Need Help on Stewart’s paint....cracks/chips/blisters

[adamgrenda]

My experimental cub was built in 2010 with Stewart’s system. It’s a great airplane and it looks good. It has some patches, duct tape and the typical rash of being a working hunting cub. However I’m concerned with the longevity of Stewarts system... I’ve had blisters that come and go that I just leave and hope they go away. A few I’ve popped and peeled the paint back and sanded and put down ekofill then ekoprime.

Overall the fabric doesn’t seem very flexible. If you push or pull anywhere it cracks. The stringers are all cracked down the tops and some on the sides of plane. The pull handles top coat is all cracked around the area. I’m not so concerned with the cosmetics of it I just want my fabric to last.

I can hold a headlamp light up to stringer and look through aft baggage door and see some light. Is that concerning? I have seen fabric much worse but my cub lives outside most of the year and I know what just a little UV can do.

If I can see daylight through stringer cracks what do I do? Do I lay new tapes? Do I sand and then lay more ekofill down? I’m not sure at this point. Called steward and they said they had some bad batches of paint around 2010 or so when this was done. Paint comes off when I pull the gorilla tape off in the winter months to patch it almost seems like I should just leave it on!? What about the vinyl guys are using to cover up some spots instead of a fabric patch?

Thanks.

 

[algonquin]

There is a seminar in Palmer Area the last weekend of this month that would answer your questions . The fellow putting it on is a factory rep.
It being put on by “Marty57 “on this site

 

[bob turner]

Sunlight turns Dacron to white dust in very short order. If you park outside, watch out for that. All fabric cracks along stringers. Most of the time it is not a big deal. Gear legs get beat up pretty quick - I have tried everything including 101 surface tapes. No luck.

 

[adamgrenda]

Sunlight turns Dacron to white dust in very short order. If you park outside, watch out for that. All fabric cracks along stringers. Most of the time it is not a big deal. Gear legs get beat up pretty quick - I have tried everything including 101 surface tapes. No luck.

So you have the same problem eh? At this point I would do whatever I just don’t want fabric dust!
I guess how much light is too much light

 

[Hardtailjohn]

Sounds like someone let the paint freeze before it was applied. And you're sure it's Stewart's paint?

John

 

[adamgrenda]

Sounds like someone let the paint freeze before it was applied. And you're sure it's Stewart's paint?

John

Yes it is.

 

[Marty57]

We have figured out some possible causes for the blistering issues. When you peeled back a blister, what did you find underneath? If it was bare fabric than the EkoFill separated from the fabric. We've traced that to EkoFill not interlocking to the fabric due, most likely, from the fabric being too dry when the EkoFill was brushed on. The old method (prior to 2017) was to brush EkoFill onto the fabric while the fabric was damp with clean, distilled water. The wet fabric allowed the EkoFill to interlock into the fabric, dry fabric results in the EkoFill simply sitting on the surface. Often, a large area was wet down all at once, than the EkoFill was applied. As the work progressed down the wing, the fabric started to dry out and parts of the surface did not take the EkoFill well (fabric dry at that location). When moisture gets inside the wing during heat/thaw cycles so common in AK spring weather, a blister will form. When the moisture goes away, the blister goes away. In 2017 we recommended sealing the weave with 3:1 EkoBond to distilled water before applying EkoFill as an alternative to wet fabric. That puts the EkoFill between two waterproof layers. The 3:1 EkoBond used to seal the weave bonded much better to fabric vs EkoFill on dry fabric. In our most recent version of our manual, we have removed wetting fabric as an option to eliminate this possibility from happening.

If, when peeling back a blister, you find EkoFill firmly attached to the fabric and only the top coat blistered, you have a different issue. One of two possibilities can exist. First, contaminants can cause the occasional blister. In your case, with large blisters and cracking, it may indicate the possibility that the paint froze prior to application as John stated.

Now, how to fix. If you can see through the fabric you need to address the issue. Blisters can be repaired by peeling away the paint and if bare fabric is present, clean and seal the weave with the EkoBond 3:1 followed by three coats of EkoFill followed by the top coat of EkoPoly Premium. For cracks on the stringers, there are a couple options. If tape is loose, you can remove it and apply new tapes. If it's too difficult to remove, patch over the tapes. Clean the area and use red scotch brite to scuff the area being patched. For a 2" tape, you could patch with a 3"tape. Use the lightweight tapes for the patch. The patch is glued down in the regular fashion and than EkoFill is applied over the tape on top of the glue than topcoat. All the repairs can be done using brush if you don't want to spray. If brushing, use a small cabinet roller followed by tipping with a brush. If you google "Roll and tipping for boat paint" you will see the process; works nicely with our paint.

Hope this helps some and gives you some options.

