Stewart Systems Ekopoxy

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With Heat Pack option adds a shipping heat pack to keep the material from freezing while in transit. It is recommended for winter months / destinations in cold climates where the temperature may drop below freezing while in transit. If the material freezes, it is not recommended for use.

Stewart Systems EkoPoxy Primer/Sealer is a high quality water based Epoxy primer for use on many substrates. Stewart Systems EkoPoxy can be used on interior and exterior surfaces where there is more chance of corrosion from the environment. Excellent adhesion to bare metals, resists flash rusting which can occur with latex based primers. Stewart Systems EkoPoxy has superior chemical resistance, is fast drying and mar resistant. Stewart Systems EkoPoxy is low in VOCs and compatible with a wide range of top coats including EkoPoly Top coat. Nonhazardous, nonflammable and water cleanup, Stewart Systems EkoPoxy is your best choice for Primer.

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I really like this 2-part epoxy primer. The water-borne aspect and minimal fumes are a huge plus. But the real bonus is the toughness of the primer compared to rattle can primers (or even their 1-part Eco-Prime). Ive used Eco-prime too and found this to be MUCH tougher. Its pretty easy to mix using a small and extra small mixer attached to a drill for the 2 different sized cans. For those that complain that it is too difficult to use, I disagree. There is a learning curve to any 2-part epoxy primer and I did buy a HVLP spray gun meant for water-borne finishes. But by following their instructions and their videos, Ive found that it sprays just as well as any other solvent-borne finish Ive used over the years. It dries fast too. I just ordered my 5th quart and will be finishing my aircraft build using Eco-Poxy.

Jeremy B
January 30, 2024

As a homebuilder that has been futzing with rattle-can zinc primers for about half of my build, this 2-part primer is a godsend. I wanted something durable for the visible cockpit area, and now that Ive started using it and everything looks so nice, Ive been priming all the fuselage parts I can! Having no experience with real painting tools (e.g., HVLP sprayers), I did need a little bit of debugging of my spray setup when I started using it, such as avoiding the paper mixing cups I had been using for small batches of hobby epoxy, etc., in favor of plastic. As other reviewers have mentioned, Ive had good success with the small touch-up spray guns thinning the primer slightly with greater than the recommended 13% water weight (maybe 15-16% so far seems to work well). My only gripe is it could be less expensive 🙃

Brandon B
April 8, 2021

Ive used the EkoPoxy to prime my metal Zenith. When opening the product, I thought it had gone bad. You must use a powered (drill) attached mixer tip and stir 10 minutes to get a creamy texture. This is common for this product, its not bad. Add 18% by weight (grams) catalist and 13% by weight water. Mix and spray. I used a 1.3mm tip. No difficulties with spray. Primer dries quickly. Second coat in 10 minutes. This stuff is tough and durable. Sanding is necessary.

Kenneth E
October 21, 2020

I have used this on my last project and like it very much.

James B
August 25, 2019

I used SS primer during all my RV8 construction. Very satisfied... tough as nails primer adhesion, providing the surface is well treated prior. Removed one star as the catalist in the quart I received had thickened somewhat, though still usable. Batches I’ve received in the past were more liquid. I’m suspecting this batch sat on a shelf for considerable length of time before being shipped, which will likely reduce my remaining shelf life.

September 29, 2020

I tried applying this with a couple of different spray guns, and used a weight scale with 0.01 gram accuracy to measure, tried more and less water. No joy. When sprayed, If wet enough it runs, if not wet enough it pebbles (worse than a run because now you have to sand it all off because it did not wet out). Forget spray, go with a tiny foam roller. It wont run, and will fully wet out every pass. And, thanks to its odd quick setting action, you can recoat/reroll within minutes. I am doing a pair of c172 wingtips, with a roller I can fully roll and wet out one tip then the other and by the end of the second one then the first one is ready to recoat. Takes 4 coats but you can bang them all out with a roller about as fast as you can roll. Now let them sit overnight. In the morning they will be soft. Spray them lightly with black guide coat (lightly!) from the automobile paint store it will help with sanding. But after guide coat is applied now they are dark grey or nearly black, or at least dark so set them in the sun to bake. Do not apply a coat of guide coat, just a an incomplete light mist so the primer can breath through the guide coat. Being black/dark heats them in the sun and sets the paint HARD. 1 or 2 days in full sun. Once baked and hard sand with 220 grit just until the guide coat disappears. Nice finish now. ready for paint. No idea how to bake a whole airplane, probably cant, go on vacation for a week or two instead. Leave the hangar heat at 80f. Nice water cleanup and not stinky.

John G
June 22, 2020

I have previously been using a self etch zinc phosphate primer, and now that temperatures are warm enough, I have switched to using EkoPoxy. It is way less pungent (my etch primer stinks days after application) and seems to apply well (I am using it as a primer on interior components. Appears to adhere better than the etch primer (doesnt marr readily when riveting), and can be applied with a small touch up gun (0.5mm nozzle) if you add more water (+50%) to thin it (although the manufacturer recommends only applying with a 1.5-1.8mm nozzle). Only time will tell its true corrosion resisting potential. All said, Im very impressed, and its so nice not to have pungent VOCs around you the whole time (but still wear good respiratory equipment).

November 27, 2015

I decided to try this low VOC primer because Im forced to do my priming in my attached garage this time of year. It was definitely good for that purpose as there was almost no smell to it. Spraying it however is not easy. Im no professional but I have built two aluminum airplanes and have done a fair bit of priming on those aircraft and this primer is by far the hardest to get a good coat on. Its only been a little over a week since I sprayed the primer so its still not at full hardness but so far it seems like it sets up better than any rattle can primer but not quite as hard as an epoxy such as Azko (which sprays very nicely...maybe Im spoiled). Oh, one more thing, it does not appear to be compatible with JetFlex WR interior coating I use.

Darin A
April 9, 2020


Please note, Aircraft Spruce's personnel are not certified aircraft mechanics and can only provide general support and ideas, which should not be relied upon or implemented in lieu of consulting an A&P or other qualified technician. Aircraft Spruce assumes no responsibility or liability for any issue or problem which may arise from any repair, modification or other work done from this knowledge base. Any product eligibility information provided here is based on general application guides and we recommend always referring to your specific aircraft parts manual, the parts manufacturer or consulting with a qualified mechanic.

Q: Can this be applied over an airframe that has been primed with automotive primer or over zinc chromate?

Per the supplier: It is compatible, but the surface must be prepared properly, and be sure the existing primer was properly applied.

Q: Does this product need to be reduced for application with a spray gun? Can it be reduced with water? How much does one gallon yield after reduction??

The preferred method of application is a spray gun. You can reduce with water, you would need about 1 pint for this kit. When you mix parts a and b with the water in the gallon kit, it yields 5-1/2 qrts.

Q: Can your Stewart System Ekopoxy be applied with a roller?

The vendor recommends spraying it per the tech data sheet. We believe it would be too thin to roll on.

Q: Can you provide an estimate for how much EkoPoxy would be needed to coat the inside of a four place single engine plane (excluding the floor surface)?

Per the vendor, 1 quart would be enough.

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