Any reason not to prime inside and outside of skins at the same time?

[wirejock]

If I build another, I'll look for a company that will alodine. I'll take all the blue vinyl off and have the whole thing alodined. Zero weight gain. Probably cost way too much though.

[Desert Rat]

R&B Aircraft Painting in Topeka KS advertises that part of their process is an acid etch and allover alodine treatment before primer.

No idea what it costs since that's still several years down the road for me, but there's a picture of an RV on the "process" page of their website where they mention it.

[fixnflyguy]

Alodine is about as easy as it gets, but really its primary function is a conversion coating for better topcoat adhesion. The acid etch process is an alternative to mechanical etch, IE Scotchbrite or similar. Ultimately, the most susceptible parts of our planes are the extrusions not able to take advantage of Alclad which is simply stated a pure aluminum, relatively non-corrosive layer applied to the sheet alloys. Alodine can be applied via cheesecloth/cotton rag wipe on, spray or submersion. Takes only a few minutes, and a good water rinse to be completed. A large plastic bag with a few ounces in it can be used to slosh around small pieces and such. All of my skins were alodined using cheese cloth an rubber gloves..we do it every day in the big jet overhaul world. There are even Alodine marker pens, similar to a big fat dry-erase that you can apply it with and no rinse is required. The skin edges, holes, and any extruded parts are the most important area of primer application while building if you want protection for eternity..that's where the corrosion will start.

[RV7ForMe]

I have had corrosion during the build process on "not started" material. Usually it starts like a hairline at the punched wholes.

That is why I have been in the "prime everything" camp. It sucks. I hate priming. It adds years!

I may try to just shoot the outside where things are riveted and leave the rest bare. I dont think it will corrode there. and if it does there is little harm. I can always shoot it from the outside. But I will never be able to get under the rivets unless I spray before assembly.

just my 2 cents.

[fl-mike]

Originally Posted by rocketman1988

You mean it woul add a lot of time..

I primed only the inside of the skins and about every other part. It took tons of time. After some consideration, I can say that if I build again I probably would not prime. Do you want a 75 year aircraft or a 100 year aircraft?

But, at the same time, it is incredibly disheartening to find corrosion on your mint airplane a few years after getting it flying. There is a five year-old bare metal RV in a hangar near me that is COVERED with corrosion. I don't think the owner has seen it in a couple years, but in coastal areas, Alclad is not enough.

As others have said, a paint shop will strip the exterior back to bare metal, so if you are farming the final paint out, any exterior priming is for the build phase only.