Marty

 

[mike mcs repair]

superflite offers some narrow pinked tapes that i like to use to patch over cracks in wide tapes on stringers and such... helps avoid pinks being in same area... then you build up primer coats and repaint...

cracks definitely will rot and become tears

https://superflite.com/collections/sf102-tapes

 

[ak49flyer]

Sounds like Stewart’s paint, unfortunately... Have seen this more often than not on planes covered in Stewart’s after a few years tied down outside up here... it’s a bummer because it sure was nice not to breathe MEK fumes when using their stuff, and I love how the glue works...

 

[adamgrenda]

We have figured out some possible causes for the blistering issues. When you peeled back a blister, what did you find underneath? If it was bare fabric than the EkoFill separated from the fabric. We've traced that to EkoFill not interlocking to the fabric due, most likely, from the fabric being too dry when the EkoFill was brushed on. The old method (prior to 2017) was to brush EkoFill onto the fabric while the fabric was damp with clean, distilled water. The wet fabric allowed the EkoFill to interlock into the fabric, dry fabric results in the EkoFill simply sitting on the surface. Often, a large area was wet down all at once, than the EkoFill was applied. As the work progressed down the wing, the fabric started to dry out and parts of the surface did not take the EkoFill well (fabric dry at that location). When moisture gets inside the wing during heat/thaw cycles so common in AK spring weather, a blister will form. When the moisture goes away, the blister goes away. In 2017 we recommended sealing the weave with 3:1 EkoBond to distilled water before applying EkoFill as an alternative to wet fabric. That puts the EkoFill between two waterproof layers. The 3:1 EkoBond used to seal the weave bonded much better to fabric vs EkoFill on dry fabric. In our most recent version of our manual, we have removed wetting fabric as an option to eliminate this possibility from happening.

If, when peeling back a blister, you find EkoFill firmly attached to the fabric and only the top coat blistered, you have a different issue. One of two possibilities can exist. First, contaminants can cause the occasional blister. In your case, with large blisters and cracking, it may indicate the possibility that the paint froze prior to application as John stated.

Now, how to fix. If you can see through the fabric you need to address the issue. Blisters can be repaired by peeling away the paint and if bare fabric is present, clean and seal the weave with the EkoBond 3:1 followed by three coats of EkoFill followed by the top coat of EkoPoly Premium. For cracks on the stringers, there are a couple options. If tape is loose, you can remove it and apply new tapes. If it's too difficult to remove, patch over the tapes. Clean the area and use red scotch brite to scuff the area being patched. For a 2" tape, you could patch with a 3"tape. Use the lightweight tapes for the patch. The patch is glued down in the regular fashion and than EkoFill is applied over the tape on top of the glue than topcoat. All the repairs can be done using brush if you don't want to spray. If brushing, use a small cabinet roller followed by tipping with a brush. If you google "Roll and tipping for boat paint" you will see the process; works nicely with our paint.

Hope this helps some and gives you some options.

Marty

Thank you that helps a lot. Nothing comes down to the fabric. The blisters and cracks all show some silver when I look through top coat. Not sure if it froze I doubt it but not positive. I’ll check out the YouTube and get some tapes on order.

 

[adamgrenda]

Thanks mike. That sounds like a good option.

 

[Hardtailjohn]

Sounds like Stewart’s paint, unfortunately... Have seen this more often than not on planes covered in Stewart’s after a few years tied down outside up here... it’s a bummer because it sure was nice not to breathe MEK fumes when using their stuff, and I love how the glue works...

And it's not a paint problem as stated above in Marty's post. Originally, we sealed the fabric with Ecobond and never saw a problem. They've gone back to that procedure. I'm not sure just why the procedure was changed, as I wasn't involved with the company at that time.
John

 

[Hardtailjohn]

Thank you that helps a lot. Nothing comes down to the fabric. The blisters and cracks all show some silver when I look through top coat. Not sure if it froze I doubt it but not positive. I’ll check out the YouTube and get some tapes on order.

I'd love to see some pictures of what's below the blistering paint if at all possible. Thanks!
John

 

[Marty57]

I'd love to see some pictures of what's below the blistering paint if at all possible. Thanks!
John

Adam is sending pictures my way, we will figure this out. Anytime there are issues like this that come up, we want to know so we can figure out the the causes. Alaska is a unique environment and we are very concerned with problems that may come up. Hope the weather is good to me in a couple weeks when I head up your way.
Marty

 

[Andy Stewart Systems]

