[TroyBranch]

Just want to get some opinions on etching and priming both side of the skins prior to assembly. I have always only primed the inside components. I have used Stewart Systems on many projects and the primer sprays really nice. My thought was if I am planning to paint the aircraft myself, maybe this is a good idea. This will be on the 15 so the pulled rivets will be another step.

The primer will likely get marked up a bit so it will need sanding and likely a second coat in areas before top coat. The rivets could be scuffed and etched, rinsed then primed. Not sure of this less or more work in the end as I still have to prime all the rivets but so much less work to etch at that stage.

The only thing I see as an advantage is I don't have to wash an entire wing down with water after etching.

Anyone try something similar?

 

[PaulvS]

Just want to get some opinions on etching and priming both side of the skins prior to assembly. I have always only primed the inside components. I have used Stewart Systems on many projects and the primer sprays really nice. My thought was if I am planning to paint the aircraft myself, maybe this is a good idea. This will be on the 15 so the pulled rivets will be another step.

The primer will likely get marked up a bit so it will need sanding and likely a second coat in areas before top coat. The rivets could be scuffed and etched, rinsed then primed. Not sure of this less or more work in the end as I still have to prime all the rivets but so much less work to etch at that stage.

The only thing I see as an advantage is I don't have to wash an entire wing down with water after etching.

Anyone try something similar?

I sort of did something similar and primed the outside skins by spraying a stripe along each row of rivets so as to protect the skin under the rivet heads. This was using a zinc chromate self-etching primer.
When the time came to paint the exterior finish coats I used an epoxy primer that was not compatible with the etch primer that I sprayed during construction (the etch primer is now no longer available), so it needed to be all stripped off, which took about a week to do.

 

[Kyle Boatright]

I wouldn’t prime the exterior until time to paint. It’ll collect oil from your shop and your hands and tons of dirt, so you’d probably need to deep clean it and apply a second layer of primer before paint.

 

[Ben Ellis]

My personal opinion is I wouldn't do it. The top two reasons that come to mind is that the primer you spray is going to get messed up while you work on the plane. That likely means more work cleaning up and leveling the primer to get a smooth base for the paint. The other reason is that you may decide to go with a different paint system for the outside, and in that case you'll need to spend a lot of time striping and cleaning off all of the old primer.

 

[Nashpdman]

I'm priming both sides of mine. I'm using Akzo-Noble, stuff is pretty much bullet proof! Mine is QB fuse & wings so only got to prime the tail. I will be the painter so no issues there. Does it get dirty, yes, but that won't be an issue. I expect to 3M scuff and shoot a dust coat of Akzo before finish primer, then paint. The Akzo goes on really light and easy.

 

[JonJay]

Many paint systems recommend a certain time from prime to top coat for a proper chemical bond for best adhesion.
Check your product specs and instructions.

 

[wirejock]

Many paint systems recommend a certain time from prime to top coat for a proper chemical bond for best adhesion.
Check your product specs and instructions.

Yes. If primer is cured, the only bond is mechanical by scuffing the primer.

 

[jackking123]

Just want to get some opinions on etching and priming both side of the skins prior to assembly. I have always only primed the inside components. I have used Stewart Systems on many projects and the primer sprays really nice. My thought was if I am planning to paint the aircraft myself, maybe this is a good idea. This will be on the 15 so the pulled rivets will be another step.

The primer will likely get marked up a bit so it will need sanding and likely a second coat in areas before top coat. The rivets could be scuffed and etched, rinsed then primed. Not sure of this less or more work in the end as I still have to prime all the rivets but so much less work to etch at that stage.

The only thing I see as an advantage is I don't have to wash an entire wing down with water after etching.

Anyone try something similar?

This subject has been beat to death for decades... ANS: Up to you. The clad aluminum is corrosion resistant. The primer will improve corrosion resistance. Down side, time prepping (significant), cost of materials and weight. If you are not going to flying near salt water, hanger queen the plane will out live you.

There are un primed 30 and +40 yr old RV-6's and RV-3's and RV=4's, structurally sound with no corrosion. Many Cessna and Pipers as well not primed internally and some of these are over 60 to 70 yrs old.

I did prime the the rib flanges of wing ribs and strip of wing skin where they mate. I primed the rear spar. Of course any extrusion must be primed. CLAD aluminum can be left alone, but up to you.

 

[fixnflyguy]

Prime inside, don't prime outside until ready to paint..let the painter do the outside. He will curse you for priming the outside, and it may lessen his warranty. I was my builder, primer and painter , and I used all Akzo for my priming up to the external. I used PPG Desothane and relevant primers for my paint job. For skins, I suggest and promote rolling it on (inner surface), and that's what we do on the big jet maintenance where I make my living. Smooth foam roller and slight overthinning is perfect for thin inside surface coat, and will look sprayed after it dries.