Epoxy primer inside spars

[David47]

You did alumiprep first then alodine and that was all? No primer?

Thanks all for the replies.

Scott

Yep, that was it. If you look up the properties of alodine you'll find that it has corrosion inhibiting properties as well as acting as a surface preparation prior to painting. It's the chromium content in the alodine that does the trick. The gold standard for corrosion protection in severe environments would be alumiprep (or similar), alodine and then epoxy primer (2 part). What bbs428 has done will have a similar effect - the vinegar will help reduce some/most of the oxidation layer. Alodine 1200/1201 is a pretty good inhibitor, and it'll also maintain your electrical conductivity. I decided to go this way because it's way simpler than priming. As bbs428 says, you can slosh and wash (water rinse) .... and you'll have good protection .....

[FoxTrotter]

Are you guys doing this spar prep on quick-build wings (which is what I have)? Not clear to me how you're "holding the spar over your head and sloshing" with an assembled quick-build wing, nor how you're treating the exterior of the spars with all the ribs etc already in place.
Thanks - Michael

[efwd]

Youll need to either spray or apply with a brush when it comes to the exterior surfaces. As for the slosh, I propped the quick built wing on a sawhorse. I put tennis balls into the spars at the floor. I poured the primer in at the end propped up on the sawhorse. quickly put the tennis balls into the ends and ran to the other end, picked it up and tilted back and forth. I used new, fuzzy tennis balls. Leaked pretty good. I think some have stopped the leaks by putting saran wrap over the ball first.

[airlina]

with finished wings on saw horses,plug the spar ends with afformentioned tennis balls , dump epoxy primer into open ends and plug with two more tennis balls, then lift one end at a time with the other end on the saw horse and slosh. go to the other end of wing and do this again. flip the wing over and repeat, inside done and can be done solo. for my exterior spar protection, i used a small hobby type spray gun and shot epoxy primer to the spars around all the wood parts. used the same rig to varnish all the wood parts at a later time. the small hobby type gun can be used in tight quarters ,accurately with little overspray. Bruce N199CL

[FoxTrotter]

Thanks, guys. Did you go straight to the epoxy primer, or was there some kind of preceding prep, eg Alodine or equivalent?

[efwd]

Alcohol cleaned, whiped down with scotch brite ( no circumferential rubbing ), alcohol cleaned again then straight to spraying Primer as the previous post describes.

[FoxTrotter]

Dustin, I used Corrosion-X inside my spars. Living in the low humidity of Colorado, I'm thinking that is sufficient although I will probably renew it at each condition inspection. I also soaked the inside of my lift struts with linseed oil early on.

Colospace, how did you spray the inside of the spars? Did you simply use a spray can, spraying at one end and letting it drain to the other end, or did you use some kind of special long wand? How many ounces did it take to convincingly cover the entire internal length?
Thanks
Michael

[efwd]

Ken added a Pic of his spray gun he used back on page 10 of the Builder hints and tips thread. I think post #123

[colospace]

Michael, I did it while the wings were folded. Wings pretty level, but tips slightly low. I put tape over the outboard ends of the spars and just sprayed liberally from the inboard ends. The stuff is supposed to diffuse in the air and coat all the surfaces in a volume. I left them closed up and noticed a couple of weeks later that excess was dripping out the ends past the tape that was by then a little loose. Don't know how much I used, but the can still feels pretty full.

[FoxTrotter]

You did both wings with one 16-oz can of CorrosionX? Did you use the standard, the HD, or the aerospace?

Did you epoxy primer the outsides of the spars?

Thanks
Michael