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Alodine and cleaning questions please

swift12

Well Known Member
Hi I am NOT using alodine for most things as I’m wanting to avoid hexavalent chromium during my build however I have a small amount sealed in a 20 litre pail in its gallon container. I would like to protect my non alclad doublers, horns, brackets etc.

Is it easiest to brush it on or dip it….after doing these parts you have to wash off with water and how do people catch the rinse water to dispose of it properly. Obviously not wanting to really have it anywhere near me and certainly not all over my property. I have rubber gloves, a hazmat suit, respirator etc….want to get all these tail parts done in one go.

I am NOT using akzo zinc chromate. Same deal as above.

I am using wattyl super etch using my own gun with rattle cans for small touch Ups.

I started with Stewart systems ekopoxy but really did not get on well with it. I do have their eko clean which does a great job of de greasing and cleaning the Ali.
Any reason the water based eko clean would be no good for a single pack epoxy primer like super etch? I am not etching with the eko etch I have as the super etch does that itself…..after scotchbrite and cleaning.

Not looking for a primer war here….just choosing not to go near the really poisonous stuff for personal reasons any more than I have to….just asking the basic questions above.cheers.
 
I would say dipping would be easiest and fastest with less chance of getting any on you. For rinsing, you could dip in a container of clean water. Only needs to a container big enough for your part.

In general, the cleaner and better etched your part is, the better your alodine treatment will be. For best primer results, try and get your part primed within 24 hours.
 
Alodine

I use those clear plastic food containers or heavy zip bags depending on the part. I scuff with maroon, drop in a bag with alumiprep for a minute or two. Move to a rinse container. Drop into bag with alodine for a minute or so. Move to rinse. I can stretch a few teaspoons across several parts. If you're careful, there's no waste. All waste including rinse baths are poured into a gallon bottle till it's full then it goes to Haz Mat for disposal.
When I Alodined the outside of the airplane, I set up a sluice. Old shower curtain draped underneath and tilted so the waste ran into a storage bin. The bin was left in the barn till it evaporated down to a gallon then transferred and taken to Haz Mat.
PPE should be used as you mentioned.
 
Thank you I’m not sure if I can get alumiprep as it does not seem to exist in NZ.

Is that like eko clean? As in does anyone think that is an acceptable alternative for non water based epoxy based primer?

Cheers for the methods….I’ll set up something to catch everything and try to use as little as possible in the “bag” method. I won’t do any alclad parts but the elevator doublers are quite long….so the bag method won’t work there I guess.

I will treat, dry and prime in the same day.
 
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Alumiprep

Thank you I’m not sure if I can get alumiprep as it does not seem to exist in NZ.

Is that like eko clean

Not sure. Alumiprep is an acid. I've had equal results scrubbing parts with maroon scotchbrite and powdered cleaner. One less chemical. Wash in the sink. Bon Ami is preferred but Comet and Ajax work. Just make sure to rinse well. The latter two have sodium hypochlorite (bleach). Not good to leave on aluminum.
 
Any place that sells Alodine 1201 should also sell Alumiprep 33.

Its offical name is: Henkel BONDERITE C-IC 33 AERO ACID DEOXIDIZER known as TURCO ALUMIPREP 33

It's basically dilute phosphoric acid. From the MSDS dated 2017:

Phosphoric acid 10 - 30 %
2-Butoxyethanol 10 - 30 %

plus a couple of percent of other things in water.

If you are really having trouble finding it, one of the aluminium-brightening care care products could substitute, since they also are basically dilute phosphoric acid.

For corrosion protection, there is no need to prime or paint after alodining, but if it's in an area likely to suffer lots of abrasion or impacts it couldn't hurt to prime. Also, even if the alodine surface is scratched, it will still provide some galvanic protection.
 
Thanks again for the responses. I’ll search for the acid solution in another form. I’ll ring Henkel in nz to see if they have the product. I was given the alodine solution (most of a gallon) so have not dealt with any resellers. I won’t prime the rudder horn as I guess that will get painted so I’ll just alodine it. Does priming the alodined surfaces give extra protection? Like the HS spar doublers? Thanks again.
 
