Sorry if I am late to the party, but see here ...
https://www.tinboats.net/threads/weeping-water-leak-due-to-corrosion-under-carpeted-bunks.41347/
https://www.tinboats.net/threads/weeping-water-leak-due-to-corrosion-under-carpeted-bunks.41347/
Interesting. So the ZC primer will help prevent further corrosion. Do you still have the boat? Hows it holding up? I was planning to avoid it just like @sonny1 did since TotalBoat makes an epoxy primer specifically for aluminum. I like the idea since it does help future pitting from happening.Sorry if I am late to the party, but see here ...
https://www.tinboats.net/threads/weeping-water-leak-due-to-corrosion-under-carpeted-bunks.41347/
Thanks very much for your response and link. glad to know the skim coat held up. I need to skim coat with something. Got my aluminum burs in the mail today, so Im gonna do some invasive surgery in the next couple days..Sorry if I am late to the party, but see here ...
https://www.tinboats.net/threads/weeping-water-leak-due-to-corrosion-under-carpeted-bunks.41347/
thanks for the reply kazzer. I like the cheap sandblasting setup there. I agree with your logic.Aluminum is always a problem removing oxide, because it instantly corrodes when exposed to air. When anodizing, the material is placed in a bath where the chemical dissolves the oxide and deposits a layer of zinc. As the process continues in the anodizing bath, the zinc is dissolved under water and the process of applying the anodize begins without the presence of air, so no oxide. Unfortunately, on a boat, this is impossible to do on a 'one off' basis. SO! Next best thing, in my opinion, is not to grind the surface, but to wet sand blast it. This will remove all the oxide, and lightly rough up the surface, so the mechanical bond of the surface will enhance the strength of the coating. Grinding is, in my opinion, a bad idea, because it won't get into the pits and removes a lot of metal. Blasters are pretty cheap on Amazon = look for = wet sand blaster kit for pressure washer $30. Amazon.com Use dry play sand with no lumps.
Blow the water off, and apply your coating ASAP. Yes, there will be a slight amount of corrosion, but that will be overcome by the roughness of the sand blast. www.caswellplating.com
thanks for the reply Wayne.I would wire brush it down good followed by a wipe down with M.E.K. or Acetone and then paint the area (or the whole boat even) with Zinc Chromate. Zinc Chromate stops corrosion dead in it's tracks and prevents any further corrosion. I live in Florida in a high moisture and salt environment and it protects my aluminum boats perfectly.
what not to do to your transom...View attachment 117881
Proper Preparation Prevents Piss Poor Performance. Words to live by! lolI have had outstanding success with both gray Marine Tex and JB Weld.
The trick is to wipe down with Acetone or spray with carb cleaner to remove any oil film, and then wire-brush immediately before repair. Then use a hair dryer or heat gun to warm the repair area immediately after application.
Warming it up thins the epoxy a little, and helps give a more secure bond into the "toothed" areas caused by the wire-brushing.
Do a small area at a time, focusing on getting the metal really clean. I've never had either one fail when prepped properly. They are permanent fixes for pitting like you show. Once dry, you can sand, prime and paint as desired.
If the spots are blown all the way through and are really big, there are other things to consider, but these will work for those, too. I might add a metal patch, if bigger than 1/4" hole.
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