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Alodine -- What's The Deal?

aparchment

aparchment

Well Known Member
Hmmmm, not sure I am doing this correctly. After I Alumi-prepped my parts, ahhhh, empennage parts that is, I dried them carefully and then immersed them in an Alodine bath for 5 minutes. I followed the dilution directions carefully. I pulled them out then rinsed them with fresh water and dried them with a towel. It seems to me that I wiped most of the coating off, and what is left is patchy in hue. Did I do something wrong?

Antony
 
The final look of an alodined surface will end up quite uneven looking (splotchy). Still, rather than wipe the water off, I would always blow it dry with an air nozzle because wiping will leave water in the cracks and crevises while blowing off the area will allow you chase the water out from hidden areas.

You're probably OK.
 
treeez

When you put the parts in the alodine, just wait until you get a good color change to the surface. A full 5 min is pretty long. Once the part changes color, it's protected. Also, the alclad parts don't need the alodine bath, they're already protected. Just blow dry instead of wipe.
Mike
 
Even Color

Anthony,

Don't touch the wet surface at any time. Allow the part to air dry. There's no reason you can't achieve even color with proper technique, but different metals (like exposed edges of 2024 vs. pure aluminum clad surface will color differently.

John Siebold
 
There are two types of alodine, invisible and visible. The invisible looks gold when you brush it on but it rinses off clear. The visible alodine stays golden. If you?re using Alumiprep, check the part number. Number 1001 is invisible and 1201 is a visible coating. I understand that the invisible is often used on planes that will be a polished, not painted. I have some old Dupont alodine that is invisible also. I used it to prep a plane for painting many years ago. The paint job didn't peel so I feel it did a good job.

Cameron Smith
RV4 #68
 
alodine techniqe

Bob Collins said:
The instructions on a bottle of Alodine say 1-3 minutes. Why 5 minutes?
Click to expand...

1. clean surface with alumi-prep 33, risen with clean water. do not dry.

2. alodine -place part(s) in alodine bath, allow 1 to 3 mins.alodine is temperture
sensitive hot days short time, cold days longer. Colour should be pale gold,
darker you have gone to far, will leave a powder residue behind, Allow to dry
wash with solvent to remove powder.before primeing.

hope this is of help, more information at henkel they are the manufacture/suppliers of alodine. to the trade.

regards don :cool: :eek:
 
Thanks

Thanks guys for the answers. I am out of the country, hence the delay in responding.

FYI, the method of soaking, then washing then blowing dry worked like a charm. Thanks for the tips.

Also, I am bathing the parts for 5 min. because the product literature that comes with Alodine recommended 3-5 minutes.
 
The chemistry that happens is almost instantaneous, hence the little time given needed before rinsing.

I think the issue about time is that whatever you do, you do NOT want to allow the surface to dry with the chemical on it; it needs to be rinsed while it is still wet with the chemical.

So instead of "rivet on!", we can say instead; "rinse on!"
 
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