When ink is drying in the screen during a production run, it is most likely caused by the platens heating up excessively. This is a tricky problem as you may be underbasing with white ink or even two screens of white ink. A cool down station may be necessary cool the print and stop the ink from heating up in the screen. If you want to continue with a very fast production, you can try the Production Series inks by One Stroke Inks. These inks will flash and lose their tack in half the time of normal plastisol ink. This keeps the platens cooler and allows production to keep moving. Production Series can help you on cotton, poly/cotton, nylon, and polyester. If you do not want to change inks, test the flash and get it to the quickest possible flash time that you can without the ink remaining wet or tacky. If the ink drying problem is not related to production and you are simply leaving ink in the screen overnight, simply clean the screens at the end of the day. Most inks will clog the mesh when left for this long. Also, you open your screens up to the risk of excessive hazing problems.