Painting underneath

Post by **youngun** » Sun Jul 13, 2008 4:51 pm

With a bit of luck ill be stripping and painting the underside of the car in the next few weeks. The plan is to use chassis black and tetroshutz (or however you spell it!), but i was wondering what the best paint is to apply to the bare metal? Do i reach deep into my pockets and get the POR-15 rust preventative paint or just slap on a lot of zinc rich primer?

thanks,
YG

Post by **MoggyTech** » Sun Jul 13, 2008 6:53 pm

You want a primer that will give maximum grip for the chassis black to prevent flaking. The two I have used and both give eaxcellent results, are Bilt Hambler, or #1 Rust Beater Primer by Finnigans.

Post by **youngun** » Sun Jul 13, 2008 9:37 pm

Hmmm, ive heard of neither! thanks moggytech, ill google them both!

Post by **les** » Sun Jul 13, 2008 10:18 pm

I've often wondered on this question, but what has paid off for me is ---zinc primer (bonda) followed by hammerite smooth ( I know some folk hate it) then cover (not too thick )with waxoyl underseal and a few weeks later sprayed with normal waxoyl, which can be repeated every few years. Ten years on all ok.

Post by **Sidney'61** » Sun Jul 13, 2008 10:43 pm

Yup i just used hammerite on mine, the only hammerite I had in the garage which turned out to be white! Made out for a pretty underside!

Post by **chickenjohn** » Mon Jul 14, 2008 7:13 am

for me- Zinc primer (90% zinc =heavy tins), seam seal any welds, chassis black, then underbody wax (waxoyl/Dinitrol). For high impact areas, use overpaintable stonechip coating before the chassis black coat.

"tetraschultz" I think is underseal, personally, I wouldnt use that.

Post by **youngun** » Mon Jul 14, 2008 7:34 pm

Hmm, well i rekkon its going to be a shed load of seam seal, zinc primer, stonechip, chassis black and waxoyl then.
Thanks people!

Post by **les** » Mon Jul 14, 2008 9:36 pm

If you go the seam sealer route cleaning first with thinners is a good plan. Mind you it's a good idea to have continuous welds underneath, in which case seam seal is redundant.

Post by **bigginger** » Mon Jul 14, 2008 9:51 pm

Not if your welding's like mine, it isn't

Post by **chickenjohn** » Tue Jul 15, 2008 9:10 am

les wrote:If you go the seam sealer route cleaning first with thinners is a good plan. Mind you it's a good idea to have continuous welds underneath, in which case seam seal is redundant.

Agree that continuous welds are the best- certainly for MOT purposes. However, even a visually completely continuous appearing weld can have a few tiny pinholes or tiny gaps, corners etc where moisture can get in and start rusting so I like to dress the weld down to get it even with the grinder, then wire brush on drill to clean it up, as you suggest, clean with thinners (or panel wipe) then zinc prime, then seam seal. Chassis black, then waxoyl.

My view is its belt and braces, after doing all that work on the cutting and welding side, I want the repair work to last.

Post by **les** » Tue Jul 15, 2008 10:36 pm

I like to dress the weld down to get it even with the grinder

I share your obsession or should I say care!