I have sandblasted the chassis of my restoration project. The accessible areas I had planned to coat with extreme chassis black primer and extreme chassis black, but the frame is a closed channel for most of it’s length with limited access (2″ holes spaced about 10 inches apart on the inside of the frame). One stretch in particular is closed for about 18″ on both rails after some custom welding I did, and is accessible only from one side. Before closing that area off, I had sandblasted the inside of the channel the best I could, but I know some rust still lingers.
My question is the best way to reach this enclosed area to apply a protective coating…I’ve heard of some people using a toilet brush on this kind of vehicle. I thought I would maybe try this with rust encapsulator just on the inside of the frame, and still use the extreme chassis black primer and extreme chassis black on the rest of the frame. There also is an undercoating system available that says it can reach hard to reach places (item #16003) but that seems only to be for Antirust and Undercoating, not Rust Encapsulator. Any thoughts on a better way to go about this?