15 replies to this topic

[Yams]

So after some digging around on the forums I can’t find anything on this topic (I’m not so great at using the search function, maybe I was being too specific?)

Anyway I’m referbing some doors, they were re-skinned by the mini door company. Some of the welds have cracked away where the skin meets the frame (Heard this is common?) so I’ll grind that and re-weld it. My question is though, what primer? I’m spraying the doors up to be re-sprayed when the whole car goes in for it. But I don’t know what primer is best suited to this. I’ll be using rattle cans for the time being on the doors, because I’ll only have to do it in small patches since I believe the skins are magnetically primed or something.

 

So, High-build? Etch? Red oxide? Standard grey? Weld Primer?

 

It seems confusing to me because some are saying high build, others etch, and other people are saying just put anything on it to slow oxidisation.

 

Help!

 

Yams

 

 

[Midas Mk1]

I'd advise to strip the poor quality e coat off and acid etch them, make sure the insides of the skins are painted / prepped too.
Looks like mine wernt, and it's causing me issues now....

[AVV IT]

Etch is generally an acid based primer that "etches" itself into the surface of the metal. So if you have exposed/ bare metal, then it's worth starting with a coat of etch primer (etch primer also tends to be weld through as well). After that, I tend to use a decent quality zinc based primer for added protection (some prefer modern epoxy based primers as opposed to zinc based products and others will argue that zinc based primer works best when applied direct to bare metal though).

I tend to then spray top coat directly over zinc primer, but you can put on a few coats of standard primer if you wish. I don't tend to bother with red oxide any more, it was a good product in its day, but there are much better modern base primers out there these days.

Edited by AVV IT, 17 June 2013 - 03:19 PM.

[Yams]

Thats some great advice guys, thanks for your time. Should i etc prime the inside or the skins? It has a black coat on them already and i was just going to wax them inside, would a good priming and topcoat be advised for the insides too?

Also from what i gather etch and zinc are for 'metal' priming, does that mean that high-build primer is more for a coat to get an even surface when sanding back and smoothing?

[sonikk4]

The black coat inside the door will be the coating the skins normally come in unless the they were sprayed black before fitting. Worth asking them the question.

If it was the coating the skin came with then it needs to be cleaned off then etch primed primed and painted. Do not be tempted to leave it as its not waterproof.

Also it flakes off so not suitable to over paint.

 

Speaking from experience here i never ever leave the coating on unless its a Heritage skin then their E coat is far superior.

[Yams]

OK thanks a lot, it think its just the standard coating. Is there any tips to getting the coating off from inside the skin? Its way to tight to get a sander in there let alone my hand

[black olive]

heres what Im doing. filler on any imperfections, acid etch for bare metal, few coats of high build then wet flat and topcoat

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[sonikk4]

If they are Magnum skins or equivalent then you will be able to use standard thinners to remove it. That's all i use now rather than sanding or using a knotted wheel.

 

It stinks so use a mask but it works perfectly. 

[HarrysMini]

I'm using Red Oxide on my panels as my final colour will be red. It's not waterproof though, so it's a good idea to topcoat it as soon as it's fitted. 

In my experience Red Oxide is the most protective as it is rust inhibiting.

[sonikk4]

Unless you have red oxide from a boat yard then the spray stuff from Halfords or a paint shop is red primer.

[Yams]

Unless you have red oxide from a boat yard then the spray stuff from Halfords or a paint shop is red primer.

 

Yup, i work at halfords. The rattle cans labled as 'red primer' are exactly what it says on the tin. Only red oxide there is in a tin that you have to mix with thinners and spray from a gun.

[HarrysMini]

What I am talking about is actual Red Oxide. Hammerite make it. Red primer is a different product.

[crazypainter]

you should use etch primer on bare metal and either 2k primer surafcer, or 2k high build depending on weather you are going over filler repairs, high build for filler repairs. no tinnie can primer is much good, especially the high build as its piss thin and wont give you your build on the primer you will need.

 

if you are havinng the car painted, why not just do some filler work and generally protect the bare metal and leave the rest up to the painters? trust me we had self prepped stuff

[tiger99]

Zinc primer on top of etch is pointless, as it needs to be in intimate contact with bare steel to add corrosion protection. It is also fairly weak, and may peel off. Zinc on top of grit blasted metal to give it a good key is ok, but a good epoxy primer such as Lechler on top of the etch will give better overall protection, usually.

 

As for red oxide, well read lead, now highly illegal, may have worked, but the stuff commonly sold now does not. It is just a very ordinary primer with very ordinary adhesion, and a red colour, to capitalise on what people think, based on past history, is going to work. Basically, a complete fraud, like a lot of alleged rust remedies.

 

Weld-through primer is usually zinc based, and that is ok in a seam, where it is mechanically protected. Use it on seams before they are welded, and etch everywhere else. Best to mask the seams with a strip of tape, apply the etch, and then peel of fthe tape and apply the zinc, because if you do it the other way around, the etch primer will remove the edges of the zinc.

Edited by tiger99, 19 June 2013 - 12:10 PM.

[jaydee]

The stuff they sell as red oxide is just a different red primer and is the worst stuff at rust protection, it does nothing.

Beware spryaing any kind of paint over hammerite stuff, it may react..

And remember if you dont sand down the black coating paint from new panels, whatever they're genuine or not, paint will never stick to the surface, this applies to all kind of panel works

Edited by jaydee, 19 June 2013 - 02:06 PM.