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first timer, ready to start priming

bruceh

bruceh

Well Known Member
I'm almost ready to do my first priming session on the HS.
I've decided to go the Alumiprep/Alodine/AKZO epoxy primer route.

A couple of questions:
1) Should I prime the interior skins or leave them naked aluminum? I'm sure the Alclad alone would be fine. Any real benefits here? Formed, bent and extruded parts will definitely get the whole treatment.

2) And if I do prime the interior skins should this be done before dimpling the skins? Will banging away with a C-frame to dimple the skins mess up the primer coating?

3) What is a reasonable amount of primer to prepare to do the HS parts? I don't want to waste this stuff!

Thanks!
 
I just went through this myself and will tell you what I did.

I primed the interior skins, I lost alclad in the deburing proccess and it makes me feel good about an area I will never see again.

Prime after dimpling if you choose to prime.

I used about 12 fl oz (355 ml) as I look down at my beer.:)
 
Hi Bruce,

I started off priming all of the inside surfaces including the skin, but as the building went on it became obvious that the wing skins were just too large to do a good job with the alodine. I ended up using the akzo on about 90% of the interior parts. Whatever you decide, I waited until the parts were ready to assemble (all dimpling and deburing completed) and then did the priming. If I had to do it again I would probably prime everything except for the skins. Inland SoCal doesn't present much of a corrosion problem and as long as you don't scratch the alclad too deeply there should not be any problem for a good number of years. As for how much to mix, I made enough to fill the cheep Harbor Freight priming gun cups twice. That should be enough to do all the Hor Stab ribs and the skins. Remember that you only need a thin coating of this stuff. I only used slightly over 1 kit (2gal) for the entire aircraft.

Good luck
Bill
 
Primer Tips

Like the discussions on tip-up vs. slider, and nose-dragger vs. tail dragger, this is one of those subjects. Van's will tell you straight up that priming is not necessary, but that most people do it in one manner or another. If you search the forum, you'll find a whole lot of info on primers and a whole lot of opinions.

Without choosing a side, just make sure you know the pros and cons of whatever system you're going with. Some primers are only designed for paint adhesion but offer no corrosion resistance by themselves. Some primers offer corrosion resistance, but aren't supposed to be top coated. I've read on some builder's sites that the latter is the case with the AKZO, and they had to strip/sand off the primer in the cockpit area before they painted those areas later on. I'm no guru on this and I may be off base, but a little due diligence on your part before you get too deep into it may be in order.

And like the others are saying, any primer has to go on thin. Personally, I've primed the ribs and bulkheads, but not the Alclad parts. That's worked well for other builders here along the humid Gulf Coast, so I just copied that. Also, I haven't had any problems dimpling after priming. The primer is so thin and so tough that it doesn't chip off, regardless if it's a hammer dimple or a squeezer dimple. The advantage to this is that you don't have the "cheese grater" effect of the dimples on your fingers when you're scuffing and cleaning prior to priming.

Everybody has their own methods and procedures, and I'm not sure any two RV's have been done exactly the same. Whatever you go with will probably work just fine. Just make sure you know the applications and limitations of your system--and most of all, wear the appropriate protective equipment called out for in the spec sheets.
 
FWIW,

I prime with akzo too. Prime before dimpling because it was hard to scuff over the dimples; prime before match drilling because it seemed I was having to re-drill due to the primer in the hole and the rivet was too tight; prime after smoothing edges and shaping; removed the blue from the outside of the skin after priming to reduce scratches and keep alumiprep/alodine off the outside. Akzo is tough stuff, the only thing ice found to remove it after its cured is abrasive media. Just another viewpoint. Jim
 
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