Terror-free tri-blend T-shirt prints

Follow Marshall Atkinson’s expert advice and wave goodbye to dye migration, shrinkage and scorching on your tri-blend prints

Tri-blend. Have you noticed that this style is dominating T-shirt sales lately? The fabric, as the name suggests, comes in percentages of three sourced materials. Cotton and polyester usually make up the largest portion, but there can also be rayon or modal to make up the third. And, for the sustainability-minded, yarns can be recycled or organic too.

But with that vast array of offerings from the shirt manufacturers comes a wide assortment of production challenges too.

Tri-blend dye migration

Dye migration is also called bleeding. The number one thing to understand is that this problem begins by overheating the polyester content of the shirt fabric. When the shirt was made, dyes were used to colour the polyester yarns to match whichever hue the manufacturer wanted for the garment. For tri-blends, these yarns are woven into the fabric with the cotton and the third material. If heated during your production process to the right temperature, the dye in the polyester content of the tri-blend fabric will change from a solid state to a gas and migrate up into the ink. Murphy’s Law dictates that this won’t happen while you are printing the shirts, but later, after the job has been boxed up and is on its way to a customer: when they open up the box, the white ink has taken on a pastel form of the shirt colour. And not in a pretty way.

Any fabric with polyester content that has dyes susceptible to heat can produce unwanted dye migration characteristics. Red seems to be the worst actor in this scenario by far, but any dark dye can bleed into the ink when exposed to too much heat.

How to prevent tri-blend dye migration

The obvious answer is to control the heat during the process.

Use ‘low bleed’ inks that are made to cure at a lower dryer temperature. Instead of the normal 160°C needed to cure the ink, low-bleed inks cure at about 135°C.

But you shouldn’t stop there. There can be a cumulative effect on your production process with heat. A thicker ink deposit may take longer to flash cure than a thinner one. Compound this problem with a second flash during the production run, and then dog-piling the heat with the dryer chamber, and that jump-starts the problem.

A better way to deal with this issue is to be smart about the design for the shirt, but also the mesh counts used for the screens. Design your graphic to use fewer large areas of lighter colours if you can. As lighter ink colours are more prone to showing the dye migration gas when overheated, using darker ink colours helps to camouflage this challenge from the start.

Higher mesh counts with quality, high-tension screens will transfer less ink onto the surface of the shirt. This will reduce the flash dwell times needed to gel the ink.

Watch your flash dwell times

Also, while we’re on the topic of flash dwell times, many shops think that the flash unit has to completely cure the ink before the shirt can receive the next ink colour in the print rotation. This is untrue. All you need is for the ink to gel and no longer be wet. The dryer will completely cure the ink: the flash unit is designed to keep the already printed ink from smearing during the production process. Over flash-curing is one of the top reasons for dye migration in polyester shirts.

After the just-printed ink is carefully flashed, be sure to then have a cool-down station to give the heated ink a moment to drop in temperature before you add another colour.

Don’t forget about your platens

During a longer production run, the platens on the press can become superheated too. This happens because each time a shirt is printed, the board receives heat from your flash unit. Over time, the platens retain much of that heat. If the flash unit dwell times are not adjusted to a shorter duration, the residual heat on the boards can affect the print and produce unwanted tri-blend dye migration.

Press catcher best practices

The best person on your press crew besides the press operator to control the heat challenges during production is your catcher.

Normally a catcher will grab shirts and start stacking into dozens so they can be folded and placed into a box. Instead of one stack of shirts, try creating four on the table. As the shirts travel down the belt towards the catcher, each subsequent shirt is placed into the next stack of shirts in the row. A fan can be used to blow air onto the shirts to cool them down, and they should not be boxed up until they are cool to the touch otherwise the ink will continue to cook.

Key tips for mitigating tri-blend dye migration

Start with employee training. Discuss the cause and effect of what happens in production with all of your staff.

Avoid art that requires an underbase white if you can, because every flash impacts the outcome. Engineering your print from the art standpoint is the best cure.

Since tri-blend T-shirts are known for their softness, you want to emulate that with the print. Building up multiple layers of thick ink will feel at odds with the softness of the fabric. A better strategy is to use water-based ink or plastisol with some curable reducer added for an extra soft print.

Minimise the ink deposit by using higher tensioned screen frames with higher mesh counts. Use a sharp squeegee with minimal pressure. Your goal is to have the ink kiss the top of the fabric and stay there, so you want just enough pressure to clear the ink from the screen.