Prime

Thanks again for the responses. I’ll search for the acid solution in another form. I’ll ring Henkel in nz to see if they have the product. I was given the alodine solution (most of a gallon) so have not dealt with any resellers. I won’t prime the rudder horn as I guess that will get painted so I’ll just alodine it. Does priming the alodined surfaces give extra protection? Like the HS spar doublers? Thanks again.

Yes. I would prime exposed parts and fay surfaces of parts.
 
ideas

Thanks again for the responses. I’ll search for the acid solution in another form. I’ll ring Henkel in nz to see if they have the product. I was given the alodine solution (most of a gallon) so have not dealt with any resellers. I won’t prime the rudder horn as I guess that will get painted so I’ll just alodine it. Does priming the alodined surfaces give extra protection? Like the HS spar doublers? Thanks again.

If priming over alodined surfaces I'm assuming that a non-etching primer should be used, since the alodine conversion is providing the bond to the ali and an etch will be counter-productive because it would etch into the thin layer of alodined protection. An epoxy is probably the way to go.

Phosphoric acid was a common ingredient in household rust converter liquids but I noticed the formulas seem to have recently changed to more benign ingredients...

Some co-builders who used alodine disposed of the waste by mixing it into a concrete block and locking it up that way.
 
If priming over alodined surfaces I'm assuming that a non-etching primer should be used, since the alodine conversion is providing the bond to the ali and an etch will be counter-productive because it would etch into the thin layer of alodined protection. An epoxy is probably the way to go.

Phosphoric acid was a common ingredient in household rust converter liquids but I noticed the formulas seem to have recently changed to more benign ingredients...

Some co-builders who used alodine disposed of the waste by mixing it into a concrete block and locking it up that way.

Correct. The etch is a cleaner and is used to prep the aluminum for the alodine step.

Funny/sad story about self etching primer. Back in the early 70’s Cessna and Piper were using self etching primer. Back then you would buy a gallon of primer and a gallon of acid and mix equally. After spraying, the primer needed to cure out for about three days to let the acid fully evaporate. The bean counters saw this and had a fit. Those planes needed to be painted quickly so they could be sold. The paint shops said ok and started knocking them out. By not letting them fully cure the paint would trap acid in the primer. In a short amount of time corrosion would start to form. They ended up buying a bunch of repaint jobs.
 
Ok guys. I won’t use my self etch primer over any alodine surfaces. I’ll buy a little two pack setup for those parts…..when painted later once the plane is finished will that create an issue for the top coat? I guess a two pack epoxy primer non self etching?
 
Hi I am NOT using alodine for most things as I’m wanting to avoid hexavalent chromium during my build however I have a small amount sealed in a 20 litre pail in its gallon container. I would like to protect my non alclad doublers, horns, brackets etc.

Is it easiest to brush it on or dip it….after doing these parts you have to wash off with water and how do people catch the rinse water to dispose of it properly. Obviously not wanting to really have it anywhere near me and certainly not all over my property. I have rubber gloves, a hazmat suit, respirator etc….want to get all these tail parts done in one go.

I am NOT using akzo zinc chromate. Same deal as above.

I am using wattyl super etch using my own gun with rattle cans for small touch Ups.

I started with Stewart systems ekopoxy but really did not get on well with it. I do have their eko clean which does a great job of de greasing and cleaning the Ali.
Any reason the water based eko clean would be no good for a single pack epoxy primer like super etch? I am not etching with the eko etch I have as the super etch does that itself…..after scotchbrite and cleaning.

Not looking for a primer war here….just choosing not to go near the really poisonous stuff for personal reasons any more than I have to….just asking the basic questions above.cheers.

If you want to avoid Alodine, then etch it with alumiprep or equivalent and coat it with a primer after you rinse it with water. Any primer should do because it blocks air from further oxidizing the surface. When I first started, I was using the rattle can self-etching primer. Then I switched to using 2-part epoxy primer. I don't see any difference after 4 years of the parts getting exposed to the air inside my garage with huge swing in temperature and humidity. I've seen the bare alclad exposed to outside air without much effect other than losing its shine.
Personally, I alodine everything and I found that I could prime the surface years afterward with a simple wipe down of denature alcohol. I am convinced all of these primer chemicals are immune from builder mistakes. They will stick to almost anything, maybe except for oily surface.
 
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