Dave Roper, MD of Screen Print World, explains how to guarantee great results when screen printing on sweatshirts

The most common question that comes through to Screen Print World’s ‘Screen Printing in the UK’ Facebook page, according to Dave Roper, the company’s MD, is ‘Why can’t I print properly on a sweatshirt?’. Dave agrees that screen printing on a sweatshirt would seem to be pretty straightforward, yet the thicker fabric, texture of some sweatshirts, and the different types of ink required can easily cause problems. The higher price of a sweatshirt compared to a T-shirt also means that mistakes can prove costly.

“Printing on sweatshirts is a good technique to master precisely because it’s an area of screen printing which many printers shy away from,” he says. “It’s easy to fall into the trap of sticking to what you know, but with new skills come new opportunities. It’s another string to your bow, and a very easy way to increase the number of customers who may wish to use you for a job.”

Once you’re armed with a few tips and tricks, there’s no reason why printing on sweatshirts should be difficult. “Using low temperatures (flash curing) is crucial, as polyester/cotton blends are susceptible to shrinking under heat,” explains Dave. “Pallet adhesive is mandatory – securing your garment in place is essential for maintaining a sharp registration and a crisp print.” Most sweatshirts now contain polyester, so it’s important to check the label so that you can use the correct ink choice. “When you print on a polyester blend, the dye can release out of the garment. This is known as dye migration, and you need to use an anti-blocking agent to prevent this when printing.”

This hoodie was printed in the Screen Print World’s Print Academy, using the new M&R Diamondback E all-electric screen printing press, with Saati Hitex 62/156 mesh and a static aluminium frame. Dave used 7022 Cool White from International Coatings to achieve a brilliant opaque white and cure at a low temperature. At least 15 newtons is needed for good screen tension and the flash cure was set around 100°C, which is enough to touch dry the ink but not cure it, reducing the chance of misregistration caused by shrinkage of the garment.

www.screenprintworld.co.uk

Step-by-Step: How to screen print sweatshirts

(1) Establish the material: we’re using a B&C unisex hoodie (WU620) made from 80% cotton and 20% polyester, and we’re printing on the back

(2) Use spray adhesive to give a nice, even coat of glue and ensure the garment doesn’t move

(3) Stroke the garment fibres away from you (same as the print direction) to give a flatter surface and reduce the risk of the garment moving while printing

(4) As sweatshirts are much thicker than T-shirts, you need to set the off-contact to around the thickness of a pound coin. This creates more space between the screen and the garment, which gives you a nice, crisp print and prevents the ‘orange peel effect’

(5) Flood and push print. You need at least 15 newtons of screen tension on a standard static aluminium screen. The objective is get the ink to release from the flooded screen onto the garment below. If there’s not enough tension on the screen the ink will sit in the mesh and not snap back when printed. This means it will only release the ink when you lift the screen, which won’t give a smooth finish

(6) Set flash at the lowest temperature to reduce the chance of misregistration caused by shrinkage via over-heating

(7) Ensure that there’s an opaque finish. If not, print again as flashing allows a second layer of ink to be adhered to achieve the opacity you need for your customer

(8) Check for quality

(9) The end result – a perfectly printed sweatshirt