Stewart Systems Paint

[Ron Earp]

I'm in the middle of building my plane and getting to the point where I need to start thinking about exterior paint. For all of my interior priming needs I've been using the Ekopoxy from Stewart Systems, which I see a fair number of other folks are using as well. Ekopoxy is a two part water based epoxy which they've long recommended for metal aircraft. EkoCrylic is the top coat that is to be used with the Ekopoxy on metal planes.

However, over the last month or so, Stewart has been having problems with their OEM supplier for their EkoCrylic. According to the rep I spoke with they have not identified what the issue is and are uncertain when EkoCrylic will be available again. They're recommending customers use EkoPoly, which is their paint formulated for fabric aircraft.

Anyone have experience with EkoPoly? I'm a bit concerned about using it since EkoCrylic was the paint they claimed as formulated for metal aircraft. I would expect significant differences in a paint formulation for metal vs fabric, and would rather not use a "somewhat suitable" paint just to stay in the Stewart paint system.

 

[lr172]

I'm in the middle of building my plane and getting to the point where I need to start thinking about exterior paint. For all of my interior priming needs I've been using the Ekopoxy from Stewart Systems, which I see a fair number of other folks are using as well. Ekopoxy is a two part water based epoxy which they've long recommended for metal aircraft. EkoCrylic is the top coat that is to be used with the Ekopoxy on metal planes.

However, over the last month or so, Stewart has been having problems with their OEM supplier for their EkoCrylic. According to the rep I spoke with they have not identified what the issue is and are uncertain when EkoCrylic will be available again. They're recommending customers use EkoPoly, which is their paint formulated for fabric aircraft.

Anyone have experience with EkoPoly? I'm a bit concerned about using it since EkoCrylic was the paint they claimed as formulated for metal aircraft. I would expect significant differences in a paint formulation for metal vs fabric, and would rather not use a "somewhat suitable" paint just to stay in the Stewart paint system.

Only the primer needs to be compatible with metal. The top coats do not come in contact with metal and therefore no compatibility need. The top coats DO, however, need to be compatible with the primer. FYI, most of the quality Epoxy products out there are DTM compatible. - Direct To Metal. There is nothing really unique about "aircraft metal" It is just metal, aluminum in this case. But not much different than aluminum on a Ford truck. All that said, a top coat designed for fabric is going to have a need for a LOT more flex than paint over metal. This requires trade offs that may or may not suit your goals. The chemist plays with all the variables to build his version of the compromise and flex is one of those variables.

Never used Stewart, so can't comment. however, if this is your first paint job, I would stay away from water borne paints on the exterior. Never used, but told the initial learning curve is quite steep. Solvent based is more amateur friendly. Strongly recommend southern polyurethanes for epoxy primer and clear coat. MANY planes done with this primer.

 

[Ron Earp]

You've made a point that I was also concerned about, a fabric top coat seems to me would require considerable flexibility compared to an metal top coat. And I'd expect the paint to reflect those needs in its composition. Now, whether or not paint for fabric is perfectly suited for metal I can't say, but I'd expect the formulations to be different.

And this is my first airplane paint job. I've painted a couple of my own SCCA race cars with non-water based paints, to varying degrees of "that's acceptable track speeds". Of course with a track car I wasn't concerned about an awesome finish but with the airplane I'd like for the finish to be pretty decent.

I've already found that the water based primer does require some learned technique to spraying it. And I've seen more than a few users complain that the Stewart paint doesn't go on as smooth as other systems, but still, a lot of people here are using it.

What about single stage vs color and clear coat? What's the general consensus? Southern produce single and color/clear systems?

 

[lr172]

You've made a point that I was also concerned about, a fabric top coat seems to me would require considerable flexibility compared to an metal top coat. And I'd expect the paint to reflect those needs in its composition. Now, whether or not paint for fabric is perfectly suited for metal I can't say, but I'd expect the formulations to be different.

And this is my first airplane paint job. I've painted a couple of my own SCCA race cars with non-water based paints, to varying degrees of "that's acceptable track speeds". Of course with a track car I wasn't concerned about an awesome finish but with the airplane I'd like for the finish to be pretty decent.

I've already found that the water based primer does require some learned technique to spraying it. And I've seen more than a few users complain that the Stewart paint doesn't go on as smooth as other systems, but still, a lot of people here are using it.

What about single stage vs color and clear coat? What's the general consensus? Southern produce single and color/clear systems?

SPI has excellent base and single stage, however, they only have like 5 different colors. I am not picky and am VERY pleased with their quality, so just picked one of their available colors for my planes. Their SPI red is gorgeous and their pure white hides dirt really well. I did the 6 with their SS and did the 10 with their base/clear. I could write paragraphs on the differences, but in summary the SS eliminates the weak adhesion between the primer and base and therefore tougher on chips. The base clear is easier to apply without visible flaws and why ALL auto paint is base clear. SS tends to be used for things like trailers and industrial equipment that don't care much about perfection.

