Tarting up aluminium window frames

[ducked]

It maybe down to the severity of the salt environment. Pre treatment products are assessed on their ability to withstand hot salt water spray. They measure the resistance in hours. Chromate two components products go through this certification process. I have used these as pre-treatment before two pack epoxy primers then 2 pack polyurethane paint. The paint still bubbled within 2 years on my portlights. You also have to remove the anodising and have the product blasted. A lot of work for little gain

OTOH, MY procedure (which is mine, AFAIK) is very little work, is essentially free, and I'd bet is similar in gain.

Many Americans seemed to find those qualities subversive...

...which was nice.

 

[geem]

On motorcycle engine casings and cast wheels showing exfoliating corrosion I've just used my standard treatment for steel, abrade with crumpled aluminium foil using a small amount of vegetable oil as a binder.

On steel this produces a grey (if you remove most of the rust first, grey-brown if you dont) slow setting primer-like (though I havnt over-painted it and dont know if that would work) paint which seems to last quite well.

The oil is initially quite penetrative, soaking into residual corrosion, which seems to help stabilise corroded surfaces

Less experience on aluminium, but if bare it seems to darken it, though if its painted it tends to re-distribute the ground up remaining paint (and perhaps anodising, though I havn't used it on any anodised surfaces yet) and it can end up looking like a lighter tinted and probably slightly patchy version of the original.

(I should admit that my primary concern has been stopping corrosion and I've been indifferent to vehicle cosmetics. Remains to be seen if I maintain that attitude on the boat)

No experience of this treatment with boats yet, but I'll probably get some when I get back to the UK. My window frames were badly corroded, but may be too far gone to save, so nothing ventured...

Unsure whether I'll risk it on the mast, a big-ticket and relatively inaccessible item. Probably the mast step/taburnacle (which is galvanized steel) and maybe the boom

I've mostly used sunflower oil for availability and cheapness. Linseed would set quicker, as would tung oil. Canola or castor would be slower and thus probably less suitable.

An alkyd resin like Penetrol might be a superior binder but I wouldn't know how to get that in Taiwan so havn't tried it. Maybe when I get back to the UK.

You motorbike corrosion will be minor. It isn't suffering from hot salt water spray. The OP has been sailing in the Caribbean where the sea is particularly salty and hot.

 

[ducked]

I''m not sure of the validity of the apparent assumption that what works on a mild case of exfoliating corrosion wont work at all on a more extreme case. I'd think corrosion is corrosion, but you could be right

Then again, a previous owner was a surfer doode.
Surfer doodes park up next to the beach
Where there be spray
After typhoons
When there be big waves
In Taiwan
Where it be warm

Plus its been parked outside, certainly in my keeping, and probably all its life in Taiwan's chronic air pollution, much of which blows in from China, and it is about 40 years old.

Then again, I'm by no means sure, and didn't claim, that this WILL be effective on either the OP or my own window frames.

Then again, and as I've already said, the cost of finding out is soooo negligable (especially when compared to the schedule you outline above) that I think that I'd be daft not to try it on my windows.

Then again, while my window frames have probably only been subjected to the mild salinity and chilly temperatures of the North Sea, OTOH they have been subjected to the local atmospheric effects of Scotlands last coal-fired power station, an oil refinery, and an iron smelter.

Dont think you'll find much of THAT kind of shit in yálls tropical paradises.

 

[geem]

I''m not sure of the validity of the apparent assumption that what works on a mild case of exfoliating corrosion wont work at all on a more extreme case. I'd think corrosion is corrosion, but you could be right

Then again, a previous owner was a surfer doode.
Surfer doodes park up next to the beach
Where there be spray
After typhoons
When there be big waves
In Taiwan
Where it be warm

Plus its been parked outside, certainly in my keeping, and probably all its life in Taiwan's chronic air pollution, much of which blows in from China, and it is about 40 years old.

Then again, I'm by no means sure, and didn't claim, that this WILL be effective on either the OP or my own window frames.

