Rock ding, Rust prevention question

Got a rust prevention question for you guys.

I was driving behind a dump truck and a huge rock hit my roof. It left a gash in the paint, all the way to the bare metal.

I bought a paint pen from the dealership. Should I clean or coat the bare metal with anything, before I paint the gash in?

 

Just clean it with a little alchohol and use your paint pen. Won't be an issue

 

Why use alcohol? If it is a mild steel surface that might start corrosion I would think.

 

Prep is always key when painting, You use 70/90 alcohol to make sure the metal is clean before adding paint. Look it up on YouTube’s. Your choice if you wish to buff it as well.

 

Cool, good to know.

 

I am, total noob question. What is 70/90 alcohol???

 

Maybe drop a spec of spot filler on there then color over...

 

70% or 90% isopropyl alcohol, you can find it any where ...Wally world, any drug store