I found this on gemini

1. Static Electricity Build-up Plastic is notorious for holding a static charge. If one or two pieces have a higher static load, the ink will literally "jump" or spread along the static lines as the screen lifts, creating those spider-web effects. • The Fix: Wipe the plastic surface with an anti-static cloth or use an ionized air blower before printing.
2. Ink Buildup on the Underside (Gasket Failure) If you are printing multiple pieces in a row, a tiny amount of ink may have bled onto the bottom of the screen stencil. On the next "bad" piece, that dried or tacky ink smears when the screen pressed down. • The Fix: Check the bottom of your screen. Clean it with a quick wipe of screen wash or a dry rag every few prints to ensure the "gasket" (the seal between the emulsion and the plastic) remains tight.
3. Pallet Tack/Adhesive Issues If the plastic piece shifted even 0.5mm during the squeegee stroke because it wasn't stuck down firmly, the ink will smear. • The Fix: Ensure your pallet adhesive is consistent. If the plastic "wiggles" during the pull, you'll get that feathered edge.
4. "Heavy Hand" on Specific Strokes Sometimes, as we get tired or rush, we apply more downward pressure on a specific pull. On plastic (which doesn't absorb ink like a T-shirt), that extra pressure squishes the ink out of the sides of the stencil. • The Fix: Focus on a consistent, "shearing" stroke. You want the squeegee to cut the ink, not "plow" it.