I'm getting ready to paint the interior of my old Skylane, and I've been researching for weeks a method to accomplish this with minimum toxicity, the fewest steps, and the best results. I'm read everything I can about the Primer Wars. I loathe Cessna interior plastics, and I've been inspired by others' projects here, so here we go!

Here's the method I've settled on, and I wanted to solicit input:

1. Thoroughly clean out the interior. Remove old adhesive with Peerco and other products. Get the aluminum really clean.
2. Scrub/scuff the aluminum with scotchbrite and then do a rag down with acetone.
3. Spray in Super Koropon BMS 10-11 Type I Class A Grade A. This is a solvent-based 2 part epoxy, like Akzo. Pretty much same stuff.
4. Wait a week and spray in Ranthane as a topcoat.

Due to the chromate in the primer and the toluene in the urethane paint, this is all pretty nasty stuff and will require a full suit up with respirator. But the idea is to avoid the whole alumiprep/alodine prep stages. We're concerned that doing any kind of acid etch inside the plane leads to two problems because it has to be thoroughly rinsed off: 1. some of it may get under the flooring or into other hard to clean out spots, and 2. we don't have a safe way to deal with the waste water. Alumiprep and alodine are both toxic to deal with, as well.

I like the idea of using Stewart Systems, but that route still requires an acid etch step of some kind, and I'm also concerned about water-based primer being a bit more finicky. We're doing this inside a heated hangar in December, but it'll still be winter and there may be some temperature fluctuations. The consensus also seems to be that the solvent-based primers are tougher and adhere more strongly.

Once the interior is nicely cured, I'm putting in some Selkirk 1/2" foam.

So, thoughts?

Clean, scuff and acetone then spray direct with Tremclad. It will look good and stay forever and easy to touch up if you do scratch it.

I agree with 175 Magnum. For the aircraft interior you need not get too fancy. Tremclad or even a rattle can of Rustoleum will last a long time and can be touched up easily. Sounds like you realize the importance of a clean surface. I would save the chromium based primer for the exterior, and use a basic metal primer for the interior. I have had very poor long term results with self etching primer from a rattle can on clean aluminum. I also had poor results with Rustoleum paint over Napa's brand of zinc chromate primer. Rustoleum paint over Rustoleum grey primer is very adequate for interior stuff. I don't mean to sound like an expert, as I'm not. Just stating my experience.

What about Veriprime over clean AL then paint before the window closes on the primer?

Based on my research, there are many ways to skin this cat, and prep is the most important thing. That said, many people have confirmed that self-etching primers just aren't necessary. One pro paint shop I talked to recommended just cleaning the aluminum thoroughly and then hitting it with a 2 part epoxy primer. The epoxy primers create a very strong mechanical bond, and this can be improved with some abrasion. Plenty have used Dupont's Variprime to good effect - I just don't know that it's necessary.

And I know some people still swear by the whole alumiprep route, but I'm concerned that some of that could get into the belly and even thorough rinsing may not eliminate all of it, setting the stage for future corrosion. It's also toxic as hell.

I appreciate getting some first hand accounts of using aerosols. There are horror stories out there, for sure, but you have to wonder if the problems arose due to the aerosol? Or due to poor prep? This would be the easiest method.

From lots of previous experience, Stewart's will do just fine. You can bypass the etch by scuffing with clean scotch brite pads and use isopropyl alcohol to clean with. Get it as clean as you can and go for it.

As for your initial post, Tolulene in the urethane, although not good, is not your worst enemy! The isocyanide in the catalyst is the real danger, and no resperator is going to control it enough in a solvent based application, to do you any good.Only the full suit and a fresh air supply will be effective. One thing many do not realize is that the absolutely most dangerous point with a catalyst is when you're mixing. The other thing is that it's not safe for days of outgassing.

Good luck,
John

A product that goes by the name of “Prekote” (search Aircraft Spruce) sells itself as an enviro friendly alternative to alumiprep/alodine.

I can’t speak to its effectiveness, but it’s likely better than no prep at all.

