Use a lower mesh screen (110) to apply photochromic ink (UV ink), allowing more ink to flow through.Otherwise, the ink lays down very similar to plastisol. You can blend both plastisol and UV inks on the same shirt so that only a portion changes color when it’s exposed to sunlight.
Check your registration. This is important since you won’t be able to see ink as it lays down. With really close registration, use a black light to ensure registration is tight.
Apply plenty of UV ink to the screen. Since you can’t see it when the ink lays down (other than gel color), it’s important to monitor ink in the screen so that you’re not missing a coverage area.
Lower your dryer temperature. Monitor to make sure the UV ink doesn’t turn a light brown/yellow color. This is a sign of ink that’s over-curing.
View the screen print outside to see its uv reaction with actual daylight.
Tip: “UV inks perform best on white 100% cotton shirts,” says Bruce Jolesch, president of Garland, TX-based PXP Solutions. “It’s something potentially used for a special event or an incentive trip going to a beach location. The inks become intensely colored after only 15 seconds in direct sunlight and return to clear after about 5 minutes indoors.”