K

kyle Lee

Member
Hi all. I'm a new builder and was hoping to get some insight from those who have primed their RV-12. I guess the main question is any regrets with the finished product and weight? I am only working my way through the empennage kit. I have decided to prime everything since I live right on the coast that faces the chilly Southern Ocean in Australia. I started with some nasty lead based BMS 10-11 on the horizontal stabiliser and the spars of the vertical stabiliser. Looks great but I was concerned about weight and switched to cans of Zinc Phosphate. I am halfway through priming the skins of the tailcone and am up to can #6. Each can is 340 grams (12 oz for my American colleagues). I don't believe I am being too heavy handed with the primer but I think this is going to add up. I have considered just priming around the rivet holes of the skins to lighten things up in the future. Any thoughts?

Kyle Lee
 
Primer

Kyle,

I'm over in the West, not far from the warm Indian Ocean. I've used grey Wattyl Super-Etch in 400 gram spray cans for all my priming. It's an `industrial' grade primer (whatever that means), but it seems to have a good reputation.

Started off priming just the contact surfaces and ribs and spars on the fin, rudder, stabilator and tail cone, but then decided to prime all the interior of the wings and the fuselage (currently half finished). I'm guessing I've used around 50-60 cans so far in the 16 months since I started building (didn't track it too closely), but another few cans should be enough to finish the job. Spray cans are not a cheap way to buy primer, but they are very convenient, and the paint goes on easily.

If I was starting again, I would also have fully primed the interior skins of the fin, rudder, stabilator and AS tab - all those parts that are difficult to get to later. The tail cone is more accessible and easy to inspect, so I'm not sure if I would do any more than the contact surfaces.

I also bought a litre can of the same primer and have primed and set all the `pop' rivets while wet. Maybe over-kill, but it's easy to do, and will help to seal the rivet holes.

I'm not too concerned about the weight of the primer. Dry film thickness is 20 microns, wet is 200 microns. The solids content of the cans is 10% by volume, which will probably work out at around 10-12 lbs total by the time I've finished (assuming a solids sg of about 2.0-2.5).
 
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primer

hi kyle I alodined everything that I could and then two packed primed all the internal surfaces of the wings stabilator rudder etc I etch primed all the skins how is the building going I just clocked over 120 hours in ours
 
RGMWA,

I think you are using a good product as I was pointed towards Wattyl Super-Etch as an option. Apparantly the etching quality makes it stick well. You are right about the convenience (and price) of cans. Unfortunately, I find that it "spits" at times. Know any tricks to prevent this?
Good to know that you are at about 50-60 cans. I guess that will help in my approximations. How do you calculate total dry can weight of primer? (excuse my ignorance please). The specific gravity of the primer I am using is between 0.77-0.85 while the solids content of the can is 16.3%. I don't suppose it will be too different from what you are using and by your calculations, isn't very heavy.
I too primed everything on the inaccessible "tail feathers" and am having thoughts about just priming the contact surfaces of the tailcone skins. I thought that I would prime the skeleton of the wings but just the contact surfaces of the wing skins.

Thanks for your reply.

Kyle
 
Crashley,

Good to hear from you and that you are getting a bit of flying in.

Yes, I am alodining all the small parts as well. I started out with two packed primer and will probably use it for the rear wing spars as well. It does a really nice job but looks thick and heavy.

The building is going well. Really enjoying the journey and the learning. The only thing is that it reinforces how little time I have in my life. No matter. Its not a race.

Happy flying.

Kyle
 
Super-etch

Kyle,

It's an etch primer, but you still have to scotchbrite the surface to get a good bond. I've also had the spray`spit' occasionally, but think it's because I was holding my rubber-gloved finger a bit too far over the nozzle, and slightly into the spray zone. That's my theory anyway. Obviously you need to give the can a good one to two minute shake as well, particularly if the weather is cool.

I'm not sure about my weight calculation because I don't know what's in the can, except that the solids content is 10% by volume, and the total weight of the contents is 400gm. I'm guessing that 10% by volume may translate to 20%-25% by weight, or around 80-100gm. It's only an estimate though. Whatever it is, I don't think the extra weight will keep me on the ground ;)

I looked at using Alodine initially. The main reason I didn't was that I didn't know how to get rid of the waste afterwards. It looks like pretty toxic stuff, (although so is the epoxy primer).
 
Kyle, Im East Coast of Australia as well being Geelong.

I'm using an Etch spray as well. As the surface on the plane is already treated I'm spraying all contacting surfaces but thats about all. I also spray the underside (non visible side) of rivets.

My theory is that the plane is easy enough to view at regular intervals for any developing corrosion to which I do not expect any.

Is you do a search in the advanced area under RV12 prime you will get several post discussing this topic.

Regards,

Jim.
 
I am using SEM Self-Etching Primer on portions of my RV-12 with good results -- it's quick, easy, and appears to be adhereing well to the roughed-up and Alum-Prep'ed skin. There are other similar primers out there as well.

When using spray cans, I always hate to clean the spray nozzle by inverting the can and wasting precious propellant -- I'm cheap that way. Instead, when done spraying, I remove the nozzle and give it a blow through with air (if you're a whimp, your breath through a tube will do, or be a real man and ..."just put your lips together and blow"...;)), wipe any paint off the nozzle, and then store the can inverted. This position seems to keep the paint ready to go with the next use. If I store the can in an upright position, it takes several seconds of wasted propellant for the paint to start spraying out.

...I've got to get a life ....
 
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