Finishing Aluminum?

[Chotu]

I have some 6106-t6 aluminum parts.

They got chalky and bumpy with uneven aluminum oxide bumps on them.

What’s the best way to finish 6106-t6 aluminum?

I gather it’s self etching primer and anodizing.

Which would you do? The anodizing shop said any imperfections would be telegraphed through the finish and amplified.

Are my parts not salvageable cosmetically?

I’m finding the frp structural sections I wanted to get are mostly unavailable, like air conditioning, Lexan, you name it. But aluminum seems to be available.

[Bill O]

Originally Posted by Chotu

I have some 6106-t6 aluminum parts.

They got chalky and bumpy with uneven aluminum oxide bumps on them.

What’s the best way to finish 6106-t6 aluminum?

I gather it’s self etching primer and anodizing.

Which would you do? The anodizing shop said any imperfections would be telegraphed through the finish and amplified.

Are my parts not salvageable cosmetically?

I’m finding the frp structural sections I wanted to get are mostly unavailable, like air conditioning, Lexan, you name it. But aluminum seems to be available.

Besides using a 5xxx series, you have a good grade of aluminum. Are these parts a visual or are they in the bilge, etc. out of sight?

We've had excellent results w/zinc chromate and epoxy paint on the windshield frame and bow sprit. (I forgot about your issue w/epoxy and there are other paints you could use instead of an epoxy)

Could use an aluminum epoxy repair putty like Devcon to fair your old pieces before etching/painting.

[Chotu]

Originally Posted by Bill O

Besides using a 5xxx series, you have a good grade of aluminum. Are these parts a visual or are they in the bilge, etc. out of sight?

We've had excellent results w/zinc chromate and epoxy paint on the windshield frame and bow sprit. (I forgot about your issue w/epoxy and there are other paints you could use instead of an epoxy)

Could use an aluminum epoxy repair putty like Devcon to fair your old pieces before etching/painting.

These are showcased pieces actually that will determine the fit and finish of the boat. They are vertical columns supporting various parts of the roof. They are what you look at all day long.

Do you think it’s a better idea to just buy all new aluminum, given it’s not too expensive? To avoid all the sanding?

I was hoping for the matte finished anodizing, but the anodizer said that is all determined by the surface of the metal when I bring it it.

So painting may me the way to go. As you suggest.

[Bill O]

New would probably be the way to go, then anodized.

The paint on the windshield frame was done early so no corrosion had set in before we painted. Our vertical bimini supports are unpainted sched. 40 aluminum pipe and have only minor pitting after many years. We didn't paint those since they are hand holds and typically we wipe them down often w/fresh water. (maybe once a year w/vinegar)

Actually I hate paint on aluminum since once painted, eventually it will bubble and need to be repaired. It does look good though when in good shape. Anodizing is probably better than paint, but it too will eventually wear off.

[Chotu]

Originally Posted by Bill O

New would probably be the way to go, then anodized.

The paint on the windshield frame was done early so no corrosion had set in before we painted. Our vertical bimini supports are unpainted sched. 40 aluminum pipe and have only minor pitting after many years. We didn't paint those since they are hand holds and typically we wipe them down often w/fresh water. (maybe once a year w/vinegar)

Actually I hate paint on aluminum since once painted, eventually it will bubble and need to be repaired. It does look good though when in good shape. Anodizing is probably better than paint, but it too will eventually wear off.

Ugh. The pandemic makes building a boat maddening. This is exactly why I’m trying to get the frp, so I can paint it and forget it. I guess I’ll keep looking.

[Chotu]

Here’s what the aluminum looks like now.

Easily salvaged or beat to buy new?

It hasn’t really changed in years, but it started looking like this quickly.

[Bill O]

Originally Posted by Chotu

Here’s what the aluminum looks like now.

Easily salvaged or beat to buy new?

It hasn’t really changed in years, but it started looking like this quickly.

A little hard to tell from a pic, but how deep are those black pit marks?

Have you ever wiped it down w/straight vinegar? A diluted phosphoric acid soln (most commercial alum. cleaners) would be a little stronger.

[Chotu]

Originally Posted by Bill O

A little hard to tell from a pic, but how deep are those black pit marks?

Have you ever wiped it down w/straight vinegar? A diluted phosphoric acid soln (most commercial alum. cleaners) would be a little stronger.

The black pot marks are actually mold. I just scraped that off with a fingernail.

The darker gray marks are the rough surface and it’s just ever so slightly different feeling than the rest of it.

I guess it could be removed easier than I thought. This is 40 strokes of sandpaper and a quick vinegar wipe. While I was posting.

Top left corner of the pole is where I tried it. It may not take so long to get it back to Perfect.

[Bill O]

Originally Posted by Chotu

The black pot marks are actually mold. I just scraped that off with a fingernail.

The darker gray marks are the rough surface and it’s just ever so slightly different feeling than the rest of it.

I guess it could be removed easier than I thought. This is 40 strokes of sandpaper and a quick vinegar wipe. While I was posting.

Top left corner of the pole is where I tried it. It may not take so long to get it back to Perfect.

That looks pretty good already. We use the fine abrasive pads instead of sand paper, but a fine emery cloth should also do the trick (could even try to wet sand w/vinegar)

[Tusitala]

have it really well and deeply bead blasted. I've seen a few chain plates done this way, and currently have a fairly old scuba tank with that finish. the other tanks we have were purchased at the same time and were painted. they're all blistering and peeling, while the blasted one still looks like the day we bought it. a trip to most dive shops, or even pictures online could give you an idea of how it looks. you probably could have it finish blasted after a deep cleanup if you don't like the texture and have it anodized, but I think the coarse finish looks good, especially since it ages well