Adam,

I just wanted to chime in here and let you know that I'm following this thread now and will stay in touch with John and Marty and see what we can learn about this situation and what we can do to help. I am aware that some of our first generation paint would show some blisters in that environment. The new generation paint is much better, but aside from that I think the bigger issue was the process of sealing the weave with EkoFill rather than EkoBond as Marty has explained. It's also possible that there was a deviation in the process as well. For example, on scenario that can cause these symptoms is spraying the EkoFill or paint in conditions that are too cold or damp. EkoFill needs to fully dry before painting to get good adhesion. It's also important that the EkoFill is sanded prior to top coating. Skipping that step can reduce adhesion. So there are several possibilities as to the cause. I am very curious about the cracks you are describing though. That is something that we really don't see with even our first generation topcoat. Unless perhaps the blisters have created an area that can flutter in the airflow and cause that? I would like to take a look at that when I'm up there in May and see what we can determine is happening. In any case, I think it would be prudent to take some steps now to preserve the fabric going forward. If the EkoFill is in good condition as you are describing, then all we need to do is scuff sand it and touch up some the affected areas and shoot over it with our new generation topcoat. You could also roll it if you are not as concerned with the appearance and would rather not spray. Please contact us directly and we will help you with this. You can email me at andy@stewartsystems.aero, or my cell phone is 740-616-0457. If anyone has any in service issues with our products, please let us know directly. We can only make improvements if we know about any issues and can get enough information to determine the cause. We are always looking for ways to improve! The Alaska environment is a tough one for sure, but I am confident that if applied properly, our system will hold up as well or better than any of them even in that environment. Also, for anyone in Alaska, please stop by the booth at the Airmen show and ask any questions you have and give us feedback if there is anything we can do to make our system even better!

Andy Humphrey A&P/IA
Stewart Systems
Owner

 

[adamgrenda]

Adam,

I just wanted to chime in here and let you know that I'm following this thread now and will stay in touch with John and Marty and see what we can learn about this situation and what we can do to help. I am aware that some of our first generation paint would show some blisters in that environment. The new generation paint is much better, but aside from that I think the bigger issue was the process of sealing the weave with EkoFill rather than EkoBond as Marty has explained. It's also possible that there was a deviation in the process as well. For example, on scenario that can cause these symptoms is spraying the EkoFill or paint in conditions that are too cold or damp. EkoFill needs to fully dry before painting to get good adhesion. It's also important that the EkoFill is sanded prior to top coating. Skipping that step can reduce adhesion. So there are several possibilities as to the cause. I am very curious about the cracks you are describing though. That is something that we really don't see with even our first generation topcoat. Unless perhaps the blisters have created an area that can flutter in the airflow and cause that? I would like to take a look at that when I'm up there in May and see what we can determine is happening. In any case, I think it would be prudent to take some steps now to preserve the fabric going forward. If the EkoFill is in good condition as you are describing, then all we need to do is scuff sand it and touch up some the affected areas and shoot over it with our new generation topcoat. You could also roll it if you are not as concerned with the appearance and would rather not spray. Please contact us directly and we will help you with this. You can email me at andy@stewartsystems.aero, or my cell phone is 740-616-0457. If anyone has any in service issues with our products, please let us know directly. We can only make improvements if we know about any issues and can get enough information to determine the cause. We are always looking for ways to improve! The Alaska environment is a tough one for sure, but I am confident that if applied properly, our system will hold up as well or better than any of them even in that environment. Also, for anyone in Alaska, please stop by the booth at the Airmen show and ask any questions you have and give us feedback if there is anything we can do to make our system even better!

Andy Humphrey A&P/IA
Stewart Systems
Owner

Thank you for all the feedback and help. Taking photos tonight and will email them to you and Marty.

 

[Bearhawk Builder]

Andy, I saw someone mistakenly spray Ekocrylic on fabric and get those cracks, never seen cracks with Ekopoly back to 2005.
Dave

 

[Andy Stewart Systems]

That's what I have found as well. I did see one that was painted with EkoCrylic and after 5 years it was just starting to show some cracks in high stress areas. I have never seen EkoPoly or EkoPoly Premium get brittle at all. I have had people paint over solvent coatings with our paint and then complain because it cracked. LOL. Not much we can do about that... We had one case in Canada where a shipment of EkoPrime froze and was applied to an airplane and it did crack in the first year. That was the first time I am aware of that one of our primers froze and yet was still in a condition that could be applied through a gun. Normally it permanently turns into a brick. Since then we have been putting freeze indicators on all freezable shipments so that does not ever happen again. If it freezes in transit we replace it, no questions asked.

 

[CharlieN]

While this thread is going and covering any issues that might creep up, I am getting close to decision time on the plane I am building.
I am going with aluminum wings such that my plane will be fabric fuselage and controls.

Now the question, I am in Vermont and this plane will live outdoors. It will be in blazing sun for well the 30 or so days we get that, but it will be wet and cold. I will have sewn covers, I have been working with WeatherMAX fabric for them.

My mind was originally on Oratex but I am not sure that is what I want. Lack of colors and pricing are a concern.

