Alodine and self etch primer?

I just finished watching the Sam James DVD on painting your aircraft and am more confused than I was before I watched it. I have been using Sherwin Williams self etch primer on all my internal pieces of my 9A. I read somewhere that not only was the alodine process not needed when using a self etch primer can be detrimental to the final outcome. In the Sam James video he goes through the whole acid etch, alodine process and then sprays Dupont VariPrime self etch primer. I thought that was the whole purpose of a self etch primer to not have to do the acid etch and alodine. Please would someone fill me in?

Thanks

The point of self-etch is to not have to do the etching process with alumiprep, for example. If you're alodining, you will have to etch regardless, I believe. There's no purpose in etching after alodining, though, as the alodine acts as the base for the primer. I don't think it's particularly detrimental. Then again, this is just a fairly uninformed guess, which brings me to the real answer....

The best thing to do is use a complete paint system from one company....Dupont, for example. They will have the complete system from begining to end that will do 100% of what you need and everything is compatible. At a minimum, they will tell you EXACTLY what additional steps are nescessary (i.e. treat with bladdidy-blah acid etch or equivalent....something like that).

Painting's a huge job. I'm curious: does it really save that much over a pro paint job? The materials and equipment are so expensive, I think. I don't know. Maybe you can give an estimate how much you save painting yourself?

Thanks John,
I have no desire to paint my own airplane. I just see too many ways to screw up a nice airplane. I am priming the insides of everything just because I hope it will add some value if I decide to sell the plane one day. I'm 55 and who knows what next year may bring. I hope my health will let me fly for another 10 years and then maybe convert to sport pilot.
My opinion is if you figure all the expense of painting your own including building a paint booth and painting materials you won't save anything and may very well cost you money because of resale value.
On the other hand, if you are a person that likes to do everything involved in building your own plane then my hat is off to you. One of the nicest paint jobs I have ever seen on an RV was done at home.That is what this hobby is all about.
I enjoy the assembly of the airplane and I like working with the engine and electrical but hate fiberglass and don't like noxious chemicals. I want this to be an enjoyable experience all the way through so I will leave the paint to the professionals.

If you want to use self etching pring just make sure your area is scuffed and very clean. If you plan on painting, don't use Vari Prime.

Jim,
Self etching primers actually contain a small amount of acid etch right in the primer. Thus spraying a self etching primer over an Alodined surface will degrade the quality of the Alodine process. Have you read DuPont's recommendions regarding VariPrime? If you had, you would know that VariPrime is NOT recommended as a finish surface for alumimum. DuPont recommends applying another primer or finish coat over VariPrime. VariPrime does not create a vapor barrier (it's porous and doesn't stop water from moving through it) and contains no corrosion inhibiting metals such as zinc chromate or strontium chromate.
Due to the two limitations above, why would you want to use VariPrime? I would suggest that you use a Mil-Spec epoxy primer, like Akzo, Deft or Sterling U1201/U1202. There are a number of other similar products. All Mil-Spec epoxy primers contain strontium chromate.
Since you've gone to the trouble to "do it right" by Alodining the material, why not use the best type of primer? There is no increase in work level for you.
VariPrime's only advantage is that it saves work for the lazy. When it comes to corrosion control, that old Bally Health Club TV ad comes to mind. (You know the one, with Cher) Cher states in the commercial, "If great bodies came in a pill, everyone would have one". The same applies to prep/paint work, if you want great results, you have to apply elbow grease. There are no "free lunches".
Cessna offers a 30 year warranty on their new airframes. Why? Because they apply Alodine and epoxy primer to every part of the airframe. It takes BOTH chromic acid conversion (aka Alodine 1201 or Iridite 12-4) AND a mil spec epoxy primer to prevent all 8 types of corrosion on an aluminum surface.
To learn more, go check out the Technical Article section of EAA Chapter 1000's web site. See

