[question 1]
border between original factory paint and POR-15 or Rust Bullet, etc.

I would like to know how POR-15 or Rust Bullet behaves with existing car paint.

I do not want to apply POR-15 or Rust Bullet on the whole panel because of some small rust areas on the panel.

The rust area I want to repair is surrounded by car's factory paint.

So, if moisture or other harmful things penetrates at the border of POR-15 or Rust Bullet and car's paint, rust area will grow again.





[question 2]
Did anyone compare POR-15 and Rust Bullet?


I did some work with POR-15 starter kit.
It took quite a long time: Marine Clean -> wash -> dry -> Metal Ready -> wait 15 minutes -> wash -> dry -> POR-15 -> wait -> second coat of POR-15.
After 3 days: fine sandpaper, and then apply touch up paint.

I heard good things about POR-15 from end users, but heard nothing about Rust Bullet from any end user yet.