
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When we work with 100% polyester garments and use the sublimation technique to decorate them, we want it to work.
The problem arises when we DON'T WANT there to be sublimation. This happens when we use - for example - sweatshirts or softshells and print them with screen printing or flex printing. In this case, sublimation (also known as dye migration) is our biggest nightmare (and that of any print shop). I once remember one of our partners ruining 400 sweatshirts in a single production because the garments were sublimated.
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That's how you know something is sublimating;
- Imagine you're printing white on a black shirt. You know there's sublimation when the white ink turns grey (a mixture between the colour of the shirt and the ink you've applied);
- Imagine you're printing white on a red shirt. You know there's sublimation when the white ink turns pink (a mix between the colour of the shirt and the ink you've applied);
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In English, this problem is called "dye migration" precisely because there is a migration of the dye from the shirt to the print. It's a chemical reaction that is practically uncontrollable.
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The worst?
It can come up at any time; we've had situations where shirts have left our premises in perfect condition and sublimated on the way to the customer's address. Another situation in which the shirts sublimated a week later. It is essentially uncontrollable from the moment the garments are produced.
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So how do we avoid something we can't control? In a word, prevention. In four words, learning from experience.
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And that's what we actually did. After a series of discomforts with this problem, we looked for a paint that would permanently solve the situation we were in - a sublimation blocker. We initially used a grey base underneath all the prints, but soon realised that not only was it robbing us of a machine head, but it was also increasing the thickness of the screen print.
So we went in search of a new option; after a few years of research and testing, we found a WHITE paint that already has the blocking agent included. This way we can print faster and with less ink deposits.
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Another solution was to reduce the temperature of everything we work with. Between colours we need to use flashes, a very large amount of heat and in a very concentrated way so that the paint is no longer so liquid. What did we do? We tested different temperatures until we found what worked for us.
We have found a solution that cools the print very quickly after the flash. It's a machine that sits between two heads and activates a spray gel that cools the prints. This often avoids having to turn the jerseys round again and allows you to gain another pallet.
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Finally, we have also reduced the temperature of the oven as a safety precaution, thus preventing sublimation in 99 per cent of the jobs we currently produce.
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For us, these solutions have worked, but we know that there is no definitive solution to the problem. It's actually a problem that's been getting worse over time as jumpers are increasingly made of more polyester. Also in 2019, Mukua - which also has a print shop - changed the composition of its shirts from 80 per cent cotton to 65 per cent cotton, which still isn't bad given that the industry mainly uses 50 per cent cotton shirts. Technically - and naturally - the lower the percentage of cotton, the lower the quality of the work on the shirts and the greater the likelihood of problems with the print.
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We hope you've been enlightened by this more technical question - and answer.
