Painting problem - Help Please?

[Dougal]

Hi guys
For several years, i've been trying to paint my old aluminum (not polished) anchor windlass. It's cost me a fortune in etch primers, hammerite special primers and paint. Seems I always get problems of one sort or another. Usually rejection issues, no matter how I clean and prepare it. I just don't believe that Hammerite is what it use to be

Should i just bang some bloody cellulose car spray?

Be grateful for any ideas
Ta!

 

[prv]

Why do you want to paint it in the first place?

Pete

 

[StephenW]

I've faced a similar issue with aluminium wheels on a car - paint specialists LE Went recommended acid etch primer (2 part with activator) followed by cellulose paint. Have bought but not yet tried, but am hopeful as it seems a sensible combination.

I have had similar experience to you with Hammerite.

I believe paint film thickness is important to resist corrosive forces - good luck!

 

[Dougal]

Seems like a very strange question, but as I said, it's not polished, its just rough cast and looks like ****e;-) What else would you suggest then?

 

[Tranona]

If it is only cosmetic, leave it bare if you can't get paint to stick to it. If you really want a painted finish, take it apart and have the housing blasted, epoxy coated and then powder coated for a cosmetic finish.

 

[Big-Bang1]

Hi guys
For several years, i've been trying to paint my old aluminum (not polished) anchor windlass. It's cost me a fortune in etch primers, hammerite special primers and paint. Seems I always get problems of one sort or another. Usually rejection issues, no matter how I clean and prepare it. I just don't believe that Hammerite is what it use to be

Should i just bang some bloody cellulose car spray?

Be grateful for any ideas
Ta!

http://www.frost.co.uk/brands/por15/por15-por-20-heat-resistant-aluminium-paint.html

I know it says high temp but I have used this on the leg of an old outboard and three years later it still looks great! No problem with adhesion on to corroded alluminium. To be honest I really rate all of the POR-15 products. I have used the original black on diesel inboards and years later it looks as good as new. Yes it's VERY expensive but you get what you pay for - It really is that good!

 

[Dougal]

If it is only cosmetic, leave it bare if you can't get paint to stick to it. If you really want a painted finish, take it apart and have the housing blasted, epoxy coated and then powder coated for a cosmetic finish.

;-)))) I guess some folk just live in another world;-)

 

[Dougal]

Will check it out - thanks for that.

 

[Tranona]

;-)))) I guess some folk just live in another world;-)

Not living in another world. Just saying that as you have discovered is extremely difficult to get any brush applied coating to stay on rough cast aluminium - which is why it is often left unpainted. However, the process I described is similar to that manufacturers use when they do want to give such components a good cosmetic finish.

It is not expensive to have individual items done if you know the suppliers - I have had such work done on the trading estate about 2 miles away from where I live, but it does require you to strip the unit down to the bare casting.

Maybe the por 15 suggested will work (I have no experience of it), but I note that the second coat has to be cured at 150c, which might be a bit tricky on a windlass bolted to a boat!

 

[Big-Bang1]

You're right, it does say cure at 150'c. But, as I said in my post I've used it on an outboard leg and it has worked a treat and I'm pretty sure it hasn't made it to 170'c (I hope not anyhow ).
I can't think of a better alterntive that can be done in situe, but agree powder coat would be the best solution.

 

[prv]

Seems like a very strange question

Not really. People with aluminium boats generally find that getting paint to stick is difficult, so in many cases they leave the hull bare above the waterline (clearly some kind of antifoul is required below). The metal forms a self-protecting oxide coating, so painting is not necessary for protection. I'd have thought the same would apply to a windlass, though mine is plated brass rather than ally so I don't know first-hand.

Pete

 

[VicS]

;-)))) I guess some folk just live in another world;-)

You asked for ideas!

Tranona has given you not just an idea but probably the best solution. Very probably the advice you would get from a coatings technologist.

Grit blasting, etch priming and a chlorinated rubber paint might be an alternative. The paint technology lab where I worked at one time made a nice job of some badly corroded aluminium portholes by that method for a friend of mine.

The key to success is blasting to remove all the oxide from the aluminium. A soft grit will remove it without affecting the aluminium too much. Important to get the primer on promptly and correctly too.