6. Clean your plate

Mineral spirits will strip the ground off of your plate.  Use gloves.  Check in the red hazardous disposal can in the letterpress shop, see if there are any clean-ish rags in there, and then get a tiny dap of spirits from the red pump container.  Should be easy to wipe the ground off.  Always put spirits rag back in the container, they are flammable when exposed to air and it’s bad to inhale.