Coating inside body panels

[Grrrmachine]

I'm patching up a rusty scuttle on my car, and there'll be a few sections that I won't be able to get to after they're welded. What coatings can I put on them to stop them rusting out in the future?

This would apply to things like the inner surface of sills, which will get wet inside; how are you supposed to protect them? The car had those panels painted from the factory before it was spot-welded together, but I can't replicate that procedure now...

 

[piman]

Hello GM,

difficult to answer for someone in Poland. In the U.K. we have wax based products that can be sprayed into section like sills to protect from future corrosion? What will be available to you?
The panels are not painted prior to welding when the car is constructed but shells are often dipped in paint after welding or more modern cars are galvanised after etc.

Alec

 

[cumbriasteve]

If I was restoring a car I would use something like red oxide pinted on internal surfaces first and then ensure access holes to hidden spaces were left, covered by a grommet which could be removed to allow access for an injection lance using Waxoyl or similar.

I would then treat these areas each year to a spraying.

Something like this http://www.lkperformance.co.uk/Oils/WaxoylHammerite_Waxoyl_Starter_Kit_-_2_5L/247188

I know of a car a friend restored about 12 years ago and he used this method, as far as we can tell it has been a big success.

 

[Grrrmachine]

Yeah, the problem is availability of specific products. I've got hold of some Dinitrol RC900 (the spray-on rust converter), and I've got local versions of wax sealers for box sections and sills, but it's the general concept I'm after. I'm still not sure whether to use etch- or zinc-rich primer on the bare steel, THEN seam sealer, then to close in the section. Or to use a rust-coater like Dinitrol, then weld, then inject cavity wax in. I just don't like the idea of bare steel on the inside, that's all.

 

[Chickenjohn]

Good point!

best to spray the wax AFTER all welding and painting is complete.

 

[Grrrmachine]

For my situation, I think I will spray the inner faces with a zinc-rich primer, weld the area needed, and then pour in some warmed, thinned seam sealer, and then spray in some cavity wax. The affected area is a drain (between the bulkhead and scuttle of the car) so there are access points, but it's also an area that will get wet, so I really want to do the job properly.