So where does Stewart coating fit in. We seem to get our most sun when it is bitter cold so the plane might be frozen on one side and warm on the other.
Your thoughts on the durability of your current system under these nasty conditions.

 

[Andy Stewart Systems]

Charlie,

I think you will find that Stewart Systems will hold up very well if you follow the manual. Covers certainly help. One thing I would recommend in those conditions regardless of which system you use is the pre shrunk finish tapes on the ribs and longerons. That prevents the tapes from shrinking over time in the heat of the sun and exposing the fabric at the tape edges to UV. Also, make sure not to get stingy on the paint. If you apply the paint really thin it can reduce it's life span. Of course you don't want to go overboard with it either. When coatings get too thick the flexibility is reduced. Stewart Systems has been on the market for over 20 years now (previously called Aircraft Finishing Systems prior to 2005) and we have seen excellent durability. It is also significantly lighter than any of the solvent systems. Oratex does have us beat on weight by a very small margin though. I have to give them credit on that. But there is not enough difference for that to be the determining factor really. We also have really good primers for the metal portions of the aircraft, and you can use the same paint as the fabric on the metal. We do have a dedicated metal paint, but I would probably just use the EkoPoly on both rather than buy two products. Please let me know if you have any questions!

Thanks!
Andy

 

[Bearhawk Builder]

Charlie, FWIW. I’ve done 7 planes that live here and they’re all holding up well. All but one Pacer is hangared though, that one is outdoors all year and looks great after 4 years. I flew my Bearhawk for 9 years with zero issues. Andy gave me some numbers on weight per s/f but I forget, maybe he can post them but the system is lighter than most per s/f. Oratex has its issues too, fading, adhering tapes.
Not trying sell you, just my experience.

 

[CharlieN]

This is sounding good, better than I expected since I have not paid allot of attention to your system for years.
I am going to study quite a bit more but I will say it is looking like my fear of water base systems needs to be put behind me.
Not sure if I am going to get out to OSH this year, I usually do but that will be a good time to truly learn not to mention I will have parts ready for cover.

 

[Andy Stewart Systems]

If you can make it to Oshkosh or SNF we will have free workshops at both. I think you would find that very helpful. Just let me know if you have any questions. There is a wealth of information on our website. There is a full video series on how to cover and you can download the manual. It's all free.

Thanks!
Andy

 

[CharlieN]

Thank you Dave,
Yes I have been reading that Oratex has issues and that Lars just denies. The tape issues might be temperature during processing related but I am questioning that their system is all that fabulous. Not to mention the company offering colors in the light fabric but refusing to provide it in the heavier material.

 

[Bearhawk Builder]

I like Oratex too, it has its place. I’ve just noticed the tape issue and fading on some. The Bearhawk LSA demo plane for one. Happy to help if you go that route.

 

[Andy Stewart Systems]

I think it's important with any fabric system to recognize that a lot of it depends on the human factor of the person installing it. If there are flaws in the fabric covering, don't rush to blame the system. I know I don't appreciate it when an issue is found in our covering system and it is automatically assumed to be a flaw in the system and later we find out that there was a deviation in the process. So I'm not quick to judge a problem in another system. I also do not want to quickly dismiss an issue as human error when there may be more to it. Regardless of which system we are talking about, I think it's important to find out for sure what is going on and not make assumptions. Oratex is an interesting system and I think it has it's niche in the market. How well it will hold up will only be seen as time goes by. One thing for sure, if you want to cover an airplane without endangering your health, it comes down to two options. Stewart and Oratex.

Andy

 

[bob turner]

Here is a suggestion from an observer. I know my way around dope and Stits, but have only observed (as the supervising IA) the Stewart system.

I would recommend a prospective Stewart System user find someone who is really good, and who would agree to supervise the finish spraying of an entire wing or fuselage. Once you can do that, and get it to look really good, you can proceed with your own aircraft with confidence.

I know the system can produce a really good finish. I have yet to see an entire aircraft properly done with a gloss finish.

I have experience with minor repairs, and really like the way the Ekofill goes on. I don't spray anything with iso-cyanates in it, nor do I have the personality for precise measurements, so I am personally sticking to dope or Stits.

 

[algonquin]

I really like working with the system, but don’t consider myself to be a expert by any means. Here is a couple of pic’s of my StarDuster done with the Stewart’s system on the bottom wings.

 

[algonquin]

It’s being kept in a open front unseated hangar in Northern NY where the temps reg. Go into below zero in the winter and 80’s for a while in the summer and there haven’t been any problems.

 

[bob turner]

There is the guy you need to learn from. Tutorials and videos don't work - you have to successfully do an entire wing.

If you cannot do somebody else's wing, then before you cover the entire aircraft, finish a wing or fuselage to Algonquin's standard. Then you still have the option . . .

I have not tried shooting the finish coat on anything. I have watched. Painful.