Protecting the rear of a new car wing

[thepurpleblob]

I am replacing a couple of wings on by BMW 3 series due to rusty arches. I've got the outside painted the body colour but the rear is just black primer.

I'd be interested in thoughts/recommendations about what to use to properly protect the rear. This is my daily "smoker" and is subject to everything a Scottish winter can throw at it!

 

[gt6s]

I am presuming you are referring to the inside of the panel.

Waxoil.

Laurence

 

[thepurpleblob]

Yes - the inside of the panel.

Just Waxoil? No painting or underseal?

 

[steveo3002]

how mad do you want to go?

ideal world , key the panel epoxy prime /top coat /cavity wax

id at least try to get a keyyed coat of paint around it before cavity wax

 

[thepurpleblob]

That's what I was thinking... any product recommendations?

Pattern wings aren't the best but I don't want to be doing it all again next year. It's an old car but it goes and gets me to the station every morning

 

[steveo3002]

jotun jotamastic if youre feeling spendy

aldi metal paint if not

 

[slim_boy_fat]

That's what I was thinking... any product recommendations?

POR-15? [stands by to be torn to shreds and/or ] Or if you can find out what's used on the offshore rigs, that would be a good alternative.

Maybe some like @Rig Pig or @Burdekin might be able to advise?

Are the wings genuine BMW? I've read that some pattern panels can be a good fit, but others can need a lot of fettling in order to get an acceptable result with . Let's see some pics when you're doing the job.

 

[johnik]

POR-15? [stands by to be torn to shreds and/or ] Or if you can find out what's used on the offshore rigs, that would be a good alternative.

i bought a Locost 7 chassis that had been painted with por 15, it was rough as a badgers rear end so i decided to remove or at least flatten it down a bit, i gave up after realising that nothing short of a thermo nuclear device was going to scratch the surface of the stuff, no wonder they use it on oil rigs and the like.

 

[thepurpleblob]

Most pattern wings I have bought in recent years have been a pretty good fit. I don't think the metal is as good as the originals. Or it's hard to replicate the protection given in the factory paint shops.

 

[thepurpleblob]

I ordered some POR-15! I've got some chassis parts to make pretty too so it should be ideal. I keep hearing about the stuff so I'd better give it a go!

 

[ajlelectronics]

I ordered some POR-15! I've got some chassis parts to make pretty too so it should be ideal. I keep hearing about the stuff so I'd better give it a go!

NOT suitable for fresh steel. Rough, pitted old metal it is ideal for, but no amount of prep will stop it coming off in sheets, on new metal.

You should be looking to epoxy prime. If not on show, you don't need to top coat it and it is perfect for old or new metal.

 

[Burdekin]

I ordered some POR-15! I've got some chassis parts to make pretty too so it should be ideal. I keep hearing about the stuff so I'd better give it a go!

It will delaminate after a wee while, I know this from experience. A 2k epoxy mastic like Jotamastic 87 is a better quality alternative and much cheaper...

 

[bricol]

From experience I wouldn't be to optimistic of any epoxy paint staying on a smooth, un-blasted metal surface for as long as you want it.

Several layers of paint, followed by a good coating of the under-body mastic/stone chip of your choice.

Cavity wax on a panel blasted by all the crap thrown up by road wheels isn't worth it. In the joints maybe.

 

[steveo3002]

NOT suitable for fresh steel. Rough, pitted old metal it is ideal for, but no amount of prep will stop it coming off in sheets, on new metal.

You should be looking to epoxy prime. If not on show, you don't need to top coat it and it is perfect for old or new metal.

por15 is a terrible choice unless youre sandblasting it , comes off in sheets unless its on rough steel

could have got epoxy for the same money

 

[ajlelectronics]

From experience I wouldn't be to optimistic of any epoxy paint staying on a smooth, un-blasted metal surface for as long as you want it.

Then your technique is at fault. Epoxy primer is a better performer than etch primers or anything else. Part of the required prep is to key to 120 grit and clean. It works on almost any substrate including aluminium and is inert to following coats. Waterproof, robust and easy to apply without air fed equipment. I have yet to have a failure either on metal or fibreglass. POR-15 on the other hand has been perfectly good on rough substrates which is is meant for and appalling on smooth new metal.

 

[Rig Pig]

I will ask the painters what they use when I get back, but surface prep seems to be the most important thing. The bits they blast clean last, the bits that get needle gunned don't seem to be anywhere near as good.

 

[MG David]

You need to find out if the primer on the inside of the wing is good quality or just transit primer. Take a rag with thinner on and give it a wipe. If it comes off strip it roughen the surface with 120 as per aj above, clean and then epoxy primer. After that you can carry on with stone chip top coat or what ever.

 

[bricol]

Then your technique is at fault. Epoxy primer is a better performer than etch primers or anything else. Part of the required prep is to key to 120 grit and clean. It works on almost any substrate including aluminium and is inert to following coats. Waterproof, robust and easy to apply without air fed equipment. I have yet to have a failure either on metal or fibreglass. POR-15 on the other hand has been perfectly good on rough substrates which is is meant for and appalling on smooth new metal.

'Fraid not - as I said, on smooth, unblasted steel, it won't still be sticking there in ten years time, from real life experience. As you then go on to say - it needs keying. Wire brushed, or bare steel, it doesn't seem to stick, certainly not as long as properly blasted steel - that's after ten years of pretty much daily use in all weathers.

If I was painting un-blasted steel, I'd be sticking to conventional paints - it doesn't seem to detach in flakes/sheets allowing unseen moisture underneath.

blasted steel to the spec called for in the application instructions, I'm massively impressed with it's longevity.

 

[steveo3002]

same with anything isnt it? not much out there to paint onto polished steel and if there is it will still benefit from a good key

 

[postie jon]

scotchbrite with a red scocthbrite pad, clean de-wax , good coat of self etch primer, can of 3m underbody or wurth stonechip, leave to harden off ,then if u want a coat of colour or wax to seal , thats all we did to genuine panels and never had any problems , its probably treated with black cathodic primer to prevent corosion which you are not recomended to remove.