Aliminum

What you have on your hand is what we call chalking. It's caused by age and weather. Your aluminium from the picture still looks in good shape. Just because it is chalking doesn't mean it will soon be bare metal. It could last a few more years. Just give the aluminum a good scrub to remove the chalking if it bothers you. If it is too far gone and you see bare metal there are primers and paint made for aluminum. Don't panic if you see bare metal. Aluminum doesn't rust. It corrodes and forms aluminum oxide which protects the aluminum from further corrosion. So you don't have to run out right away to buy paint.

Have you contacted the manufacturer to see what primers and paints they recommend?

No idea who the manufacturer is - we are not the original owner. Yes, in spots it goes down to the bare aluminum. This is exactly what happened on our front storm door a few years back.

Question...once I decide to repaint..must I get all the paint off or just whatever wipes off? Should I wipe with alcohol..or a thinner etc. You mentioned an aluminum paint. Does it come in a spray or would it be best to brush it? Does it require a primer?

There is not much to paint but a lot of prep...I want to do it right. My front door is good but under cover; again I just removed the glass insert, wiped the door down with water/soap, then water, then alcohol, then water. I then just sprayed it with Satin Rustolium.

Locate the company that built the sunroom. See if you can get touch up paint. If you cant, then try to match it as closely as you can. No reason to paint the entire thing. Lots of paint chalks. Years ago, they used to call that self cleaning. Just touch up the spots as needed and enjoy the sunroom.

Its 25 years plus old with no sticker anywhere as to the manufacturer.

I was home at lunch and touched 3 places, one on each side...all 3 sides are yielding chalk. If I start wiping down, I will see areas of bare aluminum.

I might tackle this one side at a time perhaps spring/fall/following spring.

Again, I will clean it but should I use some paint thinner or something or just wipe off whatever comes off with soap and water and then repaint.

Again, primer? Rustoleum? Aluminum paint? Brush? Spray? Thoughts...

This might be a fall project. Anywhere and everywhere is 'chalking'. It seems to come off to bare metal. So I again ask, is there a thinner or something to use to clean everything..if down to bare metal so be it...before applying a paint designed for aluminum. Seriously, I tried this in 6 areas..my hand comes out white each time...and if I keep wiping the same spot...white keeps coming off...I always wondered what the smear stuff was when I washed the windows...its the darn paint coming off onto my paper towels as they hit the edge and then smears onto the window....