coating internal panels before welding etc

[Ride_on]

I am rebuilding my sills and am starting to put on major bits that will be mostly internal. What are you supposed to coat these with to get good rust protection?

I am thinking of a weld through primer or cold zinc coating as this seems a good protection, except that they seem incompatible with cellulose primers and talk about a water based barrier coating. Anyone know what this is?

For the outside, I expect to build up to primer coat and leave painting to the professionals, I generally use Davids Zinc 182 primer. I'll then do an internal wax rust proofing.

[Chris_C]

All the internals of mine I covered in 182, but I've gone off it of late based on leaving it also externally to see how well it stood up to the winter. I know primers arn't waterproof but was just intrigued to see what the internal of my sill was going to stand up like

Hammerite No1 Rust primer seems to stand up pretty awesomely to the weather, but I've not tried welding through it yet.

[SteveP]

leaving it also externally to see how well it stood up to the winter. I know primers arn't waterproof but was just intrigued to see what the internal of my sill was going to stand up like

Ohhh so that's why it's still not painted, not down to the fact you're being lazy?

[Chris_C]

Yup, it was always planned as a scientific experiment

The 182 did get really quite bad there was a fair amount of surface rust blooming through the primer, but the stuff done in No1 hasn't even tried to start rusting. I think that says a lot tbh! I'll topcoat straight over the No.1 when I purchase a fair quantity of the stuff, I'm fed up of the tiny volvo spray cans.

[Ride_on]

I did alot of rust repair on my 1980 340 20 years ago (it was already rusting badly in 1985), the 182 was the best primer at the time, but is no replacement for the zinc electroplating and can't be welded through. I found a product called zinc plate which was quite good and didn't complain about cellulose and certainly worked but the aerosols tended to block, I haven't found it since. 182 is certainly not weatherproof and IMO not suitable for internals on its own, and therefore no use. Since then I have been impressed by the claims of rust bullet, a moisture curing paint that sucks the water out of existing rust and should give protection for 10 years, which is similar to Zinc e-plate, but you can't weld through it so not good for lap joint seams. The cold zinc coating also looks impressive but most products say it cannot be over coated directly with cellulose based products, its designed to be left alone or overcoated directly with 2K.

I've also tried electroplating but haven't been very successful with stuff on the car, ie only dipping works.