http://www.eaa1000.av.org/technicl/corrosion/corridx.htm

As for the previous lister who recommends using a "system" from one manufacturer, while good advice, it's not the "only way to go". By definition, epoxy primers are inert, once dry. Therefore, you can finish paint them with ANY type of finish paint from ANY manufacturer, without problems.
Using a "system" of paints which are designed for use on steel will gain you NO corrosion inhibiting or paint adhesion advantages. Primers designed for use on steel will NOT adhere to aluminum as well as primers designed for use on aluminum. Most automotive primers are designed for use on steel, not aluminum.
VariPrime is designed for use on aluminum. However, it's intent is as a cheapo, cost cutting, labor saving solution. Since you have already Alodined your parts, you gain nothing by using it. The etch acid it contains will actually remove a portion of the Alodine treatment you have already applied.

Charlie Kuss

It seems odd that Cessna is offering a 30 year warranty on its new planes because of using epoxy paint on the insides of the planes. My 1957 Cessna was nearly 50 years old when I sold it.and had almost no corrosion and it is shiny alclad aluminum with no primer. Surely Cessna hasn't stopped using alclad aluminum in their planes. If it wasn't for an added value perceived by a potential customer I wouldn't have primed any surface that was alclad.

rv9aviator said:

It seems odd that Cessna is offering a 30 year warranty on its new planes because of using epoxy paint on the insides of the planes. My 1957 Cessna was nearly 50 years old when I sold it.and had almost no corrosion and it is shiny alclad aluminum with no primer. Surely Cessna hasn't stopped using alclad aluminum in their planes. If it wasn't for an added value perceived by a potential customer I wouldn't have primed any surface that was alclad.

Click to expand...

Jim.... I bet your 50 year old Cessna never spent much of it's life in coastal Florida....

gil in dry Tucson ... except for this July....

az_gila said:

Jim.... I bet your 50 year old Cessna never spent much of it's life in coastal Florida....

gil in dry Tucson ... except for this July....

Click to expand...

Gil,
OUCH! Talk about rubbing salt (spray) in the wound!
Charlie Kuss

I agree that if I lived on the coast I would be much more concerned but I am in Arkansas and the plane will be hangered. I guess whoever buys my plane someday can get a jug of corrosion X and marinate the plane in it.

My local paint shop owner gave me these gems yesterday:
1. Either self etch prime or alodine. Not both on any one piece of metal.
2. Krylon and Rustoleum are for lawn furniture not cars (or airplanes).
3. Any rattle can of paint contains 25% paint, 70% propellant, and 5% thinner

Steve

Steve,

Good advice. However, Rustoleum works just fine on the internal parts. Go figure. Of course, if you could paint your own airplane with a spray can, how would the local paint shop owner pay his bills.

Tracy.

rv9aviator said:

I agree that if I lived on the coast I would be much more concerned but I am in Arkansas and the plane will be hangered. I guess whoever buys my plane someday can get a jug of corrosion X and marinate the plane in it.

Click to expand...

I hate corrosion X!!! Really, only because 99.9% of mechanics in the world don't know how to apply it correctly.

By definition, epoxy primers are inert, once dry. Therefore, you can finish paint them with ANY type of finish paint from ANY manufacturer, without problems.

Click to expand...

Has anyone painted over Akzo? What prep? What results?

Thanks,

tomcostanza said:

Has anyone painted over Akzo? What prep? What results?

Thanks,

Click to expand...

Yes, with excellent results. If finish paint is applied within 48 hours, just apply the finish paint. If painting is going to be delayed beyond that time, apply an additional coat of Akzo. When ready to paint, wet sand the surface with 320 grit paper. You only want to rough up the primer, to allow the finish paint to get a good "bite". Avoid sanding through the primer, as this will remove any Alodine under the primer and require additional "touch up" work prior to finish paint. The additional coat of primer is there to prevent breaking through the primer when you wet sand later.
Charlie Kuss

Rustoleum is good?

Really?...tell that to my panel that I have to repaint...Uses Rustoleum super durablilty white hard as nails paint....Its chipping off quite nicely...After i get bored with flying my new bird I will pull the panel and paint it in body colour...Maybe after about 1000 hours or so...

