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What's next best to Alodine?

benjam

Active Member
Hi All,

I am having difficulty obtaining Alodine in Australia.

What would be next best?

Why can't I just use aluminium penetrating primer from the hardware shop?

Is self-etch primer the same as etching primer?

This stuff is doing my head in and I am only just starting!
 
G?day,
I use Prekote. It is an environmentally friendly, strong detergent that creates a super clean surface, and perfect surface for primer to stick to. It works on having a good primer coat to prevent corrosion.
ASAP Spares at Caboolture sell it.
 
2K etch primer

Any brand will do. That is what commercial fabricators of semi-trailers use. Just Scotchbrite, Solvent wipe and spray.
 
Aviation Parts and Equipment

Hi Ben,
Contact Paul at Aviation Parts and Equipment. They are based at Bankstown and stock Alodine, and can ship if needed.
Have fun building the 8.
Cheers,
Joe
 
Hi All,

I am having difficulty obtaining Alodine in Australia.

What would be next best?

Ben-

There is a company out of Chicago called Sanchem that makes two products that are conversion coatings much the same as Alodine. The products are much more environmentally friendly than Alodine, in that, they are chromate free and for that reason you may be able to obtain them in Australia.

Sanchem makes a product line called SafeGard. The SafeGard conversion coating products each have quite different application methods ... the products most suited for our application are Sanchem CC-6100 and Sanchem CC-3400. I used the CC-6100 on my project.

Below is a link to the Sanchem web site with the SafeGard product line shown.
https://www.sanchem.com/aluminum-pretreatment-conversion-coatings.html

Happy building,
 
Hey Ben,

You've opened a can of worms! You'll find everyone has an opinion on surface prep and priming :). You'll have to read up on different processes and find which process fits in best with your mission. The generally accepted 'best' process for corrosion protection is alodine + prime, but this process adds time to the build, and some argue that it provides a higher level of corrosion resistance than our airframes will ever need. A floatplane would be a different story of course.

My process: lightly scotchbrite all surfaces to be primed (the shiny alclad layer helps with corrosion protection, you don't want to remove this), clean with prepsol or similar, and then prime with an etch primer. I use a spray gun for large skins, and aerosol cans for small parts. I use Wattyl Super Etch, which is easy to get hold of in Brissy (Wattyl Industrial in Rocklea usually have it in stock).. it dries to a rock hard finish if you give it a couple of days to cure properly. I've left some test pieces exposed outside over the years and no signs of corrosion yet..

I do however alodine structural angle pieces before priming, as these parts lack the alclad layer and are less resistant to corrosion. (HS-810 and HS-814 for example).

Enjoy the journey!

Hugh
 
Ben-

There is a company out of Chicago called Sanchem that makes two products that are conversion coatings much the same as Alodine. The products are much more environmentally friendly than Alodine, in that, they are chromate free and for that reason you may be able to obtain them in Australia.

Sanchem makes a product line called SafeGard. The SafeGard conversion coating products each have quite different application methods ... the products most suited for our application are Sanchem CC-6100 and Sanchem CC-3400. I used the CC-6100 on my project.

Below is a link to the Sanchem web site with the SafeGard product line shown.
https://www.sanchem.com/aluminum-pretreatment-conversion-coatings.html

Happy building,

John, this is great info -- thanks. I was not aware of these products.

Pacific Coast Composites sells AC-130 sol gel and BR-6747 primer in small quantities. This combination is really the modern gold-standard for aluminum pre-treatment and corrosion protection/adhesion promotion. But I will check with Sanchem to see how their prices compare.

Alodine is hexavalent chromium folks, DO NOT allow it to enter any watershed or ground water. Nasty stuff.
 
Thanks all for your replies.

I will follow up on the aussie suppliers first, so as to avoid the 3week shipping wait (not to mention the cost of freight!)

Thanks for taking the time to respond.
 
So just to confirm:

1. Prep the aluminium via deburring and scouring all the webs and flanges;
2. Apply the prep: alumiprep and alodine, or clean with Bon Ami, or Prepsol, or CC6100;
3. Apply the etch primer.

This process is applied to every aluminium component during the build.

On exterior surfaces, the final top colour coats would also be applied.

Have I got this correct? Am I missing anything?
 
Or also could clean with prekote.

Personally, after having used it quite a bit, I think PreKote is just a placebo to get you to scrub parts vigorously with scotchbright. I think you would get the same result with plain water.


It is not necessary to do this whole treatment to every aluminum component in the airplane, unless you operate near sea water. Anything that is alclad should just be washed and etch-primed, or just left alone.

For ordinary service (fairly dry climate, hangared), non alclad parts, I think you can just wash with soap and water (or use PreKote if you want) and a vigorous scotchbright scrub, and spray with etching primer.

Fay surfaces (surfaces that mate intimately with other parts) that will be exposed to the elements deserve the full treatment -- AC-130+BR6747 (or AC-130 + AKZO) or CC-6100 + CC-3400. We do this primarily where aluminum parts are bonded to composite parts, and for intimately joined aluminum parts, like spar caps to webs.

External surfaces that will be painted - follow paint manufacturer's instructions. This is the application that PreKote was developed for, and is probably fine, but again I don't know that it actually does anything.
 
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