Aluminium......best way to finish?

castaway

castaway

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I am just finishing building myself an aluminium bracket to support my wind generater off the front of my mizzen mast.

Ideally I would anodise it but having spoken to a company dealing with this, they implied that I would be paying 'well in excess of their minimum charge of 85 quid!!' I think maybe I might go with paint instead...

Anyone got experience with etch primers and so forth?

Thanks Nick
 
Hammerite do a "Special Metals Primer" which is suitable for Aluminium. I used it on a Alu bow roller and then painted it with silver Hammerite and it worked just fine.
 
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Hammerite do a "Special Metals Primer" which is suitable for Aluminium. I used it on a Alu bow roller and then painted it with silver Hammerite and it worked just fine.

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It would be very helpful if you could enlarge on the last four words.
How long has it been in service? How much 'wear and tear' has it taken: does your anchor just sit there, or has the chain been over it a hundred times; etc?
This is not to be critical of your contribution: I have to treat a repaired aluminium mast-step very soon, and good information would be much appreciated!
 
Anodizing will be the only totally acceptable treatment.

If you must paint then start with an etch primer. Look at International's website for full details.

Also try other paint manufacturers eg Blakes

Hammerite primer for aluminium follwed by Hammerite or Smoothrite is the cheap option. So long as it is not bashed about it may be OK
 
Try giving John Meelan a ring at OTI in N. Wales. They do anodising, and their minimum charge was nothing like £85. (more like £25).

Their number is 01824 704991. I do some work for them occasionally, but would recommend them anyway.

You would need to post the bits to them.

(Yay! Wales just scored /forums/images/graemlins/smile.gif /forums/images/graemlins/smile.gif )

Andy
 
If you google anodising there are some very usefull diy sites explaining how to in natural and colours.
Did some a few years ago and it was easy, basic and interesting, very heath robinson "O" Level chemistry and physics
Good luck dont forget eye and skin protection.
Keith
 
If you have fabricated the bracket from 'proper' marine grade aluminium, you could just leave it as it - with time the surface will oxidise and go a uniform dull grey colour which to my mind is quite attractive.

(This is what they did with the aluminium catamaran in my avatar photo - her hull topsides are not painted - similarly the French Ovni, Maracuja and Cigale sailing yachts, amongst many others)
 
Tried both methods on heavily used aluminium parts (anchor winch body and mast lowering A-frame) . Both worked, although the etch primer tended to give a less smooth finish, but that may be just the make. The Hammerite way gives a very durable coat, especially the hammer-finish variety, since it apparently contains powdered glass. But most disappointed users tend to paint it on, and start to use the part after it has dried after a few days, like you do with ordinary paint. Usually, I plan Hammerite painting early on, put on a heavy coat or two, and let it dry for TWO MONTHS in a well-aerated garage. After that, it is almost as hard as hard as two-pack paint, and easy to clean.
 
Thanks for that, 'thalasa'. Unfortunately, with the boat already uncovered and due to hit the water in a week, I don't have two monthe drying time!
Next winter, perhaps?
 
Aluminium - fit for purpose?

Just a word of warning. Soft or half-hard aluminium has poor fatigue properties and, unless made from fairly meaty thickness, may fail in a short time with a vibrating generator up a mast. This kind of fitting is far better in stainless steel. If you are happy with your design then ignore what I say.
 
Re: Aluminium - fit for purpose?

I just got some anodising done for £5 approx, shop around. A company that does much anodising could poss put yours in at the same time as another job.

Try a few large mast companies
 
Re: Aluminium - fit for purpose?

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I just got some anodising done for £5 approx, shop around. A company that does much anodising could poss put yours in at the same time as another job.

[/ QUOTE ]

That sounds more like it... where did you get that done?
 
Re: Aluminium - fit for purpose?

Hmmmm.. well thanks for the warning, I'm using 5 mm ali for the main webs, with flanges folded over at top and bottom so hope it all should hang together!.

Nick
 
Chromate primers are used on Naval ships, submarines and aircraft so I would go for that. There is something called (I'm guessing the spelling here) Alu-chrom which comes in clear or coloured and can be used as both primer and touch-up for anodised surfaces.
 
The key to painting aluminum is corrosion control.

You have to remove the surface corrosion and etch the surface with a good primer wash. As soon as this is applied and wiped off, the corrosion starts immediately, so you need to be ready to apply a good zinc chromate primer immediately the surface is dry from the wash.

Then I would recommend a good 2 part epoxy primer (Awlgrip works), and then a two part polyurethane.

The conditions need to be controlled. No rain, no dew, no steam, no fog in the air between the primer wash through the curing of the primer--even better if you can do it all indoors.
 
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