Speaking of paint I took a tip from the ex autobody worker in the paint store...I acid etched all my external panels with Vinnegar.....Yup, cheap and easy.

Then uses Valspar Omega 2k superfil primer and top coat system.

Hasn't fell off yet...

Frank

frankh said:

snipped
Speaking of paint I took a tip from the ex autobody worker in the paint store...I acid etched all my external panels with Vinnegar.....Yup, cheap and easy.
snippedFrank

Click to expand...

Frank,
Did you use White Apple vinegar or Balsalmic? Since vinegar is an acid, I see how it would work well. Plus it's biodegradable. Nice "low budget" tip.
Charlie

Rustoleum works for me

Frank,

I have made a number of small test panels over the past two years using Rustoleum. For my first two panels, I sprayed one panel with primer, and one without primer (just a note, my primer was AFS, not spray can primer). I roughed-up both panels with Scotch-brite, then cleaned them with lacquer thinner prior to painting. These were tossed around the shop for two years, without ever chipping, or losing any paint. They have both since been repainted for my label tests, so two years is as far back as this test goes.

Over the last six months, I have been doing label tests with similar panels. Just to see how good Rustoleum would stick, I did a panel on 2024 with Alclad, without any preparation at all, other than to clean the part (i.e. a shiny smooth surface). A day later, the paint came right off using Scotch tape. So, without scuffing the surface, Rustoleum does indeed adhere pretty poorly. However, all of my other tests indicate that with minimal preparation, Rustoleum does seem to hold up.

Of course, all of my test panels are only about 3x4 inch pieces, so I do not have any testing with a larger surfaces. I'm not sure how that would affect ahesion, but it is a point to consider. Also, my shop does get hot and cold. but not as hot or as cold as an airplane left outside. Again, I am not flying, yet. These are just tests that I have done. One thing I might try is to make a test panel using the recommended primer, and one with Alodine underneath.

Tracy

Panels have screws

Which I have undone a few of and the Rustoleum immediately chips around the screw head.....Fourtunately I discovered this before i painted he exterior. I had already painted the cockpit side rails with Rustoleum...I stripped it all off and painted the side rails with the Valspar body colour.

The Rustoleum is interesting because a few years back I used the same stuff on my old airplane interior and it stood up pretty good...maybe they have changed the formula?

Anyway...I will strip the panel at some point and repaint with Valspar over vinegar.

Oh yes I used white distilled vinegar...Messy but cheap and good on french frys (known to us Brits as Chips)...Tip...The brits don't have anything to do with French things....

Frank

Etch/Alodine/Paint

Jim; Van sez his guys etched, then alodined, then shot 1 (one) coat of paint. !!
Rolly Clark
FWF RV-9

I agree with KTM520 Corrosion X can be a big pain in the but for painters.

I prefer to stick with the tried and true etch and alodine then Zinc chromate primer method when ever possible. Since aluminum is so tempramental to begin with, and one of the dirtiest metals on the planet. I like my surfaces to be as clean as i can possibly get them. If you dont want to get nailed by the enviormentalist, you could skip the alodine, etch it really well and then use epoxy primer.
but after all these are EXPERIMENTAL airplanes, right?

Hey KTM520 we should go ride some time I have a Street Legal CR250 (2stroke!!) it really messes with peoples minds to see the light blue smoke at a traffic light. But it is fully functional in the dirt, and on the track.. ( i been playing with some motard stuff lately got the 17" wheels and everything)

I use Sherwin Williams too... here is the straight scoop

Although I'm just a 60 year old hobbyist, my classic cars look quite good after I paint them. I even win trophies occasionally. I use Sherwin Williams (SW) products exclusively and spoke to the SW expert in Phoenix before I attacked my RV9A. Here are his comments:

BARE ALUMINUM ON RV9: This aluminum was coated with oil from the factory. God knows what other stuff has landed on the surface since my QB traveled to/from Europe.

