Needs a little CP action though, right?
Bonus points if Wet paint would also rub off on things the artist touches (i.e. wields) for a duration of time.
Also thermographic paint could be utilized on clothing or a person directly for a dramatic increase in there ability to be detected via thermographics plus adding "radiant" to there room short desc.
Maybe thermographic paint can only be made by chemists but doesn't request a lab. Just a can of spraypaint and something else. Naturally, thermographic spraypaint would be invisible to the naked eye on locations. And thermographic paint grenades for obvious reasons.