I would not use anything water based if spraying. You’ll have a drying issue. You may want to try Dykem, an ink based layout fluid that machinists use on steel and aluminum. It’s fairly dark in red or blue and can be sprayed full strength or watered down with denatured alcohol. It also looks pretty good over chrome exhaust pipes creating that hot tint hue. Be sure to clean your painting surface first. Dykem can be purchased many ways through MSC, McMaster Carr, Grainger, Amazon or EBay. Good luck.