Treatment for aluminium tube

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chris-s

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Further to my whisker pole project, the length of tube arrived this morning. Obviously it’s not anodised so what’s the best way to protect it?

Left to my own devices I’d consider hammerite special metals primer and a bit of something for topcoat.

Chris
 
chris-s said:
Further to my whisker pole project, the length of tube arrived this morning. Obviously it’s not anodised so what’s the best way to protect it?

Left to my own devices I’d consider hammerite special metals primer and a bit of something for topcoat.

Chris
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The "best way" would be to get it anodised

Or find some other use for it and buy a length that is anodised
 
You may find a company offering Powder Coating local to you. This is powdered paint, electrostatically deposited onto the metal then heated in an oven to make the paint film. Tell them that it is for an outside job and they should use the right type of powders. You may find taking it to them and offering cash gets a good price. Ask them what colours are going through regularly and chose one of those for best economy and use of fresh powder.
My local place would be about £40 and either black, white, silver or orange. I had a jib stick done in orange and the gloss is still there 3 years later.

Note that I do not mean plastic powder dipping, which is another thing and not a painting process
 
Anodising is the long term answer.
Where that's not worthwhile, anything from a squirt of aerosol paint upwards will work for a while.
Bits that get wear can sometimes usefully be protected by glue-lined heat shrink, stick-on fabric or even simply wrapping with tape.

Generally it pays to buy anodised tube...
 
The other answer is, don't bother! Anodizing only increases the thickness of the oxide layer that forms spontaneously on aluminium anyway, making it more resistant to wear. Aluminium yachts are often left unfinished; it's difficult to make paint stick and the natural layer of oxidation is plenty in non-wearing parts.

Basically, aluminium is highly reactive, and it forms a layer of aluminium oxide (same stuff as corundum) almost instantly on exposure to air. This protects the metal from further oxidation. Anodizing simply increases the thickness of this layer, improving its resistance to mechanical damage. Obviously this layer can be mechanically damaged resulting in further oxidation, but as long as it's intact, it will protect the metal. The main concern is electrolytic corrosion, resulting from contact with dissimilar metals - in almost all cases, aluminium will corrode preferentially to other metals, as it is one of the least "base" metals in common use. That's why it is recommended to isolate aluminium parts from other fittings by using things like Duralac, or using very inert metals such as monel metal.

I'm not recommending this - it's way too expensive - but if you REALLY want to protect Aluminium, the company my wife works for provides a VERY resistant engineering quality coating - see Keronite coating!
 
AntarcticPilot said:
The other answer is, don't bother! Anodizing only increases the thickness of the oxide layer that forms spontaneously on aluminium anyway, making it more resistant to wear. Aluminium yachts are often left unfinished; it's difficult to make paint stick and the natural layer of oxidation is plenty in non-wearing parts.

Basically, aluminium is highly reactive, and it forms a layer of aluminium oxide (same stuff as corundum) almost instantly on exposure to air. This protects the metal from further oxidation. Anodizing simply increases the thickness of this layer, improving its resistance to mechanical damage...
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Nice theory, but in practice, bare aluminium often goes furry once it can even smell the sea, and it can crumble away without ever producing a useful protective oxide layer. Obviously 'aluminium' covers a whole spectrum of various alloys, but I've never found bare ali tubes to be a good idea.
It also makes a mess of everything it touches.
The upside is, once it's weathered, sand off the loose crud and it paints well.
 
Yes, car wheel lacquer from Eurocarparts is ideal if you really feel the need. You could even spay it crome/silver/black/colours first using their products. I redid my alloy bike gearbox cover successfully.
 
What grade of aluminium is the tube?

The corrosion resistance of the different types of aluminium varies enormously.
 
