Corrosion

[Jerry Folkerts]

After a break, I've started working on the Super Rebel again. Over the last several days, I've been match drilling stringers on the left wing/tank skin. In the process, I noticed the left wing skin has some corrosion on the underside. It looks like someone flicked a wet paintbrush on it -- numerous small speckles on the whole underside.

The kit was shipped in 2000, and I only recently pulled the plastic off. This is the only piece in the tail/wing that I've seen corrosion on. It appears to only be surface discoloration, and not anything deep. Should I simply wipe it down with vinegar and water , rinse, and then use a self-etching primer? I've been using SEM on all internal parts to date.

Thanks,
Jerry Folkerts

[tedwaltman]

I had some raw stock with scale like that on it. I went over it with a roloc pad then primed it.

Ted

[Dale]

Jerry,

Step 1, You need to wipe down the entire area with a cleaner ( I use acetone) to remove all oils and dirt. Otherwise you will just embed the oil and dirt into the material.

Step 2, Depending on how bad the corrosion is (in this case it doesn't sound much more than staining), use a scotchbrite (med grit) pad by hand or on a jitter bug or palm sander. If it is more severe corrosion the use of a roloc disc pad may be more use.

Step 3, Clean the material by wiping down with cleaner (acetone).

Step 4, Acid etch material and then hose off with water.

Step 5, Apply surface conversion coating (I use alodine) then wash/hose off with water.

Now your material is ready for priming.

[Ken]

I'd wipe it with a rag and a few drops of corrosion-x or acf50 and keep building.
Ken

[snowyriver]

I would not use corrosion x on anything I planned on painting. That stuff is great but is difficult to get rid of. That's the short version of the corrosion x story! Craig

[Harish]

I plan to put my Rebel on floats one day and in preparation for that day, I was wondering if it makes sense to cover the entire insides, not just mating surfaces, of the Fin/Rud/Stab/Elev surfaces as well as the aft half of the fuselage.
I will be using the STITS EP-420/EP-430 Epoxy Primer to cover all mating surfaces and would like to use the same for the insides of the entire empannage and the fuselage...could the epoxy be sprayed or does it have to be brushed on?
I would sincerely appreciate your thoughts, experiences and words of wisdom.
Thanks.

[Ken]

Hi Harish

For fresh water I also only used corrosion-x internally for most of the airframe after painting. I might spray the inside of the tail surfaces if doing it again but I really haven't seen any evidence that it is needed. I thinned the primer so far that you could pretty much see through it when I sprayed below the floor, inside the floats, or small pieces. Any attempt to brush it always resulted in a much thicker and heavier coat which is way overkill on 6061 IMO. The metal has to be pretty clean to get away with a really thin coat but then again it's a waste of time anyway if it is not properly cleaned. The similarly cheap Princess Auto gravity fed sprayer worked fine but the one I had was a bleeder style which flowed air whether or not the trigger was pulled which was annoying as it tended to blow dust around. Their cheap little airbrush was also handy for spraying small parts whenever I had a little leftover primer after a rivet session.

Many of us use acetone rather than MEK as it has significantly less adverse health effects.

One other idea in the archives is to wipe on Everbright. I used it on the exterior of my floats and it has held up surprisingly well. Easy to use and lighter but I'm sure it would interfere with the primer on the faying surfaces if used prior to assembly.

Ken

[Harish]

Thank you, Ken, for your suggestions and insights.