Then again, and as I've already said, the cost of finding out is soooo negligable (especially when compared to the schedule you outline above) that I think that I'd be daft not to try it on my windows.

Then again, while my window frames have probably only been subjected to the mild salinity and chilly temperatures of the North Sea, OTOH they have been subjected to the local atmospheric effects of Scotlands last coal-fired power station, an oil refinery, and an iron smelter.

Dont think you'll find much of THAT kind of shit in yálls tropical paradises.

You are kdding yourself. The bike would need to by immersed in the sea several times a day for a month to suffer the same kind of salt spray that yacht windows see on an offshore passage

 

[Chiara’s slave]

All the same, how much worse will the frames look if they’re properly primed and painted? The only real solution is to replace them. Painting is just kicking the can down the road for as long as the paint lasts. I doubt it’ll last as long as it has on my spreaders, but a year or 2 it might.

 

[geem]

All the same, how much worse will the frames look if they’re properly primed and painted? The only real solution is to replace them. Painting is just kicking the can down the road for as long as the paint lasts. I doubt it’ll last as long as it has on my spreaders, but a year or 2 it might.

Maybe. My portlights were professionally finished in 2021. They were bubbling paint in 2024. We removed them, stripped off all fittings, blasted them, did a pretreatment, epoxy primer then 2 pack. This was done to the whole portlight, as I have found corrosion creeps around from the back if you don't do every part of the item.
I think once corrosion has happened, something changes in the structure of the aluminium that makes it very difficult to stop further corrosion, regardless of what treatment you do

 

[Chiara’s slave]

Maybe. My portlights were professionally finished in 2021. They were bubbling paint in 2024. We removed them, stripped off all fittings, blasted them, did a pretreatment, epoxy primer then 2 pack. This was done to the whole portlight, as I have found corrosion creeps around from the back if you don't do every part of the item.
I think once corrosion has happened, something changes in the structure of the aluminium that makes it very difficult to stop further corrosion, regardless of what treatment you do

Yes, hence my opinion that painting is a stop gap. Tidy them up while you look for the right place to get them remanufactured. We had new window frames 2 years ago. I didn’t give a thought about painting my own, as the boat was in a shed, and I could just take them out and have them copied.

 

[Sea Change]

These windows are set in to the cabin top- not sides- in an unusual and very French sort of way. I'm am trying to persuade SWMBO that we should just glass them over completely, but she likes the extra light that they bring. I'll see if she has changed her mind by the time we've rebuilt them.

 

[vyv_cox]

I wish I knew more about the composition of alloys. And how to weld them too!

I can't help with the second part but I know a good book that can tell you the first!

 

[vyv_cox]

Yes, hence my opinion that painting is a stop gap. Tidy them up while you look for the right place to get them remanufactured. We had new window frames 2 years ago. I didn’t give a thought about painting my own, as the boat was in a shed, and I could just take them out and have them copied.

When we lived in The Hague, which was up to 2003, I painted some aluminium plate on which to.mount my radar scanner. I used my favourite combination, Hammerite Special Metal Primer followed by their white Smoothrite (name may not now be the same.) I remember it particularly because I did it on our apartment balcony. That plate has been on the boat ever since and is almost as good now as it was when I did it.

The plate was very possibly 99% aluminium, half hard. I guess that some of the alloyed versions, 2xxx, 5xxx, 6xxx might not etch quite so well being more corrosion resistant.

 

[ducked]

You are kdding yourself. The bike would need to by immersed in the sea several times a day for a month to suffer the same kind of salt spray that yacht windows see on an offshore passage

Kidding myself of what exactly?
I think its worth a try
You apparently dont
Doesn't seem to be a problem.
You stick with

Sandblasting
THEN
Chromate two pack
THEN
Two pack epoxy primer
THEN
2 pack polyurethane
THEN
Bubbling
THEN
Scrap or repeat, which after all you are evidently already considerably invested in, though I think there's an Einstein quote that may apply

And I wont, because I arent.
And we'll see.