Mechanic’s UV Solder Mask
UV curable solder mask is a special type of resin that hardens when exposed to ultraviolet light. It comes different colors in a syringe type tube.
Solder masks resist solder and act as a protective layer that rests on top of the copper traces. It’s the green stuff found on most common PCBs. Solder masks can take high temperatures, so it can handle the intense heat from the tip of a soldering iron.