1) Use aluminum cleaner ? W4-K263 DUAL ETCH METAL CLEANER AND CONDITIONER - Mix w/water 50/50, 2-1 or 4-1 and use the 2 rag method. One rag to apply cleaner, one rag to clean. I usually hose it off with clear water and use red scotch bright to apply.

Note that this stuff really stinks and can cause serious respiratory problems. It contains phosphoric acid which your nasal passages & brain will not appreciate so I wear a forced air respirator which delivers air from the adjoining room.

When the liquid cleaner stuff rolls off in sheets, you are done. Otherwise, repeat the process.

2) I used scotch bright during this process to also promote adhesion - wearing plastic gloves that don't disintegrate from the W4-K263, I scrub the surface with red scotch bright.

Forget alodine.

3) After the parts are dry, one hour before painting, wipe the parts with R7K156 cleaner. PPG calls this stuff Prep Sol. Use one paper towel to apply and another to remove. Move in one direction so what accumulates on the cleaner rag is not left behind when your hand changes position.

R7K156 is used to remove any final oils that can still be present. Don't ever touch the parts with your bare hands. That leaves oil. Wear clean plastic gloves. This stuff stinks too but I don't think it is as deadly as W4-K263.

4) After allowing the R7K156 to dry (and then some) prime with E2G980 ? 2 medium wets coats, 2 min flash time between coats. There is a reducer (R7K981) that goes with E2G980. Flows on beautifully. No runs, no sags, (no hits).

5) Urethane paint (I used this in the interior) ? We used the Dimension line (cheaper) with the appropriate hardener and reducer. Thus far, no matter how many things I throw at my painted parts, I have not chipped the paint.

For the exterior of the plane, I plan to use base coat and SW 7000 clear instead of urethane otherwise the prep process is the same.

Buy yourself an HVLP gun. The Sharp Finex 300 version can be purchased for under $100. For primer, get the bigger tip and nozzle. The amount of overspray is literally cut by more than half. U save lotsa $$ and Mother Nature will thank you.

Make sure your compressor has a water filter in line with the air else you'll blow water into the paint. Ditto for an oil separator. Drain the tank before starting.

Buy a good regulator and position it at the gun (after the final, second, inline, disposable air filter). Regulators can be purchased for $7 or $30. Guess which one actually works when the compressor drops in pressure?

Don't even think about shopping at Harbor Freight.

Create a paint booth environment that blows the fumes and overspray into a wet towel hanging in the airstream so your neighbor's car sitting outside your window does not come out green. Capture the overspray into the wet towel instead of asking Mother Nature to ingest it.

Put in lots of light cause if you're 55, you're gonna need it to "see the flow" your Finex gun will apply to the surface. I'm 60 so I can appreciate your desire to fly for 10 more years. Work with a test piece before attacking the plane. I use a picture of my mother-in-law for test spray. Until the fan and volume looks good, keep testing.

And convincing the wife that you need a $600 forced air respirator is easy. Show her what chemo costs.

I also watched the video. His spray pattern was round instead of parallel to the item you're painting. That's just dead nuts wrong. Your arm should be an extension of the gun, maintaining an equal, perpendicular distance from the target at all times.

Squeeze the trigger before the paint gun arrives at the piece. Release the trigger after you pass over the entire piece. Never squeeze the trigger while over the target. He did that a few times too. No matter how good the regulator, there is a drop off when the trigger is squeezed.

Hope this helped.

Barry

Paint cost

jcoloccia said:

Painting's a huge job. I'm curious: does it really save that much over a pro paint job? The materials and equipment are so expensive, I think. I don't know. Maybe you can give an estimate how much you save painting yourself?

Click to expand...

Using Sherwin Williams products, good stuff, I figure primer will be $500. My design scheme calls for two colors and separator colors. Using base coat / clear coat I expect to use two gallons of base (white and yellow which are less expensive than red) & approp reducer ($800), plus two gallons of clear and approp reducer/hardener $800.

Total = $2k (approx) for materials and many hours taping because I plan a complex scheme. If I color sand the clear, add another 200 hours. I'm old and slow.

