I am a little confused about what is necessary to coat a frame.  I am planning on using the kbs clean, rust blast and then the Rust Seal.  Is the Rust Seal enough or do I need to follow it up with the blacktop?  Also, what is used to get the product inside the frame rails where it is boxed in?  I am planning on brushing on the product to a frame that has the body on the frame.  I am also going to be coating the underside of the body, do I need to use a secondary product (ie: blacktop) on this as well?

another question, will the kbs clean or rust blast damage rubber hoses, brake lines, etc under the vehicle?

As far as topcoating RustSeal, it all depends on your vehicle. If you have parts of the frame that will be exposed to sunlight, you will want to top coat those areas with BlackTop. If the entire frame will be covered by the body, you do not need to cover the RustSeal with the BlackTop.

The Cavity Coater is used inside boxed in Frame Rails because it requires no prep. Coat the outside first with RustSeal (an maybe BalckTop) and then do the Caity Coater on the inside of the frame rail.

Please check out the Cavity Coater DIrections.

Please let us know if that helps and if you have any additional questions.