Chris

Whale wrote:3. Spray in Super Koropon BMS 10-11 Type I Class A Grade A. This is a solvent-based 2 part epoxy, like Akzo. Pretty much same stuff.
4. Wait a week and spray in Ranthane as a topcoat.

I thought that Super Koropon had to be topcoated within 24 hours....or you had to sand/scuff the entire surface again...?

Chris


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hardtailjohn wrote:From lots of previous experience, Stewart's will do just fine. You can bypass the etch by scuffing with clean scotch brite pads and use isopropyl alcohol to clean with. Get it as clean as you can and go for it.

As for your initial post, Tolulene in the urethane, although not good, is not your worst enemy! The isocyanide in the catalyst is the real danger, and no resperator is going to control it enough in a solvent based application, to do you any good.Only the full suit and a fresh air supply will be effective. One thing many do not realize is that the absolutely most dangerous point with a catalyst is when you're mixing. The other thing is that it's not safe for days of outgassing.

Good luck,
John

I certainly took your warnings about isocyanates to heart before I did the painting on our experimental. I appreciate your willingness to pass along that knowledge. I don’t think I’d paint anything without the fresh air and full face covering.

I noticed some of the Rans parts we got were very scuffed from the factory. I know the builder I helped on the S20 cheated on some of the small parts with straight rattle can. Paint is still on there too.

John, have you used the EkoPrimer or the EkoPoxy? SS really, really promotes using their etcher, and responded to my inquiry with: "adhesion is better with it" and "EkoPoxy is more resistant to solvents". Great, read that much on their website. If anyone has used the EkoPrimer on "merely" scuffed, clean aluminum, I'd like to hear about it.

My IA is experienced with a paint gun, and has had sub-optimal results with rattle cans, so we are spraying! The question is, do we spray Rustoleum's aluminum primer (from a quart container)? Or go with SS? And if the latter, will EkoPrimer with a topcoat of paint be enough?

If going with SS you need to order sooner then later. I just got an order and I'm hoping it didn't freeze on the way up.

Eko Primer is probably fine, however I find Dupont's chromium based epoxy primer easier to sand. I stopped using the Eko for that reason. I don't think the Eko I used was chromium based, but maybe it was. The Dupont Chromium based primer is not available for sale in New England, so I order it from Blue Ridge Paint in Kansas City, Missouri. Great corrosion resistance, but you need a fresh air supply to spray it.

I used both Stewart’s Ekopoxy and Ekoprime on various skins the inside of this plane. Most of the skins and panels were etched (the process is way nicer than alodine) prior to spraying. Some were just wiped down good with alcohol. Six years later (stored outside all year) the finish has never peeled and is still hard to scratch. Its tough to even remove with MEK although for some reason Acetone does a better job. The seat pan has withstood all the punishment of being a resting area for bucking bars and tools and still looks great. I applied the ekopoxy during the winter with a small heater in the garage that had the temp around 50F. At those temps it takes about a week to FULLY harden. Once the water fully flashes out of the chemical it looks and feels like any other epoxy primer. Just my observations. Would I use it again…..in a heartbeat. Some of the cabin walls soundproof foam was applied as well.

Whale wrote:John, have you used the EkoPrimer or the EkoPoxy? SS really, really promotes using their etcher, and responded to my inquiry with: "adhesion is better with it" and "EkoPoxy is more resistant to solvents". Great, read that much on their website. If anyone has used the EkoPrimer on "merely" scuffed, clean aluminum, I'd like to hear about it.

My IA is experienced with a paint gun, and has had sub-optimal results with rattle cans, so we are spraying! The question is, do we spray Rustoleum's aluminum primer (from a quart container)? Or go with SS? And if the latter, will EkoPrimer with a topcoat of paint be enough?

