What's the best paint for aluminium rubbing strakes?

[Bertramdriver]

The Bertram was cursed with very prominent all round aluminium rubbing strakes when built. Originally powder coated battleship grey they probably looked quite smart. However time has passed and the effects of rain, salt water, UV and general Med abuse has turned them into a rather unpleasant pox infected mess.
Underneath the metal is pitted but still sound.
So far I've tried two pack polyurethane. It's too hard and the daily expansion/ contraction in the med heat means it just flaked off. Then I moved on to Hammerite, let it dry and flaked it off with my fingernail. Then Plastidip Hard which is sold as an automotive paint. It stays on ok and does not flake but is relatively soft, so any hard contact tears it off as a sheet.
Single pack polyurethane is next to try.
Any other suggestions?
Don't even think about replacing them with rubber, wood or rope. The cost would sink me.

 

[Tradewinds]

I've used this and it's very good IMO.

Worth buying a can to try?

http://www.metateclimitedonline.com/product/aluminium spray

 

[TradewindSailor]

I would remove all the paint and leave bare. Why paint rubbing strakes anyway? Come to that, why paint aluminium?

If you do want to paint aluminium : the secret is to etch the surface first with phosphoric acid ..... try Alumiprep .... and then paint it soon afterwards. A little goes a long way. Look up the instructions for Alumiprep :
http://www.solvents.net.au/index_htm_files/ALUMIPREP 33 (169315).pdf

There are several other products of the same ilk.

As for paints ... a good quality single pack polyurethane would work ... and you can touch it up when it gets damaged.

 

[vyv_cox]

Yes, you need either to pre-etch it or use an etch primer. I have had great success with Hammerite Special Metals primer on aluminium, zinc and bronze. I did my radar scanner mounting, an aluminium plate, with it well over ten years ago and it is still good, with white Hammerite on top.

 

[ghostlymoron]

I'm not impressed with the 'new' Hammerite formulation. If you did it over ten years ago Hammerite was completely different and used proper thinners, now it's water based and nowhere near as good. I bought some Aldiddle metal paint a while ago but haven't used it yet (like a lot of stuff I get from them) hoping it would be like the 'old' stuff.

 

[prv]

I bought some Aldiddle metal paint a while ago but haven't used it yet (like a lot of stuff I get from them) hoping it would be like the 'old' stuff.

The problem is EU rules limiting the contents of "consumer" paint. Aldi is German so also likely to comply. You need to find some old stock, non-EU grey import, or stuff meant to be sold for pro use.

Pete

 

[estarzinger]

I have have pretty good luck with this stuff: http://www.yachtpaint.com/LiteratureCentre/primocon-info-usa-eng.pdf

But you need to get the metal under it pretty clean before putting it on.

 

[LadyInBed]

I would use stainless steel wire wool, then rub it over with an oily rag occasionally.