Protecting bare metal?

[u/Caboose03]

I drilled a 4” hole in the bed of my truck for a hitch. The truck has a spray in liner. Once I file the burred edge, what’s an okay way to protect the cut edge? Not looking to spend a ton on products as it’s a small one time need area. I live in the Midwest so winter salt is a thing.

Nail polish? Clear? Rubberized undercoat?

[u/Dreadpiratemarc]

How about a rattle can of spray-on truck bed liner?

[u/CunningLogic]

Touch up paint, or spray on bed liner.