Plastisol ink has a more glossy appearance. Here’s a good write up about it.
WHAT MAKES A PRINT LOOK GLOSSY
Glossy prints have a smooth surface where the ink sits on top of the shirt. Light is able to reflect off the ink’s surface, which makes it look more glossy.
Laying down a heavier ink deposit will also make a print look glossy. The heavy ink deposit will not permit the shirt’s fibers to influence the surface texture of the ink. The smooth, flat surface will be shiny once you pull it out of the dryer.
Athletic apparel typically have a thicker ink deposit. Jerseys, hoodies, etc. usually have sheets of plastisol layered on top of each other. Therefore, athletic apparel is much more shiny compared to other kinds of apparel.
Pro Tip: Plastisol inks are usually more shiny compared to water-based inks.
Photo by Lookout Prints.
HOW TO ACTIVELY CREATE A GLOSSY PRINT ON PRESS
Remember, the key to getting a glossy print is keeping the ink on top of the fibers to create a smooth surface.
One way is with printing your base white and using a smoothing screen to get the surface super smooth. Now you can over print the white base, allowing the top colors to be smooth and glossy. Or, you can print-flash-print the colors because the flash will enhance the smoothness of the ink’s surface. Use a smoothing screen to make it even smoother.
LEARN MORE ABOUT SMOOTHING SCREENS
You could also mix in gel gloss to the ink (gel is designed to be glossy and shiny). Or, you could overprint part of the design — or the whole thing — with the gel.
There's one fact that's important to note about inks that are designated as matte: These inks will be very difficult to create or add a gloss to it since the the ink already has dulling agents/additives in the ink. Try adding gel into the ink and testing what works best for you. You could also try overprinting at the end with a gel gloss.
Photo by Symmetree Clothing.
Pro Tip: When printing on synthetic shirts, it’s easier to create a smooth, flat surface because there are no free fibers poking through. If you’re printing on cotton tees, you’ll have to work harder to achieve a flat surface.
Another way to achieve the glossy effect is by curing the print at a higher temperature. Excess heat can affect how the inks look. Running with the heat set high will typically cause the ink to sit at a “melt point” for an extended period of time. Sitting in this high temperature can directly cause the ink to become shiny. It's a viable technique, but not all ink will behave this way unfortunately. Some ink types and brands that will bubble or puff when the ink gets too hot. The print may look mottled. Always test inks before running any kind of production and pick the method that works best for you with your equipment within your shop.
Remember the vintage print? It is possible to make a vintage print a little glossy by using a smoothing screen after a flash or an iron. Utilizing one of those tools will set the ink on top of the shirt, making it more glossy. It’ll still be vintage soft.