paintwork/underseal question

[pedGSR]

this is what happens when you don't prepare the surface properly before applying waxoil.



its rusted from behind. I only applied it a year ago so has corroded quickly.

so what is the best next step? I have a tin of por15 in the shed so should I give it a coat of that before resealing?

also what could I use to remove all the old waxoil? a wirebrush is all I have used so far but there is a shit load of residue left.

[russ979]

Bloody rust!
I would rub all that down Pete, Maybe use some thinners. The force of habit i have is when ever i have bare metal i use a brush on rust treatment even if its clean bare metal. Then if you are using waxoil give it a good coat of primer first.
I like using Shultz as that can be easily painted over and is more of an oem finish.

[Stuart]

Sorry to state the obvious but painting is only as good as the preparation. To ensure a car is totally rust free before undersealing is not practical for most people. It would require completely stripping, chemical dipping or spraying with an abrasive media prior to painting with (usually) a zinc based primer before painting with cellulose/water based goodness. As very few people can do that, even professional people who provide an undersealing service ( ) have to make the best of the situation. With access to ramps, technical knowledge and all the tools there is no way that I can guarantee that all rust ON INTERNAL joints, seams and areas has been removed prior to my work. I can correctly prepare the surfaces I can get to but even then, many clients don't want to spend the money on two to three days of labour to get the floor pan and arches 100% prior to undersealing.

Trying to do a decent job of undersealing without ramps, airlines, good lighting etc would be a mission I wouldn't take on and I've undersealed more cars than most. Por15 is excellent and 3M schutz is good for arches. Make sure you get plenty of protection on the arch returns as they are super prone to rusting through.

Good luck

[Stuart]

To remove the old waxoyl you can use anything petroleum based. I use a product called Tardis but old fuel would do the trick or brake cleaner.

[pedGSR]

Thanks guys. The usual has happened where the more old material I remove, the deeper the rust seems to be. It's going to be a case of lots of prepping, jenolite the 'pits' left by the rust and then te por15. Lots of effort but needs doing as best as possible before it gets worse.

Pete.