not too bad, you use like a teaspoon for the whole backside of the lightning 480. Before I was heating the pcb, I tried this stuff with nothing on the backside and water was dripping and there was frost everywhere and card never shorted
Wipes right off with cotten swabs, its not greasy, not sure if its petroleum based but its like more waxy than anything. Would be like smearing chapstick on your counter than wiping it off with a towel.