One day should be required to paint the fuse on a rotisserie, one day per wing (also on a rotisserie), and one day for tail feathers. The shop is only 20x24 and I'd rather spread the workload over 4 days than bump into wet parts.

This presupposes you have the approp guns (a decent Sharpe hvlp is $100, primer guns are cheap or get a large cap for your Sharp), 5 hp compressor (or more), water separators ($70), regulator and good breathing apparatus. Lites galore, and a room that's properly ventilated.

Don't scrimp on the breathing equip. There are so many carcinogens in this stuff it's scary. Home Depot masks just don't cut it. If you can smell, you're breathing it.

This also presupposes you know how to paint. Of the many tasks involved in building a plane (thus far we're half done), none requires the steady hand of a paint gun and the feel of when paint is just wet enough to give you a good flow but not too wet to run down the side of the panel.

Practice and read.

What would a pro charge for base coat / clear coat? Yes, if you use single stage urethane you can save approx $1000 but single stage is actually harder than base coat / clear coat.

Self Etch Primers

Jim,

Don't go over an alodine piece with self etch primer. Think of it like this...

Take a part and acid etch it, then alodine it for Corrosion protection, it does a surface conversion to the metal then prime it with a two part epoxy primer.

Simple when doing a small part, however think of a rudder skin, how are you going to dip it in alodine? True you can brush it on but what a hassle. This is where you use a self etching primer to prevent the acid etch and alodine process. The self Etching primer has an acid in it that will flash off when it drys but allows the primer to bond to the metal but DOESN'T seal the metal from moisture, you must go over it with a two part epoxy to seal the self etching primer. So use self etching primer to avoid acid etching and alodine but then prime with epoxy primer to seal.

There is a comprehensive explaination on www.txrv10.com under knowledgebase, then select down arrow and primers. or follow this link http://www.txrv10.com/pages/primerpages/primermain.html
Dave

Jim,

Don't go over an alodine piece with self etch primer. Think of it like this...

Take a part and acid etch it, then alodine it for Corrosion protection, it does a surface conversion to the metal then prime it with a two part epoxy primer.

Simple when doing a small part, however think of a rudder skin, how are you going to dip it in alodine? True you can brush it on but what a hassle. This is where you use a self etching primer to prevent the acid etch and alodine process. The self Etching primer has an acid in it that will flash off when it drys but allows the primer to bond to the metal but DOESN'T seal the metal from moisture, you must go over it with a two part epoxy to seal the self etching primer. So use self etching primer to avoid acid etching and alodine but then prime over the self etching primer with epoxy primer to seal.

There is a comprehensive explaination on www.txrv10.com under knowledgebase, then select down arrow and primers. or follow this link http://www.txrv10.com/pages/primerpages/primermain.html
Dave

WOW!

I can't believe this thread has been circling the drain for two years now. I am almost through priming everything that needs priming and have learned a couple of things. Sherwin Williams self etch (P-60) is plenty good enough for the insides of my plane and for Van's quick builds for that matter. I used dish soap and hot water with a red scotchbrite pad to clean all the surfaces that were primed. Right before I sprayed the primer I wiped everything off with a cloth with a little lacquer thinner on it then lightly went over the parts again with a tack rag. The P-60 is fairly hard and doesn't soak up oils and grease like Vari-Prime does. I won't use that again.

I primed all the interior pieces of the cabin area, like the floors and seat backs, and then top coated them before installing them which looking back wasn't such a great idea. There is no way to keep all those parts looking nice until the plane is ready to fly. I should have used an Epoxy primer on the interior parts and let it go at that until the plane was all but finished. They tell me you can lightly sand the epoxy primer even six months later and seal then top coat it. It supposedly doesn't draw moisture like normal primer dies. If I'm giving bad information please correct me, but I've heard this from several sources.

My long term plan (12 months or less I hope) is to be able to fly the plane to Grady's and have him work his magic on the outside of the plane.

BTW Mel, Save me a spot this time next summer for an inspection This my goal and am working hard to make it happen.