Adjust your flash unit dwell times during the print run as the press platens heat up. The dwell times should decrease as the order continues to be printed.

The right hand side of the chest print shows the effects of dye migration on white ink; the ink has taken on a tint of the base fabric colour

Tri-blend discolouration

On some tri-blend shirts, the excessive heat build-up causes the hue of the shirt to darken or brown. Again, this is a dye-related issue caused by heat. The best practice is to control the heat and be careful to not use super-heated platens with long dwell times with the flash.

Tri-blend fabric compression and shrinkage

One common challenge with using a triblend blank is that sometimes the shirt will shrink on the press when exposed to heat. The underbase printed fine, but after flashing the shirt shrinks by a small amount, just enough so that the other screens are not in alignment.

While many printers run the entire order through the dryer to preheat the shirts with the idea that this will prevent on-press shirt shrinkage, the answer to this challenge comes in two steps.

First, make sure the entire platen has adhesive, not just the print area. Apply a thin, even coat to the platen with a foam-roller or a plastic applicator like they use for vehicle wrap applications. Reapply as necessary.

Secondly, watch the heat with your on-press flash units. All you need is for the just-printed ink to gel so it doesn’t pick up with the next colour. You do not need to fully cure the ink. To test, flash cure the print and test it with your finger. Does any ink lift up? Yes? Add a little more time. No? That’s great, but can you drop the time a little still?

Tri-blend fibrillation

The reason why tri-blends have such a huge following is their innate softness. These shirt styles have an instant vintage look and feel like a hug from an old friend. Who wouldn’t want that? Well, anyone who has to print on that fuzzy surface for starters. The problem lies in the cotton fibres that come up through the print and make our work look shoddy.

If you are new to decorating on tri-blends, the best thing you can do is to produce a few test prints on various styles with the same image and see which one performs to your liking. You’ll quickly determine that some styles, after printing and washing, have a distinct, faded and almost fuzzy look.

Tips to combat tri-blend fibrillation

In the print order, place a first-down curable clear base and flash-cure before any colour screens are printed. This will give a good foundation for your print, and lock down the fibres.

Use high-mesh, with good tension. At least a 230 mesh, but a higher mesh count screen might be better. You don’t want to sacrifice the print hand when you solve the fibrillation challenge. Check your ink deposit to ensure it isn’t too thick.

Since the shirt fibrillation problem usually manifests itself after a few trips through the laundry, instead of the clear base screen before the image colours, you might try adding it last. Consider this as putting the force-field on the outside of the print, rather than next to the shirt. This should work just as well. However, this may make the clear ink more noticeable.

Tri-blend scorching

Another common problem with some tri-blend styles is that they can scorch easily. Again, this obviously is a heat issue. Are you noticing a common refrain here?

What causes this is that the air that is between the press platen and the shirt gets super-heated during the flash-cure dwell times. However, what you will find is that where the platen adhesive was applied, the shirt won’t be scorched. For example, if you only applied the platen adhesive around the left chest area, the scorching will be outside of that patch of adhesive.

Tips to prevent tri-blend scorching

Obviously, pay attention to your flash cure dwell times, and use a designated cool-down station after you have flash cured the ink.

As with avoiding shrinkage, make sure the entire platen has a thin, even coat of adhesive and reapply as necessary. Be careful that you don’t apply too much and distort the print removing it from the press platen to place on the dryer belt. You don’t want to solve one problem and then create another.

If you do happen to scorch a few shirts, hydrogen peroxide sprayed through a mister bottle onto the problem area, then back through the dryer, can sometimes remove the problem from the shirt.

Tri-blend shirt conclusion

Tri-blend T-shirts are here to stay and you need to be careful how you screen-print them. This should ideally start with your customer service or sales team: have your customer-facing crew give clear expectations about decorating a tri-blend T-shirt during the sales process. Then, your art department should be able to creatively engineer a print that will work best on this popular blank.

Use good tensioned screens with higher than normal mesh. Your screen room sets up the foundation for the success of the print.

On press, use just enough squeegee pressure to clear the ink from the screen and onto the surface of the garment. If the shirt is prone to fibrillation, print a clear curable base screen first, flash and then print the image on top. That should lock down the fibres.

And, most importantly, repeat after me: Pay attention to the heat.