Alodine competed components
 

How would you, or is it even possible, to alodine exterior skins such as the wings, tanks, fuse and control surfaces after they are complete? Can it be brushed or sprayed on somehow?
I am thinking about corosion protection under vinyl wrap so it's not just bare aluminum.

Please let's not argue the merits of primers or paints. I'm just curious how it would be done and thinking forward to final finish.
And the insides are 100% primed.

Yes, that is what paint shops do prior to paint. Brush or spray on, dwell, and rinse. Remember hexavalent chromium is carcinogenic and hazardous waste, so protect yourself and the environment accordingly.

Prior to treating, the normal procedure is to etch or scuff.

Do you have to scuff the aluminum before applying vinyl? If you don't, you would at least have the alclad for corrosion protection under the vinyl.

Alodine process
 

Question 1.
So you could build a wing or fuse rotisserie so the surface is relatively level and brush a coating on leave it the prescribed time then rinse?

Question 2
How do you protect the environment when you rinse it?

Question 3
Will a paint fume respirator work or is a fresh air system required? I have a good respirator and change cartridges on schedule.

Scuff
 

From what I've read, it adheres best when the surface is very smooth like bare aluminum so alodine would be a protection. No scuffing.
Primed surface is supposed to be sanded smooth.
Total rookie opinions. I know next to nothing. Just started my research.

Alodine
 

I alodined the inside of my fuselage by de-greasing with an etch cleaner and scotch brite pads, water rinse, then applied alodine solution with a spray bottle. Let it set for 10 minutes (don't let it dry), then clear water rinse followed by rinse with RO water followed by blow dry with compressed air to get most of the water off. I followed with a light primer coat, but understand that is not what you are doing. I would think the outside could be done similarly. There is no fume from Alodine, just mist from the spray application. I used a standard paint respirator. There were more fumes from the etch cleaner.

Prior to applying alodine the surface of the aluminum must be made water break free. You will need to scotchbrite the surface to achieve this. Alodine will not "take" to Alclad. The easiest way to get a good conversion coating is to place a paper towel on the surface then saturate it with the alodine. Be sure to smooth out any air bubbles and don't leave it on for too long or it will turn the aluminum very dark or "burn" the metal due to excessive oxidation. Applying alodine by brush or spray bottle only works when the surface has been prepped very well, and even then it sometimes hard to get the desired results since it tends to run off.

On other large projects I just used a normal hand spray bottle somewhat like a spray gun to apply the alodine and it works just fine. The hard part is ensuring it didn't end up in the waste water system.

I have seen other people brush it on too.

We use a "weed sprayer" at work for alodine.. You know the container you pump up with air and your favorite weed killer, and spray down the fence.

As long as you rinse out the container and pump after alodining, it'll work for a long time.we burn through one a month but we etch and alodine 3 to 8 airplanes a month. And we don't rinse out the container or pump.

Does Alodine continue to corrode joints when used on finished assemblies?
 

A fellow chapter member, who is a college engineering professor, is adamant that Alodine (Bonderite) is a strong acid that will continue to erode within the joints when applied to finished assemblies. He says it is only designed for individual parts and that, if used on finished assemblies, it will penetrate joints to the extent that it cannot be fully rinsed out. That?s apart from the nastiness of the stuff itself.

His argument sounds persuasive, especially when you see the TDS advises avoiding all metal containers. Yet I read here that this is SOP for aircraft painters. I see Homebuilt Help also has a Youtube on the procedure

I really want to use this method, having lately chickened out of wrapping over bare metal here in my maritime environment.

Does this argument have any credibility?