Getting A Good Finish On Cast Aluminium

Marc-M

Marc-M

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Over the years I have tried to get a good finish with aluminium and failed.
So, the last time I needed my bits doing, I had them vapour blasted- they came out great, and the cost for the few bits was dammed $$$$$$$….


So, with a little help from the web and a few tips from youtube I tried a slightly different way and i hope it may help a few folk in the quest for a good finish...
I have a cheap blast cabinet that has never performed very well, but I decided to do the modifications that a few YouTube blogs have done.
The main thing was to make a metering valve – these are not cheap and cost as much as the cabinet – so I again found a youtuber who made one out of plumbing bits (commercial cast iron ones) so I made one that cost £18.00…
This makes a huge difference….



The trick is to blast the aluminium with normal hard sharp media at say 80 psi to get it clean.
This should give you a nice and clean finish but the surface is quite course matt and open (marks quite easy)

Then change the media for glass beads ( I used 100-200microns medium) – use new glass beads as they make the aluminium have a better satin shine BUT lower the pressure to 40 to 50 psi – this 2nd process only takes a few minutes and you can see it shine up in the cabinet as you work - even did the sump!!
I would say the 2nd process with the glass beads is not cleaning but peening …

Anyhow here are my results – I’m very happy with them and because the surface is closed – they are easy to keep clean and I think looks as good if not better than new – and it costs very little.




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My Engine bay ... not so good
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Very nice, after I blasted mine I just polish mine occasionally with Colonite Metal Wax and it stays clean.
 
Looks great! As far as the clear coat, powder coat, ceramic coat goes, if you're going to go that route do you need to use the glass bead? Seems like a "course" surface would work fine with a coating.

IE: When I refurbish headlights I sand the old clear coat off and continue sanding down to 800 or 1000 grit, which leaves a frosty or dull look to the lens. I clear coat right over that without anymore sanding or polishing and it turns crystal clear. I'd assume aluminum would do the same thing after blasting and coating.
 
Marc
Can you tell us more about the modifications to the cabinet and what you did to make the metering valve etc? Perhaps the links to the YouTube approach that you took.
The results look great, I am impressed.
 
Cornishman said:
Marc
Can you tell us more about the modifications to the cabinet and what you did to make the metering valve etc? Perhaps the links to the YouTube approach that you took.
The results look great, I am impressed.
Click to expand...
Good point. Based on your post ”all” your are doing is 1) blast with regular media at 80 to get it clean and 2) switch to glass beads at 40 for a smooth finish. It sounds like something any normal cabinet could do.
Where do the modifications come in? Is it mainly that the pressure metering on a standard compressor is not precise enough?
The results look awesome though!
 
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dang said:
When I refurbish headlights I sand the old clear coat off and continue sanding down to 800 or 1000 grit, which leaves a frosty or dull look to the lens. I clear coat right over that without anymore sanding or polishing and it turns crystal clear.
Click to expand...

What clear coat are you removing off a headlight? Clear-coated lenses??
 
Luis A. said:
What clear coat are you removing off a headlight? Clear-coated lenses??
Click to expand...
Every oem plastic headlight that I've restored had a clear coat on it from the factory, or it acts like a clear coat if it's not. When the lights start fading and you can see a distinct difference between areas of the light it's usually the clear coat coming off. No other way to fix it other than removing the outer layer and re-coating it.
 
I second the use the clear ceramic coating, paint or powder coat looks, well, painted
The ceramic looks very close to un-coated aluminum
That is what they do at Speedway
I think the best brand is Cerakot, you might find someone that does it locally to you
But not all shops, even certified by Cerakot don't do a good job
And you cannot get it off without sanding or blasting, it is very tough
 
“Every oem plastic headlight...”
What is the best clear coating for rrpolished headlamps?
 
The other thing you can do, rather than vapor blasting, especially if you just have a few parts
WD40 and a brass 'wheel' brush on a drill
BUT, you have to use a real brass brush, the ones you see at the hardware store are brass plated steel and will ruin aluminum parts
A real one will be about $50 and you will have to 'mail order' it
 
Not actual experience but this topic interest me so I'll chuck in something I heard first hand from Bruce Canepa (Canepa motorsport).

A very low mile, original 1996—97 Porsche 993 GT2 RS Evo (extremely rare) was on the lift and there were several people commenting on the stunning suspension components and amazing condition of the aluminum finish. The concensus was everything had been replated. Bruce stepped up and went into an explanation of how they had just purchased a very high end Vapor blaster and how utterly amazing it was. The components had been removed, blasted and put back on the car. No additional steps. He compared this to their previous 7 (seven!) step process they had developed over the years, that took much, much more labor and time to get right. He was blown away by how much time it saved.... Here are a couple pics...

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