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Old 12-29-2010, 08:21 PM
gwit gwit is offline
Join Date: Aug 2010
Location: Logandale, Nevada
Posts: 4
Default prep work to prime

I have just purchased the empenage of my RV 8 and am very excited to start my new project and dream. I am having many reservations about this whole priming stuff and have decided to just prime the parts where they mate with a spray can primer. I have not made a final decision on what to use but was wanting to inquire as to the process of preparation in using Zinc Chromate and also an acid etching primer like Sherwin Williams 988 or Marhyde. Can anyone help me as I am very unfamiliar with any of the paint primer preperation processes. Again I am concerned about weight so I don't want to prime the entire pieces. I was afraid that if I use the alodine that it would strip the protective coating off the metal. Any thoughts will help me in this decision.

Thanks, Greg
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Old 12-29-2010, 08:53 PM
Sig600 Sig600 is offline
Join Date: Nov 2005
Location: KRTS
Posts: 1,798

I was spending the cash on zinc for a long time, and driving an hour out of my way to pick it up. This forum convinced me to just go with rust-o or duplicolor self etching primer. 1/3 of the cost, and I can pick it up down the street.

That said, I've talked to a lot of people that have said some of the major manufacturers never primed anything. Buddy of mine opened up the empennage on his 40 year old C-180 and it was bare metal, with only slight traces of white surface corrosion. He reskinned everything, and rattle can primed it.
Next?, TBD
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Old 12-29-2010, 09:17 PM
KatieB's Avatar
KatieB KatieB is offline
Join Date: Jun 2010
Location: Belton, MO
Posts: 1,127
Default One Theory

We've used PPG SXA 1031 self etching rattle-can primer for all interior parts on several RV projects in the last 2 years. It's sort of expensive ($12/can i think) but really easy to use. After the parts are deburred and ready to rivet, I clean them with Naptha, then buff them with a Scotch-Brite pad, then clean them again (wearing latex gloves). Prime as soon as the naptha dries with the spray cans. The primer dries in just a few minutes at cool room temperature.

You'll read a lot of theories about priming, but this way we won't have to worry about it, and full coverage does make the inside look finished.
Katie Bosman
EAA Homebuilt Advisory Council
Rebuilt most of SNF tornado victim RV-3B Tony Boy II (had to sell him, but he's flying!)
RV-9 93281 tail kit has arrived... here I go again!
VAF Dues Paid 2021!

Last edited by KatieB : 12-29-2010 at 09:23 PM.
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Old 12-29-2010, 11:13 PM
RV7AJeremy's Avatar
RV7AJeremy RV7AJeremy is offline
Join Date: Aug 2010
Location: Gilbert AZ
Posts: 416
Default Zinc Chromate

Do some research on the health hazards of Zinc Chromate, that's what turned me off to it. I am new to this also so I can't provide much experience. I use the dupli-color self etching primer and have been really happy with it so far but I am only in my third day of building. Good luck
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Old 12-30-2010, 07:15 PM
terrye terrye is offline
Join Date: Feb 2010
Location: Vancouver, BC, Canada
Posts: 932
Default Prime

Ahh the primer wars! Do a search on this site and you will find lots on the never ending battle.

FWIW I am just starting the fuselage on my RV-9A and I decided in the beginning to fully prime all interior surfaces. Per the paint manufacturer I used Alumiprep (to clean the surface) and Alodine (to increase the corrosion resistance of the surface. No you won't dissolve the surface, only needs 5-10 minutes in the bath). Then primered with PPG Super Korapon epoxy primer. This stuff is "fluid resistant" which means everything used on airplanes including Skydrol (which we don't use). I didn't like the idea of brake fluid or some such dissolving the primer if accidentally dropped on it.

I also have a 1966 Cessna 150 which I used Dinitrol anti corrosion spray about 15 years ago. There was some minor evidence of corrosion prior to this application. It's been fine ever since. Only drawback is it's still a bit tacky if you're working inside and leaning on the inside skin surface.

The main reason I am primering the RV-9A and Dinitroled the C-150 is weather here. We are near the coast of the Pacific Ocean and it does rain here a fair amount.

