15 replies to this topic

[minilady]

The underside of my mini is a mixture of the following surfaces:

- Completely bare new metal

- Lightly rusted metal

- Original painted surface

- Original paint with "underseal" and oil

My question is what's the best way of treating the new and lightly rusted metal so that it will resist rust, stone chips etc?

In the past I've found that Waxoyl generally gives the best protection if the metal is already partly rusted, but I don't think it works so well on clean metal or painted surfaces.

I have some Kurust (the sort which turns to a tough black layer which is paintable after a couple of hours), some "red oxide" primer (not sure if it really is red oxide though) and some Hammerite.

Hammerite is supposed to work directly onto both clean and rusted metal, but I plan to Kurust the lightly rusted stuff first, just to make sure. Then I'm not sure whether to coat the clean metal with red oxide first, or just Hammerite it? I'm reluctant to make the layers too thick otherwise they might crack with flexing of the floor.

Has anyone used Hammerite under the car? If so, did you apply to bare metal or use a primer?

Perplexed Paula

[Tom Sanderson]

the best thing to do would be to burn all the existing pint off so you have a clean working surface (time consumeing but worth it in the long run)
i would then put on some kure rust on the rusty places and spray with stone chip. and then waxoyl as well for extra protection
hope this is some help :tongue:

[pikey7]

I'm with Tom. I wouldn't bother with Hammerite as there are better things out there like the stonechip protection (by waxoyl, so actually contains some of the same stuff). Clean, cururs, primer and stonechip would (in fact will) be my way of doing it. Then use proper waxoyl in the sills and such like.

I'll be adding a topcoat of coloured halfords rattle can to it to get it the same colour as the rest of the car.

[minilady]

The repaired sills on my other car were coated with a grey stonechip protect product, over a variety of surfaces - bare metal, rusty metal and painted metal. I don't know the make, because it wasn't me who did it.

After a couple of years it began to crack microscopically, and let the water in. Although it looked perfect on the surface it was sopping wet and rusty underneath. The new plates had now rusted through from the *outside*. I feel they wouldn't have rusted that quickly if they'd been left bare!

So I don't trust stonechip protection as a defence against water. I feel it needs a proper waterproof paint layer underneath it.

In the areas where I'd slapped some hammerite on rusty metal, years before the stonechip was applied, the Hammerite was still adhering well and had protected the metal.

Conversely, in the areas repaired with "Trustan 123" rust killer, followed by a spray red oxide primer and a spray top coat, the rust had bubbled through.

So that's why I prefer Hammerite. But I've never tried putting it directly onto new metal without a primer. Well I have, but it didn't seem to stick as well as it does to rusty metal.

Any paint has the tendency to flake off, which is why I was wondering if it would be better to simply waxoyl over Kurust and forget paint altogether. I'm not going to show the car, so I don't care what it looks like underneath.

[A_SERIES_SUPPLIES]

My question is what's the best way of treating the new and lightly rusted metal so that it will resist rust, stone chips etc?

hi all
the best product for you to use in this situation is called

underbody shutz from bodyline available at any brown brothers outlet
it is available textured or smooth and you can paint on top of it.

most of the other under body protection you can get serious reactions when painting

you will need a compressor to apply this product and a shutz gun

i have used this for years with no problems at all and it looks good

thanks eddie

[1984mini25]

I have tried underseal and found all that does is allow mud and s**t to stick to the under side
Which don’t seam to be a good idea to me as mud has road salt mixed with it

As the underseal never totally dries

Now scraped it all off and brushed on 2 coats of red oxide primer,
2 some areas 3 coats of gloss black Hammerite then a light spray of stone chip especially in the really tight bits

Now hoping this will stop the mud build up and give an attractive look for longer

[minilady]

I thought Brown Brothers only sold to the trade?

Thanks for the advice, but I don't have a compressor (yet).

[pikey7]

Wurth do a lot of protectant paints too. Standard on Porsches, Mercs & Beemers, so I doubt if it's rubbish. I've used it on the Porsche before, and it's fine. Difficult to get hold of though. They also do an underbody "schutz" which is similar in it's finish to Hammertite, but a little more flexible, seems a bit more waxy, but is also overpaintable.

[THedooBZ]

on mine i first cleaned it off, then used frost metal ready.

http://www.frost.co....?productID=8229
then covered the underneath with hammerite to seal the metal, i put 3 thick coats on and it looks brilliant and will hopefully keep it rust free for a long time.
you can also spray waxoyl in any hard to reach places like in the rear valance etc...

[minimadjonesy]

^^^^i used this stuff too! bloody excellent stuff! used it on my current mini!

[Lomcevac]

Where stonechip is really useful is that you can spray it over almost anything (including underseal or wax) and then paint on top of it.

I was in a similar position to you and this is what I did:

1 Treat any bare metal/removed rust with rust products.
2 Prime above areas with etch primer.
3 Spray whole underside with a modern 'self healing' type of undrseal containing Waxoyl.
4 Spray stonechip over underseal when dry to provide a base for paint.
5 Spray body colour over stonechip.

The waxoyl needs to have dried properly before going over it with the stonechip. I'm hoping that the above will give good protection and lok good too.

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[Paintman]

Where stonechip is really useful is that you can spray it over almost anything (including underseal or wax) and then paint on top of it.

Stone guarding over underseal or waxoyl will not the way to do things at all.
You need a good key for the stoneguard to grab hold of; waxoyl and underseal are NOT a sound base for stoneguard.

All you need to apply is POR 15 or similar plus etch primer to any bare metalled areas then followed a primer and then either underseal or stoneguard. After stone guarding you can then apply the colour. Never spray over underseal, its tar based and it will discolour the paint also in time the paint will flake off.

[Lomcevac]

Paintman

You are of course right and the way I have described is not the correct way to do it. I have to say that the paint underthe Spitfire that I restored is still looking good after more than 10 years, having used the method above, but I have probably been lucky in my choice of products/environment etc.

Regards

[dean_chad]

ive used a zink primer and stonechip on my project. hides imperfection, acts as a sound deadener and looks great, like an orange peel affect

[Amy]

All you need to apply is POR 15 or similar plus etch primer to any bare metalled areas then followed a primer and then either underseal or stoneguard.

We're using POR 15 on my woody estate project where ever we can... It's brilliant stuff, Sy used a couple of coats of it straight over rusty metal on his Pick-up spaceframe, just to protect it this winter (before the rebuild starts)....
It looks like new and there isn't even a spot of rust showing!!! Even though the whole lot will be stripped off again for proper rust removal etc. There would probably be no need.....

Definitely seems to be better stuff than Hammerite, although it is thinner, so can be prone to runs....

Good Luck!