Metal finishing Q&As since 1989

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Aluminum Boat Finishing

2000

Dear Sirs,

I am presently an aspiring boat builder and currently have an aluminum (5052) hull ready for finishing but have limited knowledge in the process. I would greatly appreciate any input that could tell me best steps to prep, primer, and paint.

I'm looking for the simplest, most economical method possible that will give a durable finish to salt water usage. I've thought of staying away from chromates if possible and using self etching primer instead. Thanks very much for any help someone might have.

Chris Kingrea
- Freeport Texas

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There are two ways to finish your boat, one is with a paint finish, which won't last very long ,the other is with a clear finish using a FLOUOROPOLYMER base coating, which will last far longer and give you better protection. A paint finish will last about two years at best and is to expensive, but it looks great for a while.

We leave the boat bare here and clear coat it, but you must have a good finish on it as every dent shows, and there is a trick to the grinding and sanding to get a good product. for a good paint job you must acid wash your boat with PHOSPHORIC ACID 300 GRAMS PER LTR, HYDROFLUORIC ACID 43 MLS PER LTR broken down to 9 to one, spray with a garden weed spray from the bottom to the top of the boat and wash of before it starts to dry or streak, paint within 4 hours. we have found epoxy acid etch paint to be the best ( kensai paints ) japan, may be available there, to be the best. P.S. put some detergent in the acid to make it foam, works better.this acid should be available from your alloy dealer ready mixed.

Richard lane
PHOENIX BOATS - NEW ZEALAND
2000

Ed. note: "Do not attempt this at home". Properly trained workers with proper personal protective equipment may well be able to do this safely, but individuals should not even think about using hydrofluoric acid. It's the one chemical that makes professional metal finishers shiver.

1) I'm not clear on what is meant by "broken down to 9:1" Is the proportion that the phosphoric acid is mixed to the other acid, or something else?

2) a "trick" to finishing? Just one? Is it proprietary or something you can share?

I've a 20 yr. old aluminum boat with painted topsides that could stand some spiffing up. It's in a heated shop and I've just completed gutting the interior down to the bare hull, so if I'm going to do it, there's no time like the present.

William Page
- Eden Praire, Minnesota, USA
2002