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Alodine industry experience question

LAMPSguy

Well Known Member
I am not asking about validity/preferences regarding doing this process, but rather asking if anyone has industry experience with it. I have found a place locally that will do the entire process for me for about the cost of just the chemicals (If I were to buy the powder in a large batch) so I see it as free labor and disposal of waste...better for my health AND sanity

My question is that they will do either the class 3 or 1A per MILSPEC. Specifically for the wing, the class 1A for max protection seems to make sense to me. Any flaws in my thinking?
 
I would definitely do it for the fuel tank components, and aluminum fuel tubing as well. Ethanol-laced fuel is more prone to aluminum corrosion and this would protect you against eventual exposure. I alodined all my fuel-wetted surfaces including the fuel tubing because I plan on running premium autofuel and I know I'll see ethanol in there.
 
I acid etch and alodine all aluminum in any aircraft repair/ build that I do in aviation. If you choose not to prime it will give you an excellent protection layer.

I acid etch, alodine, and primer everything.
 
Class 1A, unless...

I believe the major difference is in the degree of electrical resistance of the coated material. Class 3 is a thinner finish and offers less resistance. If that's the only issue, the decision would probably then hinge on whether conductivity is part of the requirement. If not, then Class 1A would provide better corrosion protection.

Sounds like you have a good situation going. Doing your own alodining is less than the best part of building. It's toxic, it stinks like nasty old sweatsocks, and it's always interesting to discover after a session that one of your rubber gloves has a pinhole in it. Guess how I learned about that last part - my indian name is "Yellow Fingers." It wears off after a few weeks.
 
I may be wrong, but I believe alodine is only a chemical batch, wherease annodize involves electrical currents -- similar sounding, very different in coating and changes to strength. This thread may be mixing the two terms. -Jim
 
I may be wrong, but I believe alodine is only a chemical batch, wherease annodize involves electrical currents -- similar sounding, very different in coating and changes to strength. This thread may be mixing the two terms. -Jim

You are correct.

John is talking about conducting electricity. The Alodine you purchase from Aircraft Spruce leaves a NON-CONDUCTIVE coating so it acts as an insulator. Touching a ground wire to an Alodine piece of aluminum would keep the ground open circuit unless you use the correct Alodine. I forget what class is which but one class of Alodine is conductive and the other is non-conductive or an insulator.
 
I am not asking about validity/preferences regarding doing this process, but rather asking if anyone has industry experience with it. I have found a place locally that will do the entire process for me for about the cost of just the chemicals (If I were to buy the powder in a large batch) so I see it as free labor and disposal of waste...better for my health AND sanity

I am not sure if you are contemplating alodining all the components before final rivetting or alodining the whole wing after fabrication but I am presuming the former.

The problem with commercial alodining of your wing components will be one of logistics.

The alodining company will most likely have a minimum batch cost so it will only make sense to do large numbers of components in one batch. As a result you will need to be able to identify all of those little match drilled left and right components so that you can clecoe them back into their correct position. But any pen markings will be erased during the pretreatment and alodining process so you will need to have a physical identification (indentations) of the items and have a record of what those markings mean.

But perhaps more important is that you will have to keep a complete inventory of every single item you get alodined. It is not enough to simply count the number of components (here's 130 components and I want 130 back). If you get less back than you gave them you need to be able to identify which components you did not get back.

I can assure you that in wiring up of all those individually shaped components onto racks for dipping it will be highly likely that some of them will end up in the bottom of a tank where they will stay until the tank is cleaned. The plant may be using a phosphoric acid pretreatment and alodine is a chromic acid so it is possible that your parts might be cactus by then (and you wont want to wait that long anyway because they may be lost elsewhere).

So that's probably the biggest problem...losing little one-off custom made parts that have already been match drilled and then trying to figure out what's actually missing.

You can complain to the treatment plant but your job will be worth stuff-all to them and is not commercially ongoing. So they just wont care if things are missing. It will be a nightmare for you but irrelevant to them.

Aloding is a very good process. Both Cessna and Piper now use it under all of their primers. But I recommend you do it yourself to keep control of your parts. Then you can do it in small batches as required. It's no big deal.
 
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Alodine on any interior surface is not necessary. Airplanes have been bare on the inside since the Wright Brothers and they are still good to go today. Now if you intend on applying primer/paint to something then yes, you need alodine. Not only does the alodine help protect the surface from corrosion but it helps the primer stick. There are self-etching primers you can use but in my experience they always fail.
 
My question is that they will do either the class 3 or 1A per MILSPEC. Specifically for the wing, the class 1A for max protection seems to make sense to me. Any flaws in my thinking?

Class 1A is definitely better for corrosion protection, but either would be fine. For our aircraft, even the conductivity of Class 1A is sufficient. We use Class 3 for electronics where EMI shielding or very sensitive ground planes are required. All structural components are Class 1A - even if they are to be grounded. I used a number of plating houses to alodine most of my -4 parts primarily for the advantages you cite. In addition, I had the plater also prime the wing and fuselage skins which were too large for me to easily paint in my booth. Sometimes I provided the paint, sometimes the plater did. I paid nominal and reasonable lot charges for the service and was very happy with the outcome and the time saved.

Good luck,

Dean
 
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