K

kaye7877

Member
I Alumiprep 33'ed and Alodine 1201'ed my wing ribs and rear spar parts today. The parts came out of the full strength Alodine at about 80 seconds and looked perfect. I was running short of time, so simply placed the pile of ribs in a kiddie pools full of water at ambient temperature (about 65f) for retrieval after dinner. After returning from dinner I began retrievig the parts and noticed that most of the color had gone away. The parts are almost back to silver, but still have a slight bit of color.

Did I Alodine long enough the first time?
Did I remove teh Alodine by leaving them too long in water?
What is the next step? Alodine again? Paint?
Did I just remove the color?

I'M CONFUSED!!
 
Brad,
Could you email me some photos of the before and after (or at least the after)?
So long as there is still some gold color, you should be OK. 80 seconds is a bit on the short side, time wise. 3 minutes is what I usually use for 2024-T3. 6061-T6 will take 2-4 times longer.
You only need to dip the parts in the rinse water for a few minutes. That said, I have also left parts in a lot longer. The length of time in the rinse water never seemed to affect the color much. Be aware that it's normal for the color to lighten up when it's rinsed.
FYI, do not touch the parts till the rinse water has dried, or the handling will also rub off some of the Alodine protection. Once the rinse water has dried, you can not 'darken" or improve the Alodine by simply dropping it back into the Alodine bath. The Alodine layer now in place will prevent that. You would have to re-immerse the part(s) in the etch solution for a fairly long time to remove the Alodine. This would probably cause the non Alclad edges to turn gray (oxide layer) due to the long exposure to the etch solution. It's probably best to just leave them alone.
Email me photos to be sure.
Charlie Kuss
 
kaye7877 said:
I Alumiprep 33'ed and Alodine 1201'ed my wing ribs and rear spar parts today. The parts came out of the full strength Alodine at about 80 seconds and looked perfect. I was running short of time, so simply placed the pile of ribs in a kiddie pools full of water at ambient temperature (about 65f) for retrieval after dinner. After returning from dinner I began retrievig the parts and noticed that most of the color had gone away. The parts are almost back to silver, but still have a slight bit of color.

Did I Alodine long enough the first time?
Did I remove teh Alodine by leaving them too long in water?
What is the next step? Alodine again? Paint?
Did I just remove the color?

I'M CONFUSED!!
Click to expand...

Heck I have to give you props for still doing the Alodine during the wing build! I gave up on it with the HS!! Made a huge mess in the garage! :(
 
Any color change

To echo Charlie's comments, any color change is an indication there is a protective layer of converted Al and that the Alodining process was successful. It does not need to look like a gold-anodized spar or anything. Furthermore, the color change need not be 100% uniform. It may appear a bit splotchy, so long as it has a dull, gold-ish tint, you're good to go.

Remember, don't let the Alodine dry before rinsing. (If it does, re-wet with Alodine before rinsing.)

I normally rinse and hang to dry immediately. At worst, I do small batches of 3-5 parts at once, if they're small. I did big parts on warm, humid days, one at a time to keep it from drying.

Also, be sure to thoroughly rinse the Alumi-Prep off before applying or dipping in the Alodine. And it's best to minimize the time between Prep rinse and alodine, to prevent the AL from oxidizing on it's on before Alodine.
 
Thanks for the info! The parts are a uniform very light golden brown.

I etched, then the well rinsed parts were submerging in a kiddie pool until being submerged into the Alodine bath.

I think I'll just paint them.
 
I want to re-iterate Bart's recommendation of minimal time between rinsing off the etch and dropping the part into the Alodine (or Iridite, DoradoKote, etc).
I've found the instructions on some brands of etch, recommend letting the etched and rinsed part dry prior to dipping in the Alodine. DO NOT DO THIS! As soon as the etched part dries, it will start to oxidize. This oxidation will prevent the Alodine from taking hold.
Rinse (submerging in water is best) the etched part for a minimum (there is no maximum so long as the part is totally submerged in rinse water) of 2 minutes. Remove the part from the rinse water bath and immediately submerge it in the Alodine solution.
Charlie Kuss
 
Color fade

I recall reading recently that placing Alodined parts in warm (hot) water right after treating would 'bleach' some of the gold color but does not affect the conversion coating. Just wish I could remember where....CRS strikes again.

Dave
 
Have worked in the aircraft industry for years, and as long as you could see any color we called it good and applied the primer. To echo one of the other comments give them a quick rinse and let them dry before handling or you will damage the film. Make sure there isn't any powdery residue after the rinse and dry.
 
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