David Jenkins
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| posted on 11/3/04 at 10:55 AM |
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Painting anodised aluminium
Here's a question for the painting experts...
I know that plain aluminium doesn't take paint well without an etch primer, but what happens when the ali is anodised? Does this hard and
stable coating that's very firmly attached make painting any easier? Or does it make it more prone to chipping?
I'm planning to spray-paint my radiator grille mesh, but I don't want it to chip off every time I go out on the road!
cheers,
David
[Edited on 11/3/04 by David Jenkins]
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Spyderman
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| posted on 11/3/04 at 11:34 AM |
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It will still need etch priming if you want it to stay on.
Why not anodise it yourself to the colour you want?
Anodising is not a coating it is a dye used on the surface.
Spyderman
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Mix
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| posted on 11/3/04 at 11:56 AM |
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Anodising is an electrochemical process, see http://www.lbparkes.co.uk/techinfo.html
The resultant surface will then accept a dyed finish. Rather than paint the grill why not just re dye it ??
Mick
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David Jenkins
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| posted on 11/3/04 at 12:11 PM |
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quote:
Originally posted by Spyderman
Anodising is not a coating it is a dye used on the surface.
Anodising is a way of applying a film of aluminium oxide (as found in abrasive paper) that is formed electrically on the surface. A
'film' is pretty much the same as a 'coating' to me - whatever the name, it's a thin layer on top of the metal! This
coating will accept a dye when newly created. Once it's dyed then the piece is put in boiling water to fix the dye and seal the anodising.
I don't think that it can be re-dyed afterwards. Even if you could re-dye, I believe that black is the hardest colour to get right, hence my
plan to paint it.
rgds,
David
[Edited on 11/3/04 by David Jenkins]
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DavidM
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| posted on 11/3/04 at 11:58 PM |
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Pure aluminium is corrosion resistant due to being naturally endowed with a tenacious oxide film on the surface. Alloys of aluminium are less
corrosion resistant as the alloying substances degrade the ability of the aluminium to form said oxide film. Anodising is an artificial thickening of
the oxide film which restores the corrosion resistance of Aluminium alloys to somewhere near that of pure aluminium. All coloured anodising may
exhibit slight variations between different components, but will generally be stable across a single component.
Aluminium is the most common metal on earth, forming 7.62% of the earths crust, but is comparitively expensive because of the large amounts of energy
needed to extract it from the Bauxite ore.
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thekafer
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| posted on 12/3/04 at 01:00 AM |
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[I don't think that it can be re-dyed afterwards. Even if you could re-dye, I believe that black is the hardest colour to get right, hence my
plan to paint it.
David
[Edited on 11/3/04 by David Jenkins]
Anodizing comes off the same way it goes on,you simply reverse the current and it removes the plating. A radiator grill would be a good candidate for
sulfuric hard anodizing. It would be bullet proof and would resist stone chipping. Ask the plater
for "MIL-A-8625,TYPEII,CLASS 2"BLACK.
Oh,it cost about the same as regular sulfuric anodizing 
good luck,Fletch.
I'd rather have a bottle in front of me than a frontal labotomy...
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David Jenkins
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| posted on 12/3/04 at 07:08 AM |
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Fletch,
There are a few problems (as always  )
I live in a rural area not noted for its industrial background - the only anodisers I could find for another bit of the car wouldn't even
consider doing a couple of small bits of uncoloured anodising (plain silver colour). They were only interested in big orders.
Also, trying to convince these people that I wanted a MIL spec colour would be 'entertaining'.
rgds,
David
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Spyderman
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| posted on 12/3/04 at 01:09 PM |
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I thought this sight was about low cost DIY car building?
It seems that the more you try to help some the more you get critisized!
See other threads about anodising to see how easy it is for DIY.
If you just can't be bothered with the options offered then just say so. Don't pick faults in their suggestions if you have no intention
of using them.
Spyderman
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David Jenkins
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| posted on 12/3/04 at 01:59 PM |
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Get out of the wrong side of the bed, did we?
I wasn't criticising anyone - and remember that you originally told me very bluntly that I was wrong!
I have received a whole range of very useful suggestions both in this thread and in others over the last few days - some I will adopt, and others I
will store for possible later use.
Just don't be so touchy...
David
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Dave Ashurst
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| posted on 12/3/04 at 07:19 PM |
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snigger snigger..
I just love competitive aluminium metallurgy  
Shame it had to end. I'm booking my seat for the next round! When is it by the way?
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David Jenkins
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| posted on 12/3/04 at 08:12 PM |
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I'll think of something...
DJ
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thekafer
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| posted on 12/3/04 at 11:05 PM |
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quote:
Originally posted by David Jenkins
Fletch,
There are a few problems (as always )
I live in a rural area not noted for its industrial background - the only anodisers I could find for another bit of the car wouldn't even
consider doing a couple of small bits of uncoloured anodising (plain silver colour). They were only interested in big orders.
Also, trying to convince these people that I wanted a MIL spec colour would be 'entertaining'.
O.k. , Does anyone near you do powder coating? Much easier process (more likely to find a"mom&pop"place) Still very durable.
I'd rather have a bottle in front of me than a frontal labotomy...
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David Jenkins
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| posted on 13/3/04 at 10:21 PM |
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quote:
Originally posted by thekafer
O.k. , Does anyone near you do powder coating? Much easier process (more likely to find a"mom&pop"place) Still very durable.
That's "plan B" at the moment - I do know of a local place that will cheerfully take small jobs - but it means taking a day off work
as they don't open on Saturdays.
cheers,
David
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Hellfire
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| posted on 13/3/04 at 10:41 PM |
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That Dave Ashurst
what a dog!
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Spyderman
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| posted on 14/3/04 at 12:15 AM |
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quote:
Originally posted by Spyderman
It will still need etch priming if you want it to stay on.
Why not anodise it yourself to the colour you want?
Anodising is not a coating it is a dye used on the surface.
David Jenkins:
Where does it say above that you were wrong?
This was the original question!
quote:
Originally posted by David Jenkins
I know that plain aluminium doesn't take paint well without an etch primer, but what happens when the ali is anodised? Does this hard and stable
coating that's very firmly attached make painting any easier? Or does it make it more prone to chipping?
Whatever you choose to call it does not make anodising a coating! I was merely pointing out the difference.
I don't make assumptions about your knowledge, so please don't make them about mine!
If I say something it is for good reason, not just to sound clever or to try to make someone else look small.
You can take my help in the way it is intended or you can ignore it!
Either way is fine, but don't critisize help that is offered.
And I think I'm perfectly entitled to be touchy the way you reply!
[Edited on 14/3/04 by Spyderman]
Spyderman
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David Jenkins
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| posted on 14/3/04 at 07:25 PM |
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Who me?
I'm a nice friendly chap really...
but apart from anything else, I can't be bothered to argue... there's more important things to worry about in life... and if I sounded
rude or stroppy then it wasn't intended.
As I said earlier though, I do take note of what people say, but reserve the right to make up my own mind about what I do in the end. Sometimes I ask
a question, get a load of good answers and go and do something else anyway - but it's usually the answers I got that made me think about what I
was trying to achieve, and made the solution clear.
Anyway, "Peace and Love, Man!" (well, the hippy isn't around, so someone's got to say the words!)
David
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