[pilot28906]

What do most use as primmer on the wing main spar countersinks; rattle can primer, alodine pen, etc? I am using Sherwin Williams two part on other surfaces and rattle can NAPA for spall parts.

Thanks

 

[mikehoover]

I just used some leftover primer from a priming session and dabbed each countersunk rivet hole on the main spars with a Q-tip.

 

[WenEng]

Ditto on the Q tip...

Sprayed rattle can etch primer onto qtip and coated the exposed aluminum countersink. Tried just spraying the hole but that was too messy. Couple dabs with a saturated Qtip did the trick.

 

[bkthomps]

I plan to countersink through painters tape, hoping this will work fine

 

[airguy]

I plan to countersink through painters tape, hoping this will work fine

Make sure you adjust your counterskink cage to account for the thickness of the tape - I suggest punching a few holes in scrap first.

 

[Flying Scotsman]

Alodine. The c-sinks are small enough that dabbing on alodine with a small "acid brush", it will form a meniscus due to surface tension. Let it sit for a few minutes, then wipe down with a wet paper towel and blow it dry.

Came out looking like perfect next to the anodizing on the spar.