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Old 09-03-2012, 10:19 AM
rwagner24 rwagner24 is offline
Join Date: Aug 2011
Location: Jonestown Pa
Posts: 68
Default First Alodine Experience Bad

Hey guys,
I am building a RV8 quickbuild that sat in a hangar in Pa for about 8 years. The surfaces of the wings and fuse have light white corrosion. I just finished the tail so It will still be awhile before I get to the priming stage of the wings. I wanted to do somthing to clean them up and protect them in the mean time. I have had many suggestions from polish, alodine, prime and just wash with dawn and build on. I talked with a corrosion guy at osh this year that said to alodine them so this weekend I tried and the came out bad. Here is what I did and the pics show what I got.
1 Washed well with a warm water/dawn solution towl dried.
2 Washed with Aluma Prep mixed 1:3 with water let on 3 mins rinsed
3 Found some spots that didnt come off and ended up scotchbriting the whole wing. ReAluma Preped and rinsed. Made sure water didnt bead up.
4 Let dry completely overnight in garage.
5 Wiped down with full streangth Alodine let sit 3 mins rinse.

The thing looks like some tie die shirt from the 60's I Re did the aluma prep wash and alodine and it looks pretty much the same. I'm thinking let it alone till primer. I have the other wing and fuse to do though. Any suggestions?

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Old 09-03-2012, 12:41 PM
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Pat Hatch Pat Hatch is offline
Join Date: Jun 2006
Location: Vero Beach, FL
Posts: 871

They look pretty normal to me... that's about what you would expect. Cosmetically they ain't pretty until you get the first coat of primer on them. I would do the same to your remaining parts: wash with Dawn, aluma prep (muriatic acid), alodine. If you want a little more consistent look, leave the alodine on a little longer. You can experiment with some scrap, but the older the alodine is, the longer you want to leave it on. It loses its strength over time or if you use the same batch more than once.

You could also give everything a light coat of primer for more protection.
Pat Hatch
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Old 09-03-2012, 12:49 PM
scsmith scsmith is offline
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Location: Ashland, OR
Posts: 2,423
Default no worries

The blotchyness is partly from spots you scotchbrighted more aggressively, and partly from places where the alodine went on fresher or stayed longer. Try leaving it on longer to build a thicker passivation layer, and perhaps a bit more consistent look.

But really, no one cares what it looks like at this stage, just good protection
Steve Smith
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Old 09-03-2012, 02:15 PM
sstellarv10 sstellarv10 is offline
Join Date: Feb 2009
Location: Southbridge,MA
Posts: 193

I found that the parts that were too large to soak, like the skins came out blotchy. It was just caused by the inconsistant layer of alodine that you could keep on the surface at any given time, no worries.
Steve Stella
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Old 09-03-2012, 02:32 PM
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Buggsy2 Buggsy2 is offline
Join Date: Jul 2008
Location: NorCal
Posts: 565

I like to include a more aggressive solvent in the cleaning steps. I like 100% isopropyl alcohol I get at Frys (an electronic chain store), but MEK or acetone should work too. And rinse with distilled water, and/or at blow dry with shop air, just before the alodine.
Ralph Finch
Davis, CA
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Old 09-03-2012, 03:15 PM
rwagner24 rwagner24 is offline
Join Date: Aug 2011
Location: Jonestown Pa
Posts: 68

Ok thanks guys just thought it would have a more even coat. I guess there is more protection there than there was before. I will try wiping with mek or alcohol on the next wing. Not gonna worry about it anymore it will be primed with epoxy later and never seen again.
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Old 09-03-2012, 04:02 PM
FL370 FL370 is offline
Join Date: Aug 2012
Location: S Florida
Posts: 12

Also be careful handling the freshly alodined parts as the new coating is VERY soft and takes about 24 hours to harden. My tail skins came out blotchy but all the other parts that could be soaked came out nice. Remember to keep the surface wet the entire time and do not allow alodine to dry on the surface. Rinse gently and then allow to air dry.
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Old 09-03-2012, 05:30 PM
rwagner24 rwagner24 is offline
Join Date: Aug 2011
Location: Jonestown Pa
Posts: 68

Ok then maybe not rinse with a pressure washer then either
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Old 09-03-2012, 06:10 PM
chaskuss chaskuss is offline
Join Date: Mar 2005
Location: SE Florida
Posts: 1,497
Default The etch instructions lie to you.

Do NOT let the rinse water from washing off the etch acid dry before applying the Alodine. With old, corroded aluminum, letting the rinse water dry simply allows the corrosion to reform. Alodine will ONLY take on CLEAN aluminum. This is one process that absolutely requires cleanliness. Apply the Alodine while the rinse water from the etch acid is still damp.
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Old 09-04-2012, 11:19 AM
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Rick6a Rick6a is offline
Join Date: Jan 2005
Location: Lake St. Louis, MO.
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Default Details

As others have said, the alodine is completely normal. That said, I too am a bit turned off by the splotchy look. It is strictly a temporary cosmetic thing that doesn't mean much in the overall scheme of things. That said, to separate myself from the pack in the production environment where 99 guys out of a 100 were perfectly happy to "settle," here's what I did to achieve a more uniform looking coating. I would first lightly moisten with water (strictly speaking it should be deionized water but who cares ) a piece of cheesecloth then soak the cheesecloth in alodine. Next, I would uniformly wipe the subject surface down with that alodine soaked cheesecloth and let it set briefly before rewiping the surface with pure water. That technique went a long way towards achieving a more uniform golden color. I used often used that same technique when building my RV's with similar pleasing results.
Rick Galati
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