Anodizing question

To help feed the boat kitty I import a very fine boat anchor from Tunisia. Arguably the best performing anchor made. They come in
galvanized steel, stainless and aluminum. My problem is the aluminum models are painted rather than anodized. While I have not received any complaints the paint tends to wear off fairly rapidly. I am thinking about ordering them bare and having them hard anodized locally.
The real problem is that each anchor is individually balanced by pouring lead into an open pocket at the tip. Would the exposed lead cause problems in the anodizing bath?
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Glenn Ashmore

I'm building a 45' cutter in strip/composite. Watch my progress (or lack
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On Tue, 13 Jan 2004 10:03:50 -0500, the renowned Glenn Ashmore

I don't think so, as they often use lead as the other electrode in anodizing. But talk to your supplier.
Best regards, Spehro Pefhany
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Yes. It'll need covered very well. I have doubts that hard anodising will actually do much. For fine sand, it may help. For pebbles, I doubt it'll do much at all.
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I do know that dip-brazed aluminum assemblies cannot be anodized. So I'd think a lead/aluminum assembly would be a problem. I think they told me any solder on the assembly would poison the bath.
Not all Al alloys are anodizeable. Yours may be cast or forged from an alloy that is suited to casting or forging, but is nonetheless one of the baddies.
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for the anodizing and you would probably melt the fixture holding the anchor in the bath. You can easily stop off the lead but you would have a bare Al margin around the lead.
You didn't mention what the alloy is, but casting alloys, especially diecast types don't anodize as well as wrought products.
Have you thought about powder coating, there are some really tough coatings available. Make sure the applicator is really good as there are some people out there that don't know what their doing.
Ed Angell
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Glenn Ashmore wrote:

I went to a local anodizer to get some of my bike engine anodized. They refused. They said they tried doing it before but it tends to pit cast aluminum, even the high grade stuff.
I heard the same from a few guys that use to work there.
It may have been their process as it was a place specializing in aircraft.
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Mark

N.E. Ohio
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Isn't an aluminum anchor a contradiction? ;)
And in which case you can send it to me as scrap :D
Tim
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Lead was used as the tank electrode in the plant I worked at, the solution was 10% sulfuric acid. I'd think it wouldn't be a problem except that the acid may get between the lead and the aluminum and loosen things up.
That said, anodizing isn't really a very durable finish for aluminum, epoxy powder coating is and will withstand salt water a whole lot better. We did powder coating as well, anodized test plates just melted away in the 1000 hour salt spray tests, epoxy powder coated plates just discolored a little with some breaks in the coating around the edges. Find yourself a good applicator, though. The test for a good cure was to take a nickel and rub the edge of it over the surface. A good coating would just have a light pencil-type mark, a bad cure would flake the finish off. I'm not sure how well it withstands impacts like hitting rocks underwater, but we could bend the trim we were doing double and the stuff didn't crack. Anodizing is like glass, it'll crack when bent or hit.
Stan
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Interesting points. I checked with a local aerospace metal finishing shop here in town and they agreed that lead would not be a problem in their baths.
OTOH, durability is a problem. This may not be worth the effort. Powder coating may be the answer but it would have to be a silver powder coat. Boaters are not likely to accept a bright orange anchor even though it might have some advantages when checking the set. :-)
Stan Schaefer wrote:

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Glenn Ashmore

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On Wed, 14 Jan 2004 17:03:15 -0500, Glenn Ashmore

Glenn,
White, They all like white.
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says...

I'm thinking there might be a *clear* powder coat.
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snip--

snop---
You should understand the differences in anodizing before making that statement. The typical anodized coating you may be familiar with is NOT hard anodizing. If it has been dyed any color, it is not hard anodizing. Hard anodizing will take the teeth of a new file with no effort. It is, indeed, durable, and can have considerable depth, unlike the two other types of anodizing.
Harold
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Anodizing is a fine finish treatment for something that needs to look pretty, but I don't consider it to be an abrasion or impact resistant finish. Thicknesses of .001-.002" and sapphire hardness aren't going to do much protecting when an anchor is dropped and set in rocky waters.
This is part of the problem with powder coating too, though not as hard/brittle, it isn't that thick. They do make it in almost any color, including clear, that you could want.
I think that is why thick coats of gummy enamel paints are so popular around salt water. They're cheap, can be easily repaired or refreshed and don't chip off.
>

Hard anodizing will take the teeth of a new file with no effort.

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