What paint for Aluminum Propellers?

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hanjae

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After last season and the pitting I have found on my old props I now have a good pair of S/H Aluminum props to put on next season, I want to paint them with a good strong protective paint now and prior to going in the water?
These are on Volvo Penta sterndrives
What do you guys advise??
 
I used to etch then prime with 2 pack epoxy then coat with 2 pack poly. Lasted surprisingly well, but never more than 3 years without some bubling and a re-cote.
 
Trilux is an Anti Foul paint specialy formulated to protect Aluminium propellors, thats why our friend was getting 'Pitting' in his old propellor!
He was either using no protection or the wrong type.
You do NOT paint aluminium propellors with normal anti foul !
PS:- I do not work for International Paints, I like many of us learn the hard way called experiance!
 
I think there is some confusion between antifouling and protection of the metal here.
If Trilux is designed for aluminium it will probably be based on cuprous thiocyanate which will not allow the copper to react with aluminium. Most antifoulings are based on cuprous oxide which will most certainly react with aluminium.
However no antifouling will protect the aluminium from degrading in salt water. For this you need to etch and prime as someone said earlier.
On a propellor you really need a thin film coating to avoid affecting efficiency. Also a thick coat will probably be damaged by the forces from tip vortexes as the blades spin and get ripped off.
Antifoulings designed for propellors are invariably hard, non- eroding products, again to try to overcome the tip vortexes but they still usually breakdown at the tips first.
 
There was a rumour I picked up at SIBS that International are in the middle of developing a new ali prop protection/antifoul paint.
Wouldn't be available until after next season though......anyone heard anything more?
 
[ QUOTE ]
I think there is some confusion between antifouling and protection of the metal here.
If Trilux is designed for aluminium it will probably be based on cuprous thiocyanate

[/ QUOTE ] I think you are right about the confusion. The original question appears to be asking for a suggestion for a protective coating not an antifouling.

I don't know what coating is used on ali props. A powder coating perhaps. If so then not something that can be painted on!

Regarding Trilux. It is International's antifouling for aluminium and it does contain cuprous thiocyanate.
 
I have to endorse this view. I have struggled for years with my Alu prop, used expensive proprietary paints, etchings and all the rest of it, and still on liftout there are large areas of exposed and corroding metal! As soon as the paint skin is broken or scratched, the corrosion starts.

Last year the corrosion had gone too far so I bought a new 3 blade prop with teh usual black stoved painted surface. Added nothing to it just to see how it would last. Eureka - two seasons now with no paint loss or corrosion. A fair number of barnacles though. But I'm all too aware this surface will not last beyond the first ding!

The prop repair folks in Wimbledon reckon there's nothing you can do with alu props - just bang on some regular paint! I was sceptical, now I am converted.

PWG
 
To coat aluminium props : blast to Sa3 using Olivine, grade AFS 20 or 30, acid etch, followed by zinc phosphating, apply powder coating in temperature / humidity controlled baking oven. Post full cure of powder coating lightly abrade surface with wet & dry grade 240, apply 3 coats minimum of Prop-O-Drev. If all steps are correctly carried out, props are good for 2 to 3 years immersion in salt water, trust me, I'm a qualified coatings inspector in the oil & gas business.
 
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