So far I and others locally are Stewart's supporters. Those with previous issues now probably recognize the need for proper preparation like adequate drying and no spraying of aerosols (spray lubes or paints) nearby during the layup.

Gary

The only thing I've seen that has given me pause with the Stewart's process is a Highlander that had a fuel tank leak. He was running non-ethanol 92 auto gas, and it really yellowed the white Stewart's paint.

I'm not sure if that's par for the course with Stewart's and auto gas, or what? @hardtail john?

I remember reading where the additives is auto gas can be damaging to Stewart’s, it was recommended to paint the fuel tank bay to combat this issue.

Any ag planes using Stewart’s? I’m about to cover some tail feathers off a Cat and would like to try Stewart’s, but I’m worried how it will hold up in our environment. Don’t wanna be a guinea pig.

Zzz wrote:The only thing I've seen that has given me pause with the Stewart's process is a Highlander that had a fuel tank leak. He was running non-ethanol 92 auto gas, and it really yellowed the white Stewart's paint.

I'm not sure if that's par for the course with Stewart's and auto gas, or what? @hardtail john?

Man, in my experience, auto gas will stain the living crap out of anything painted white. And, hard to impossible to remove. There are some "interesting" additives in that stuff, apparently.

Now, whether that's cosmetic damage, or structural.....?

MTV

Zzz wrote:The only thing I've seen that has given me pause with the Stewart's process is a Highlander that had a fuel tank leak. He was running non-ethanol 92 auto gas, and it really yellowed the white Stewart's paint.

I'm not sure if that's par for the course with Stewart's and auto gas, or what? @hardtail john?

Stewarts isn't a fan if moGas. But I've been told the same as centerhillag. Paint the inside of the fuel bay if using mogas to seal the I side of the fabric. Not an option with all planes, but if possible its smart. FWIW, ive seen polyfiber wrecked because of leaky tanks as well, with avgas.

MTV is exactly right! Mogas has some awful stuff in it occasionally!! It will kill any topcoat. We do recommend painting the inside of the tank bay, and in the new manual updates we are working on right now, we'll add some other easier ways to deal with it.
There are ag operators using it. The Polyurethane topcoat is as good as anything I've ever seen and better than most in my opinion.
Thanks Dane, I try. I've screwed up enough things that I usually have had to figure out a way out, so glad to help others!
John

Couple thoughts:

No doubt a high quality cover job would cost quite a bit of money; covering is labor intensive and time consuming. My dad and I covered our BH with no prior experience but we had the poor Stewart systems tech support guy on speed dial. I’m deeply indebted to him. It cost us about $3k in materials and about a week of work. Our cover job is far from professional but it looks pretty good and is airworthy. With a willing mechanic you could save a significant amount of money and do the labor intensive stuff yourself.

Looking back I wish we would have taken the time to haul our plane to hardtrailjohns’ shop. There we would have received a full discourse on covering and ended up with a perfect cover/paint job.

Second thought: The day after we sprayed the finish coat on our fuselage we learned about a reinforcement to the tail post and decided we wanted to do it. We tried several different chemicals to remove the paint so we could cut away the fabric around the tail post. Only thing that worked was real MEK and it only sorta worked. This was with paint that had not yet fully cured. I don’t know about the chemicals used in Ag but I’d guess that Stewart’s would hold up as good as anything. Probably better.

I suspect it's the underside of the cover job that's most susceptible to quick damage from fuel and solvents. I clean air contaminants (fire wood and furnace smoke is bad) from my Stits Polytone with naphtha or charcoal lighter fluid per Stits' recommendations. Alcohol (isopropyl) will work on it more. Autofuel can soften it in time.

Aerothane and Stewart's top coat is tough and seems resistant to most fuels and solvents from what little experience I've had.

Gary

One thing I did want to mention in this post for the original poster, and meant to say before but just got sidetracked.
One BIG advantage to a dope finish or Polytone is that you can rejuvinate them as they need it. Do this before they show cracks, and they will last a lot longer. Once they are cracked, they need repaired, then rejuvinated. This is definitely an advantage in my eyes and can prolong the life of the cover significantly.
None of the polyurethane finishes can be rejuvinated. That being said, they last longer to start with, so the need to rejuvinate isn't there, except in rare situations.
HOWEVER..... I no longer will do any dope finishes in my shop. The reason being that I've lost 2 acquaintances from a post crash fire, when they had non life threatening injuries to start with.
Polyfiber (both Polytone and Aerothane), Ranthane, Stewarts, and I'm pretty sure a few others ( I haven't personally tested any others, so wont attest to their properties) will not support combustion. To me, that's a big deal. Your mileage may vary.
Thanks for the vote of confidence, Whee! We sure would have had some fun with you up here!!! I think you did just fine though!!
John