Bonderite (alodine) or not?

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Bonderite (alodine) or not?

Postby ChuckStein » Thu May 31, 2018 9:24 pm

I came here looking for some expert advice.
My Al 6061 parts are not airplane parts, but I have a question.

Does alodine provide a better layer to prime to vs just a lye bath followed by nitric acid to remove smut IF I am using rattle can etching primer?

Or, if you only had 1k rattle cans what process and primer would you use to get a super bond to the AL?


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Re: Bonderite (alodine) or not?

Postby kennyw » Fri Jun 01, 2018 11:52 pm

Another skirmish in the primer-wars!

I wouldn't waste my money Alodining something I was gonna spray with self-etch primer. Self-etching primer does what it says, it etches. on virgin aluminum I don't use Alumiprep or any of that fancy stuff for self-etch primer either.

I've used SEM rattlecan primer with good results. Just clean well with isopropyl alcohol, wear gloves and make sure the primer and the parts are up to temp. You need 70+ degrees to get really good results.

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Re: Bonderite (alodine) or not?

Postby bruceh » Sat Jun 02, 2018 1:12 am

I gave up on the alodine about halfway through building the wings. The pieces got bigger than the smaller tail pieces and the toxicity of it got me generally against spending the time and expense trying to do brush it on or dip it prior to priming.
I found that just cleaning the aluminum with a scotchbrite pad and soapy water prior to priming worked just as well. As long as water doesn't bead up on the aluminum, you are basically good to go and shoot the primer.

I used the Akzo-Nobel epoxy primer and it dries quick and is impervious to just about everything. As I finished up building I ran out of that and switched to the NAPA self-etching primer for just a few little bits. The Akzo-Nobel stuff if you give it a day can withstand dimpling and riveting with no problems. The rattle can stuff needs a bit more time to fully set up, and even after that, it will still come off with MEK or a good scrub with acetone.

Unless you are going to make up a large vat of alodine and dip every piece, and deal with the toxic waste, and park your airplane next to the ocean daily, I would skip it.
Bruce Hill
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Re: Bonderite (alodine) or not?

Postby bullojm1 » Thu Jun 07, 2018 9:37 pm

I agree 100% with Bruce. I alumiprepped and alodined most of my empennage, but gave up when it came to the wing kit. My secret to success was:

  • Scuff with scotchbrite
  • Clean with water mixed with dawn dish soap.
  • Quick scrub with acetone soaked towel (helps absorb any water not already dried, and any oils)
  • Spray with AKZO

The ONLY place I wish I would of used Alodine was on the inside parts of my fuel tank. A fellow builder did this to his, and I thought it was a brilliant idea to prevent possible corrosion.

Avoid the rattle-cap primer at all costs. IMHO, all it does is act as a sponge for corrosion, as primer is meant to be a layer meant to assist the bonding of the topcoat to the base material. While AKZO is a paint to apply, it's pain and cost will pay off in dividends come the time you sell.
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Re: Bonderite (alodine) or not?

Postby kennyw » Thu Jun 28, 2018 8:42 pm

Meh, .... I'm gonna have to go find that issue of the RVator that had the multi-year primer comparison.

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