Be cautious with other brands of SS (It is really just clear coat with pigments), as most won't tolerate much if any sanding (a VERY thin layer of pure clear settles on the top and if you sand through it, the exposed pigments will show different hues), which is often required when spraying without a booth (i.e. dust removal) as well as fixing rookie mistakes. The SPI uses urethane pigments (expensive) so doesn't suffer from this issue. Most of the SS out there is designed for pro's spraying in a booth and don't need anything beyond a buff. You DO NOT want to be fixing a run in SS that doesn't use urethane pigments.

I would avoid the water based stuff. They outlawed the solvents in parts of Europe 5 or 10 years ago and the shops had fits getting used to it. Definitely possible to get good results, but not on your first job, from what I heard. I suspect this is the root of the Stewart complaints. Even the auto mfrs struggled getting it going and they have robots spraying. If you aren't yet able to lay down a nice finish with solvents, you are asking for trouble going to water borne IMHO.

 

[TroyBranch]

I have used the Ecopoly on fabric and metal. Never had any issues and used it as I didn't want two different paints. Not sure if the Ekocrylic goes down differently. Don't know what I would do if I could not get it for an all metal plane.

For those saying to not use water borne for a first time painter, I feel the opposite is true. Because spraying Stewarts is so different than solvents, you do not have the solvent spraying methods that don't work with Stewarts.

Painting is not easy with any paint and I much prefer the no smell of the Stewarts.

 

[Larry DeCamp]

Stewart poly vs solvent

LR172 says it very well.
Waterborne is much more sensitive to intercoat flash time, temperature and humidity. You can get pin holes in the finish coat when things go wrong.

I don't have any experience with cut and buff on SS Eckopoly. It sprayed ok with a finish just short of OEM cars, probably comparable Cessna in appearance. So, maybe someone else can comment on fixing orange peel and runs with Eckopoly.

Eckopoly is acceptably chemical tolerant. Gas, oil and solvents don’t bother it.

All that said, two stage solvent based will make you look like a pro. However, I am told by suppliers, ease of use and final results are directly proportional to price. I used $1200/gallon base/clear and it does make you look like you know what your doing.

 

[lr172]

All that said, two stage solvent based will make you look like a pro. However, I am told by suppliers, ease of use and final results are directly proportional to price. I used $1200/gallon base/clear and it does make you look like you know what your doing.

The SPI products are VERY high quality at an affordable price and an exception to the rule mentioned above. (small family run company in Georgia with no advertising or crazy overhead-they have grown purely by word of mouth). Their universal clear and epoxy primer were designed for amateurs and the clear is specifically designed for the unique environment of spraying in a garage vs a paint booth. You can get a very nice finish without being a pro. SPI started by selling paint products to the restoration crowd that was painting in their garage's and they still have a large following their, though they have expanded to several other areas, including aviation.

I hope that I don't sound like a promoter here, but it is not common to find high quality products selling a fraction of the price of their branded competitors high end products and just trying to share my find. I have painted probably 8 projects with SPI, including my two RV's and still can call Barry (Owner) almost 24/7 for questions and support. I still consider myself an amateur painter. I was talking to Barry the other day and happened to mention how lots of folks here like Kirker and Summit. He mentioned that he knows the people that make that paint. He went on to say that one of the key ways that they keep cost down is by using minimal amounts of UV inhibitors, which apparently are one of the more expensive components in the clear. He said that his clear has about the highest quantity of UV inhibitors on the market and continues to maintain that, as it just works and "that is how you build a reputation." They are good people, making a good product and selling it at a fair price.

 

[Ron Earp]

Thanks for the recommendation. I did give them a call yesterday and have color samples coming. I was bummed to learn they basically only have white, black, red, and orange. I had been planning on a yellow plane and will have to give this a lot of thought if I go with SPI as it'll be changing color scheme completely.

 

[lr172]

Thanks for the recommendation. I did give them a call yesterday and have color samples coming. I was bummed to learn they basically only have white, black, red, and orange. I had been planning on a yellow plane and will have to give this a lot of thought if I go with SPI as it'll be changing color scheme completely.

I have done several jobs like that. If you are going base/clear, you can buy your base coat from another supplier-all that compatibility talk is mostly marketing. Call the tech line (Barry) and ask him for a recommendation for a base coat. Tell him Larry from Chicago sent you. He knows all the lines out there and will give you a recommendation without getting clobbered on price. Be ready though. Reds and Yellows are pretty expensive from the big suppliers.

 

[bkervaski]

We have experience with EcoPoly ... suffice to say it's really really really hard to be consistent due to it's waterborne qualities and we ended up switching Airtech brand for top coat.

High marks for Stewarts covering system but I wouldn't use their top coats again. If I had a time machine I would use the Airtech covering system on my Carbon Cub project to avoid the hassle of a mixed system.

Also, Robbie at Airtech is awesome! He focuses on fabric but he has quality paints and primers for everything and they are really easy to lay down consistently.