This is probably the biggest problem for people who are starting to use or are changing over to water-based inks, particularly from plastisols, which are very forgiving in this regard.
Prevention is better than cure, so if you can, keep humidity in the print area above 40-50% RH.
When people first start, they can use a fine mist of water every 15-20 prints to maintain the moisture of the inks. Many people swear by this method. The most important thing is to flood the screen with a layer of ink (1-2 mm; 1/16-1/10”) and to keep the ink moving. If a screen has been sitting around doing nothing for a while, pull a test print from it onto a scrap t-shirt or piece of fabric.
If the ink does start to dry in the screen a little, don’t panic. Just pull a print on a test piece, so that as much ink is cleared from the mesh as possible, take a damp rag and clean both sides of the screen, then remove excess moisture with another rag. Reflood the screen, take another test print and then you’re good to go again.
Mesh count is often a factor. The higher the mesh count, the quicker the ink will dry. Most garment printers use a 43T (110 tpi) mesh.
Use a good emulsion that is compatible with water-based inks and maintains its integrity and you can get good results even with a coarser mesh. With increased experience, you will eventually master 77-90T (195-225 tpi) meshes for SUPERCOVER and up to 120 T (305 tpi) for PERMASET AQUA and PERMATONE.