Long way of saying, build it for your conditions. If you live in a dry climate with low humidity you can probably skip primering all of the alclad (but do primer the non alclad parts such as extrusions). If you are in a wet climate consider a good epoxy primer during building or Dinitrol after the aircraft is finished.
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Old 12-31-2010, 08:08 AM is offline
Join Date: Feb 2009
Location: Netherlands
Posts: 33

Hi Greg,

I switched to rattle cans early in the build process. They are easy to work with and allow for easy spot priming when needed.
I use RustOleum Hammered paint. Just use alcohol to clean the aluminium and let it dry for a few minutes, warm up the aluminium and the rattle can and spray if it is cold in your workshop - no scotch-brite needed.
The Hammered paint is touch dry in one day, but needs one week to fully harden. When hardened, it is almost impossible to remove
Make sure you paint large surfaces horizontally and spray in overlapping directions (criss cross so to say), this creates a nice glossy finish.

Good luck,
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Old 12-31-2010, 09:25 AM
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Doug Lewis Doug Lewis is offline
Join Date: Jan 2010
Location: MN
Posts: 195

NAPA 7220 self etching rattle cans are still on sale through today at half price. ($5) Picked up a case yesterday.
RV-8 Wings almost done
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Old 01-11-2011, 06:49 AM
Funbobby Funbobby is offline
Join Date: May 2010
Location: Vermont
Posts: 13
Default Primer Wars!!!

I'm a new builder and was totally overwhelmed with the primer issue as well. My journey has taken me to the website of a builder who uses SEM self etching primer (I can't remember the guy's name, but he's supposedly a very experienced RV builder). He recommends Coleman fuel as a degreaser, because it's cheap and it works - so far so good.

I recently spoke with a professional automotive painter who said that the self etching primer is great, but that I still would need to top coat it with a high build primer or top coat of paint if I wanted protection. My current thinking is to put a VERY THIN coat of self etching primer on and then a VERY THIN coat of high build primer for protection. I'm trying to balance the ideas of protection vs. keeping the plane light and all though I want a very light aircraft, I also will be spending many hours and many years building it and I want it to last/have good resale value. Any thoughts on this?

I have read about very efficient builders priming all parts needing primer as soon as they have inventoried their kits. This saves a lot of time and is what I intend to do with my wing and fuse kits. I'm open to thoughts on this as well, including any strategies!!!

Finally, the automotive paint guy referred me to his supplier for further information and the supplier told me that SEM self etch top coated with SV High build primer will be ok on the outside of the plane as well and that ANY top coat will be compatible with the primer. I've always heard that you need to use compatible paint products. Who do I believe?

Finally, I'm thinking that I should wait to prime the exterior of the skins, because I think I read that if you don't top coat within X amount of hours you will need to sand. I'm soooo confused! Any opinions?

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Old 01-11-2011, 08:52 AM
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JonJay JonJay is offline
Join Date: Jan 2007
Location: Battleground
Posts: 4,348
Default Boil it down to something simple...

No reason for a war, it is only a decision that you need to make in regard to the level of protection you feel you need.

First level;
Alclad in itself has a level of protection in the pure aluminum coating. Thousands of spam cans out there with thousands of hours with this protection only. No added weight and no investment in time.

Second level;
Self etch/Wash primer only. Vans "unofficial" test showed that SW Wash Primer provided a decent level of protection over nothing, that is why their QB kits have this level of protection. This is good enough for the bulk of the QB fleet. I know of few that take this further and topcoat the internals of their QB's. Very little added weight and a simple prep and application process.
I put the "rattle can" products in this category but most just use them on the seams and I have no opinion on what level of protectiont that provides to the overall airframe.

Third level;
Etch and Epoxy Prime/Top Coat. Some primers seal, some dont, if they dont you should top coat. This is the best level of protection. It does take time and adds some weight.

CorrosionX, and other treatments;
I do not have experience with the products but those that do swear by them. I believe it is part of an on going program, not a one time cure.

Zinc Chromate; ( this might be over simplified)
Zinc Chromate is a toxin to organic material, hence it is a corrosion deterrent and it also provides protection by sacrificing itself as it is more active in electrolysis than the base metal. It is common to see the coating corrode but the metal beneath stays protected. However, at some point, too much of the Zinc Chromate is sacrificed and corrosion will set in the base metal. It is far less popular these days so I left it off the list but I would put it from my experience in the second level of protection.
I am not aware of any "sacrificial" modern coatings.

Once you decide what level of protection you think you need, then it is all about specific products, systems, and application. None of the products work well if you do not follow the correct prep and application instructions.

I hope this helps folks trying to make what should be a simple decision a little easier.
Smart People do Stupid things all the time. I know, I've seen me do'em.

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Old 01-11-2011, 12:15 PM
Funbobby Funbobby is offline
Join Date: May 2010
Location: Vermont
Posts: 13
Default Thanks

Thanks for the input - very helpful. No offense on the "primer wars", just chuckling at the term!

~Bob Baker
RV-8 Newbie!
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