Spraying Metallic - Help....!

[Steve Walker]

Hi -

Needed to replace my roof-mounted carphone aerial recently, after it lost a fight with a low-hanging branch. Decided to mount the replacement further back on clean undisturbed steel, and do a filler repair on the distorted hole left by the old one. I managed a lovely smooth repair with mesh-reinforced Plastic Padding, sanded off with 1200 wet & dry. Went out and bought a specially-mixed exact-match aerosol of dark blue paint, but now I just can't get any kind of half-decent paint finish over it.

I masked off the area (approx playing card sized), and applied about 6-8 light sprays (with 10min intervals to allow it to go tacky). Left this for a week to harden off, and you could easily see boundaries where one spray run had overlapped another etc. Got the metallic T-Cut out to blend it yesterday, only to find that this removed the colour layer! I was just left with a really weird silvery / undercoaty patch.

Tried to spray again today, but I can't apply it softly enough to avoid obvious layers. I assume that this will mean polishing again, which will remove the colour again. The area needing respray is now an inch wider on all sides, and it's going to grow each time I get it wrong.

A quick scamper around google suggests that it's practically impossible to spray a small section of car body, especially with a standard aerosol can, and the whole panel usually has to be redone. Can't believe this - surely there's some way to get a *reasonable* finish? I don't want concours, just a smooth, more or less matching result.

I'm now torn between buying a little airbrush kit to see if an accurate, gentle & slow application works any better, or else calling in one of those cosmetic repair firms from the yellow pages.

Any advice would be gratefully appreciated!

Thanks - Steve

[Martin]

You need to check this, but I've only come across 2-pack metallic finishes: the metallic paint and a clear laquer finish. I don't know if modern finishes are similarly 2-pack or if there is any laquer in the aerosol you were given, but from the sound of it, you haven't been told to finish off with a spray coat from a can of clear laquer. You should be able to get the laquer from the same supplier as the base coat to ensure compatibility. Then, by all means, use T-Cut to blend/polish the laquer.

Does this make sense?

Martin

[Steve Walker]

Yeah, it does - thanks for this Martin.

I've seen the clear lacquer coat referred to, but assumed I didn't need it. The aerosol gives a lovely finish without it - I checked a piece of the oversprayed masking paper against the car body and the match was perfect. But now I'm wondering if the lacquer would help - gotta be worth a try for a fiver.

[Doki]

You need to bear in mind that aerosol paint is very thin compared to paint you'd actually put through a spraygun due to the propellant and the lack of pressure pushing it out. I'd be very tempted to put a heavy coat on - it's a roof, it shouldn't run unless you go really mad. And all metallic finishes I've seen in aerosols need a lacquer coat. This is good, because it helps you hide the repair. Cover more than the sprayed area with lacquer, then polish it up. Be very wary of polishing aerosol paint for a good while (a warm week later say). I'd also avoid trying to mask the immediate area - mask most of the rest of the roof, but leave a good area around where you're spraying unmasked, to avoid masking lines, then polish out any overspray.

Aerosol paint is definately not 2 pack btw - 2 pack is paint that's mixed with a hardener to make it set.

[Steve Walker]

Thanks Doki, that almost inspires me to have one more go.... :o)

[Doki]

And you need to bear in mind that metallic finishes vary by thickness of coat - thin, and all the metallic bits line up flat. Thicker and they end up all angles...

[MrCheerful]

very fine rubbing compound over the whole panel, very fine rub down over the area, overlap the area with paint (no masking) do not flat , then lacquer over a larger area.

Your chances of a good match are very low.

Mrcheerful

[The Natural Philosopher]

Its doable with plain color, but you will never get a match with metallics.

Prep it up and take it to a pro spray place and get the whole panel done.

It wont cost that much..its the prepping up they charge for.

[meow2222]

metallic paint must have a clear lacquer topcoat, otherwise it a) doesnt look gloss b) is weak and scratches readily c) the ali flakes oxidise, making it look an eyesore after a while.

But basically youve found out the hard way that patching metallic will never work well. Either go with a straight hard edge, dont sand it, and accept it, or respray the whole panel for a quality result. Theres no way youre going to feather the stuff successfully.

NT

[adder1969]

Sometimes a thick or wet enough layer will dry smooth and glossy and if you mask the area with the edges of the tape lifted up you can sometimes confine the spray to the area without a hard edge line.

Alternatively put a contrasting stripe down the length of the roof or a contrasting round dot so it looks like it's supposed to be there.

[Chris Bartram]

A similar trick is to fold the tape back on itself to avoid the edge.