Aluminum windows

[rherten]

Hello, I have aluminum window frames on my fibreglass trawler (NP36) and the paint on the window frames is blistering pretty badly. I am likely going to sand these down and re-paint with a Tremclad type paint, but hoping somebody has some experience and/or suggestions. Do I need to sand the entire frame down to the aluminum or just the blistered areas and rough up the remaining area? Would I be OK with a Tremclad if I can find a close enough match, or is there something specific and/or primer I should be using? If I do need to colour match, where would I go for that?

Also the screens in some of the frames need to be replaced. There seems to be lots of info on the web which makes this task look fairly straight forward, but any advice would be appreciated.

Thanks!

 

[Comodave]

Welcome aboard. There have been several threads recently about painting aluminum frames on windows and doors. Do a search either by Google or the search function here. Google may be easier though, just include the website in the search parameters.

 

[rherten]

OK will do. Thanks

 

[FF]

Rustoleum has a great aluminum primer , its so good it will prime galvanized , usually the hardest to stick paint to.

 

[Choices]

Traditionally painting aluminum is a three step process.

I prefer to sand till white finish, wipe with degreaser, then immediately apply aluminum sealer coat, like within thirty minutes or less.

Aluminum oxides very quickly. If you can get it sealed quickly you will have a chance of it lasting years.

After sealer comes primer then top coat.

I have used Awlgrip with good success, brushed and sprayed.

Most frames are powder coated. Due to cost, few powder coaters use the three step process, some only one.

Once corrosion starts under powder coating it must be stripped to bare metal and reapplied.

The really right way to fix aluminum windows would be to pull them and have them military spec anodized, then painted or powder coated. Should last a longtime. Hatteras did this process.

It is a lot of work, do do it right and do it once.

This is why Nordhavn went to frameless windows. Imagine a $3-4 million dollar boat with blistering windows.

We have the technology to 3D print window frames out of fiberglass, carbon fiber, even stainless steel. I even considered making them out of fiberglass extrusion.

Was not much interest due to cost.

 

[rherten]

Thanks for the advice!

 

[Arc]

I did a big job on a express boat. You will find corrosion under the weather strip of the glass so you must strip the frames completely. I started by 80grit scuffing . Then paint stripper. Then hot water power washing. Final sanding . Lacquer thinner wash. Then immediately prime with Variprime. Very important to wipe and spray. Finnish off with Awlgrip. 8 years later still perfect.

 

[ghost]

Four steps, not three. Do the first three steps, then the fourth step is to strip it all off and do it over in 6 months while focusing on the prep and priming progressively more seriously than the first six or seven times until you start to get it right.

Keeping paint on aluminum is no picnic.

 

[Comodave]

It is very difficult to get all the corrosion off the aluminum and if you don’t it will just come back again.

 

[BruceK]

In my experience, to prevent oxidization, the etch primer has to go on the instant you finish sanding. Or before, if that were possible.

 

[Choices]

Arc brought up a good point.

Once a aluminum window starts bubbling, it breaks the gasket and adhesive seals, both sides, everywhere.

So it leaks down the walls from the glass and under the frame. Big time problem.

Must be completely pulled and rebuilt.

None of these guys are exaggerating, they have probably all done it a few times, so find someone close who has learned the process and pick their brain.

 

[Island Cessna]

Welcome aboard. There have been several threads recently about painting aluminum frames on windows and doors. Do a search either by Google or the search function here. Google may be easier though, just include the website in the search parameters.

For starters I clarify that I have never painted any aluminum so have no experience, nor have I done any research into the techniques.

I have however owned a Cessna airplane which was just over 40 years old when I bought it, and was 59 years old when I sold it. It had a couple of adventures before my ownership that resulted in a small part the aluminum skin being replaced. These panels had newer paint, but the majority of the paint was factory original. The plane had spent its entire life hangared or tied down within sight of salt water in the PNW, so while not as exposed as a boat, it had lived in a humid marine environment.

After 59 years 90% of the paint was original, and though a bit faded and worn in spots was still intact, securely protecting the underlying aluminum from the elements. Remember this was not 21st century paint, it was available in 1960!

Is there something to be learned from airplane paint materials or processes? Airplane painting is veeerrrry expensive, but for a window frame perhaps a good option.

Bill

 

[mvweebles]

Good observation Bill (Island Cessna). Back in 2004 or 2005, PAE introduced the newer lines of boats with the N55 and later N47. Both of these used aluminum framed doors and windows that within a few years showed signs of oxidation with bubbling paint that looked like crap. Really turned me off on these newer generation Nordhavns.

I refinished a plain aluminum sailboat mast about 20-years ago. It was a pain in the butt to sand, etch, prime, and paint (roller). I had the boat for about 5-years and it held up very well, but who knows longer term. I certainly understand the cost aspect.

Peter

 

[cardude01]

My boat has aluminum frame windows that are powder coated. They were all starting to bubble, so I sanded them all down to bare aluminum on the exterior. I coat them with some woody wax every now and then to keep corrosion down. Seems to work OK.

 

[Choices]

Airplane paint was probably Dupont's Imron.
Very tough paint.
Superior IMHO to Awlgrip, but hard to find and usually restricted to trade and one gallon quantities.
Way more than you need for windows.