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prep work to prime

gwit

I'm New Here
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
 
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.
 
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.
 
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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
 
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.
 
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,
Duncan
 
NAPA 7220 self etching rattle cans are still on sale through today at half price. ($5) Picked up a case yesterday.
 
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?

Thanks!
 
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.
 
Thanks

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

~Bob Baker
RV-8 Newbie!
 
In building my -8 and living in Florida I decided to prime everything and everywhere usiing AKZO epoxy primer (Aircraft Spruce). For the entire project I used 2.5 gals and every interior part part is covered. Probably an overkill.

I will say it easily added to twice the build time for emp and wings where the part count is high. I often had to force myself to do it since I'd have all the parts ready to rivet together but had to wait to prime and allow to dry.

Prep included using scotch brite pads to buff the entire surface, a mild dish detergent to clean, then Alum-prep, then alodine for select parts, then primer. A lot of work! I'd say the worst part is the prep and post spraying clean-up and disposal of Hazmat.

I like to think the resale value is higher because it will be obvious my plane is very well protected.

No primer war required, do what you like and ignore anyone else :)

Ken
 
Yes, it is funny...

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

~Bob Baker
RV-8 Newbie!

The "war" is not about how much protection one or the other method provides but more about why.
If I am Ken in Florida's humid salt air, then I would want the highest level I could build to. If I am in Arizona's dry desert, nothing might be just fine. Of course, airplanes move, get bought and sold, etc...hence the "never ending debate".
 
I like using high quality Akzo epoxy primer for a variety of reasons. Chief among its advantages is its quick tack cure time. You can prime something and in less than an hour, is dry enough to continue assembly work on. Here's another major advantage, something no rattle can primer can equal....24 or so hours later, after Akzo is fully cured you can wipe it down using strong solvents. I almost always use MEK. The most you will do is lighten up its finish a bit. I have never found any rattle can primer capable of enduring a periodic wipe down with solvents, most especially MEK. Another thing I like about Akzo is that later on, sometimes weeks or even months later, you can touch up an area and its finish will blend in with the original application almost perfectly. Now that might not mean much to most builders but Akzo is THE final finish in my cockpits. Take a closer look at my avatar. That's Akzo on the rear bulkhead. To illustrate the point about touching it up later, I commonly did that very "touch up" thing using a small artist brush dipped in Akzo that was left in the film canister after a priming session. I used it to prime the rivet shop heads and you'd never know those rivets were brush coated by hand and sometimes long after the original spray application.

b63fxt.jpg

Using the little touch up primer pistol fitted with a 35mm film canister shown below, I shot the entire -8 fuselage interior, all of it including the large skins. Oftentimes during the assembly process though, priming involved only one or a few small parts at a time. No problem. It is quick and simple to mix a small amount of Akzo. Typically, I mix less than 4 oz. at a time. The key is pouring an equal amount of part A and part B into separate small dixie cups, then mixing both parts together in the larger dixie cup, pouring the mix into a 35 mm film canister, finally shooting it through a small primer pistol. That way, waste (and expense) is kept to a bare minimum.

jregxc.jpg

My idea of surface prep is nothing more than lightly roughing the surface with maroon scotchbrite then washing in mild soapy water, rinse and dry. Larger parts were done in the bathtub. Really large parts were done outside using a bucket of warm soapy water and rinsed with a garden hose. I do not use Alumiprep at all and only use alodine on steel and non-alclad parts. Just prior to applying Akzo, I routinely give the surface a final wipe down with MEK which as you may know evaporates almost immediately. Clean up is about as simple as it gets. You throw the dixie cups away and fill the film canister with MEK, running that through the primer pistol to clear it. All done.
 
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Hi Rick,

Can you tell us more about the primer pistol ? I haven't seen anything like that . I think one of the biggest hassles about priming/painting is the cleanup !

Marc
 
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.

The gentleman you're referring to is Randy Lervold. I don't know anyone in the world of RV's more knowledgeable than him, on most any subject related to RV's. He does a lot of research before making decisions. He built a beautiful RV-8 and later an incredible RV-3. He painted the interiors and exteriors of both of them. He was my EAA technical counselor for a while until he moved away from our area.

I used his methods as you describe and can attest that it works very well. Maroon scotchbrite pads followed by Naphtha (Coleman lantern fuel) is indeed cheap, very effective, evaporates almost immediately, and leaves a clean toothy surface for your primer. Randy tested various primers before settling on SEM. You can read more of his discussion about the prep work and priming right here:

http://www.romeolima.com/RV3works/Airframe/airframe.html#Primer

He was also instrumental in changing my mind about priming, after I had originally decided to just prime where ribs and skin surfaces join. I saw some pictures of a friends' RV-8 that had corrosion spots all over the skins (those pics, unfortunately, are no longer online as far as I can tell). After that, I decided I was going to prime everything (interior). I'm not saying that's what everyone should do. I just came to believe that for my RV, in the climate I live in, it's best.
 
Primer Formulation Question

I am leaning toward the Rattle-Can products as well. Thanks for the great link Bruce. But where do you find the SEM products? $12 per can on the internet is understandable but $11 shipping is a bit hard to swallow.

I found this Dupli-Color can at the auto-parts store. My plan is to use this (or the SEM product) on internal non-alclad parts only. How is this product formulated differently and what would be the performance differences between the two?

2011-01-14_10-16-55_334.jpg


One concern I would have is that it may not come in bulk volumes if I decided to prime all internal parts. The good news is that this can cost $6 and a bike ride! Will it cost me in the long run?
 
"First Step in Priming"?

I am leaning toward the Rattle-Can products as well. Thanks for the great link Bruce. But where do you find the SEM products? $12 per can on the internet is understandable but $11 shipping is a bit hard to swallow.

I found this Dupli-Color can at the auto-parts store. My plan is to use this (or the SEM product) on internal non-alclad parts only. How is this product formulated differently and what would be the performance differences between the two?

2011-01-14_10-16-55_334.jpg


One concern I would have is that it may not come in bulk volumes if I decided to prime all internal parts. The good news is that this can cost $6 and a bike ride! Will it cost me in the long run?

Says so right on the can! What is the next step?
I think you will find all of the self etching primers to be relatively equivalent in level of protection. According to Randy's site, he liked the SEM because it gave a better finish.
I suspect the "next step" would be a sealer or topcoat. I would be curious what the instructions on the can say.
 
But where do you find the SEM products? $12 per can on the internet is understandable but $11 shipping is a bit hard to swallow.

Automotive paint store. I really like the SEM rattle cans for touch-ups or smaller parts, but it is also available in quarts if you wish to go that route. My larger scale priming has all been done with Dupont Variprime, which I like very much, but if I were starting over today, I'd certainly consider going with all SEM.
 
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