Zinssers allcoat exterior sovent based ! this stuff can be virtually painted on anything, including plastic, formica, aluminium, galvanised, steel, wood, bitumen, tar, brick, concrete etc..
Would liken it to the original Hammerite, but lots better.. Its a primer, undercoat and top coat in one needing no preparation.
Have used it on galvanised, aluminium, a steel ship ,( 3 years later and with just one coat nothing is peeling) channel marker buoys, woodwork and ive never used another paint like it..
It dries a bit too fast, like 10 mins touch dry so you dont really get a great finish on doors as its impossible to keep a wet edge.
It has a very powerfull smell, like acetone so dont use it indoors but what a great paint !
Painting a 54 metre long cor 10 steel yacht mast next week with the water based version. will be interesting to see how it compares to the solvent based but have great expectations with this 2 coats fits all type paint.
 
LadyInBed said:
TV Aerial / Washing line pole grade seems to resist corrosion quite well :)
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This type of general aluminium can often be from the one series such as 1100. This has reasonable corrosion resistance, a long way short of the better marine alloys, but not too bad.

On the other hand, it can be formed out of one of the two series aluminums such as 2011. These are often used in non marine applications and have very poor corrosion resistance.
 
Use it to prop up your runner beans then buy something worthwhile for the job as you should have done in the first place. Or use it for what you intended, then watch it and learn why not. Rule 1. Only do a job once.
 
AntarcticPilot said:
The other answer is, don't bother! Anodizing only increases the thickness of the oxide layer that forms spontaneously on aluminium anyway, making it more resistant to wear. Aluminium yachts are often left unfinished; it's difficult to make paint stick and the natural layer of oxidation is plenty in non-wearing parts.

Basically, aluminium is highly reactive, and it forms a layer of aluminium oxide (same stuff as corundum) almost instantly on exposure to air. This protects the metal from further oxidation. Anodizing simply increases the thickness of this layer, improving its resistance to mechanical damage. Obviously this layer can be mechanically damaged resulting in further oxidation, but as long as it's intact, it will protect the metal. The main concern is electrolytic corrosion, resulting from contact with dissimilar metals - in almost all cases, aluminium will corrode preferentially to other metals, as it is one of the least "base" metals in common use. That's why it is recommended to isolate aluminium parts from other fittings by using things like Duralac, or using very inert metals such as monel metal.

I'm not recommending this - it's way too expensive - but if you REALLY want to protect Aluminium, the company my wife works for provides a VERY resistant engineering quality coating - see Keronite coating!
Click to expand...
Ovni Yachts are not anodised & seem to survive ok
 
chris-s said:
Further to my whisker pole project, the length of tube arrived this morning. Obviously it’s not anodised so what’s the best way to protect it?

Left to my own devices I’d consider hammerite special metals primer and a bit of something for topcoat.

Chris
Click to expand...
I have an untreated aluminium 4m long 50mm dia spini pole (no idea of the ally grade) that has lived hanging in brackets off the deck on my stanchions for at least 30 years. Apart from a regular fresh water rinse and an annual service with lubricant it is as good as new.
 
Old Harry said:
Ovni Yachts are not anodised & seem to survive ok
Click to expand...
Proper marine grade should be good for 50 years. I had an aluminium boat for 18 years.. Keep them bare and as already mentioned, they oxidise on the surface and protect themselves, but add any other metal (contact) and they vanish before your eyes !
 
Hadenough said:
I have an untreated aluminium 4m long 50mm dia spini pole (no idea of the ally grade) that has lived hanging in brackets off the deck on my stanchions for at least 30 years. Apart from a regular fresh water rinse and an annual service with lubricant it is as good as new.
Click to expand...

Spinnaker poles are often formed from one of the six series aluminiums. If it was made 30 years ago probably 6061. This grade has good corrosion resistance (not quite excellent) and is considered a “marine grade”. It is not suitable for continual salt water immersion, but has a reasonable life above the waterline without any protection.

I am hoping the OP has one of the six series, in which case it would be fine (as your experience shows) without any additional treatment, providing dissimilar metals are isolated.
 
Thanks for the replies, the usual expected mix. I’m quite intrigued about using it for runner beans, can’t stand them tho.

Sounds like nothing or a simple coat of paint/lacquer and it will outlive the time I expect to own this boat.

Cheers!
 
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