Sorry it took me this long to answer...I was just starting to, last night, when the power went out....it just came back up about 2 hours ago.
Yes, I've used them both. I'm a tech rep for them and actually used to own part of the company before it became "Stewart Systems". I'm still a tech rep and instructor for them.
Yes, the adhesion might be a little better with a good etch application. Especially for the average person, doing a project, as it gets a much more even and thorough mechanical bond for the primer to adhear to. That being said, you can provide a very adequate tooth adhesion with a good, thorough scuffing and carefully cleaning afterward. There's always more than one way to "skin a cat".
As they said, Ekoprime is not quite as "tough" as the Ekopoxy, although Ekoprime is a bit more flexible and sands easier. They're both tough and would work fine for your task, but the Ekopoxy would be my choice for your application. I would also scuff the primer, when you go to shoot the topcoat. I've had good luck with both. Try to keep the temp up above 50, and as said above, it's going to take a while to completely dry...forget the 24 hour recommendation, if it's not at 70 with airflow.
John

hardtailjohn wrote:

Whale wrote:John, have you used the EkoPrimer or the EkoPoxy? SS really, really promotes using their etcher, and responded to my inquiry with: "adhesion is better with it" and "EkoPoxy is more resistant to solvents". Great, read that much on their website. If anyone has used the EkoPrimer on "merely" scuffed, clean aluminum, I'd like to hear about it.

My IA is experienced with a paint gun, and has had sub-optimal results with rattle cans, so we are spraying! The question is, do we spray Rustoleum's aluminum primer (from a quart container)? Or go with SS? And if the latter, will EkoPrimer with a topcoat of paint be enough?

Sorry it took me this long to answer...I was just starting to, last night, when the power went out....it just came back up about 2 hours ago.
Yes, I've used them both. I'm a tech rep for them and actually used to own part of the company before it became "Stewart Systems". I'm still a tech rep and instructor for them.
Yes, the adhesion might be a little better with a good etch application. Especially for the average person, doing a project, as it gets a much more even and thorough mechanical bond for the primer to adhear to. That being said, you can provide a very adequate tooth adhesion with a good, thorough scuffing and carefully cleaning afterward. There's always more than one way to "skin a cat".
As they said, Ekoprime is not quite as "tough" as the Ekopoxy, although Ekoprime is a bit more flexible and sands easier. They're both tough and would work fine for your task, but the Ekopoxy would be my choice for your application. I would also scuff the primer, when you go to shoot the topcoat. I've had good luck with both. Try to keep the temp up above 50, and as said above, it's going to take a while to completely dry...forget the 24 hour recommendation, if it's not at 70 with airflow.
John

John, just curious if you or Andy have tried or know anyone who has tried painting SS with the new Graco cordless spray guns?

Excellent. Thank you everyone for the input. I've ordered the EkoPoxy. I'm going to try using PreKote wipes after the cleaning and scuffing, to enhance chemical bonding. The PreKote wipes don't require a rinse stage. You just wipe down, allow to dry, and prime. I WILL provide pictures and report on progress.

A1Skinner wrote:

John, just curious if you or Andy have tried or know anyone who has tried painting SS with the new Graco cordless spray guns?[/quote]


I have not. Andy and I talked about that a while ago, and he hadn't either, although we're both very curious about it. Technology has come a long way! If you have one, I'd LOVE to see some testing done!!
John

gbflyer wrote:

I certainly took your warnings about isocyanates to heart before I did the painting on our experimental. I appreciate your willingness to pass along that knowledge. I don’t think I’d paint anything without the fresh air and full face covering. .[/quote]


Thanks, I just don't wish the health problems possible on anyone!! I've been through some of it, and it's no fun!
John

hardtailjohn wrote:

A1Skinner wrote:

John, just curious if you or Andy have tried or know anyone who has tried painting SS with the new Graco cordless spray guns?

I have not. Andy and I talked about that a while ago, and he hadn't either, although we're both very curious about it. Technology has come a long way! If you have one, I'd LOVE to see some testing done!!
John[/quote]I'm hoping to paint another Scout using one here this winter. I'll report to you how it works.

Whale wrote:Excellent. Thank you everyone for the input. I've ordered the EkoPoxy. I'm going to try using PreKote wipes after the cleaning and scuffing, to enhance chemical bonding. The PreKote wipes don't require a rinse stage. You just wipe down, allow to dry, and prime. I WILL provide pictures and report on progress.

The only thing I could add is that as far as I know, we've never done any testing with it. It certainly sounds interesting!
John