Lift strut question

[Bird]

I am pricing the struts and like from Alaska Airframes they say a lot of people want their struts powder coated.
I am not a fan of powder coating, and I'd like to hear from ya'll, thanks.
Bird

[M Towsley]

Re: Lift strut question

I researched this when I had an experimental and was contemplating doing this. I was told the heat can change the molecular makeup of the metal. Not something I would want done to a lift strut. Hopefully the engineers and those 'in-the-know will chime in with their opinions.

[Hank Jarrett]

Re: Lift strut question

The heat cure from powder coat shouldn't have any impact on steel but I wouldn't do it to an aluminum load bearing part. That said, I have painted a LOT of car and model parts with Hobby-Poxy epoxy and gotten just as good a finish and resistance to weather as the powder coat parts with NO heat cure. Works great for steel, aluminum, magnesium and composite.
The next item is that I have seen powder coat parts that have gotten tiny cracks in the finish. Water penetrated the crack and the part corroded under the finish with no external indications. As a personal choice I DO NOT use powder coating on my planes. I like to know what is going under the finish. I use an etching primer and spray a regular metal finish. I did paint my control wheels with epoxy paint (not powder coat).
Hank

[M Towsley]

Re: Lift strut question

Hank, the lift struts on my AirBike were aluminum hence the reason I left them the way they were.

[MNJoe]

Re: Lift strut question

Don't do it. The inside of the strut prior to welding most likely has oil residue inside it. The heat needed to cure the powder will cause the oil inside to boil and gas off

[astjp2]

Re: Lift strut question

Don't do it. The inside of the strut prior to welding most likely has oil residue inside it. The heat needed to cure the powder will cause the oil inside to boil and gas off

Struts are sealed, not a problem...but the powdercoating fades real bad in the sun.

[paulnuss]

Re: Lift strut question

I'm going to chime in with Hank here. The insidious part about powder coating is as mentioned, a small damage like a nick or scratch, and rust can propogate beneath the coating, spreading about undetected. A two-part epoxy primer on a well-prepared surface will serve better, in my opinion. Randolph's Epibond for example is a two-part white epoxy primer, that is also an etching primer. Adheres well to aluminum as well as steel. After curing is quite tough, you can hardly scratch it with a knife blade. The Rand-O-Plate version from the same manufacturer is green like zinc chromate primer, also a two-part, etches for adhesion, and very tough. Polyfiber has their versions of these primers also. I have seen Agplanes painted with these coatings, which need all the protection from corrosion they can get, and the coatings do the job.

[Hank Jarrett]

Re: Lift strut question

I did think of one more potential problem if your struts are sealed. The baking process would increase the pressure inside the strut. I doubt it would be an issue on a steel strut, but on an aluminum one combined with the reduced strength at the elevated temperature to cure the powder coat (aluminum looses a SIGNIFICANT part of it's strength at only 200* F!) you could deform or damage the strut. If it was mine I would just NOT use powder coat (and I don't).
I painted the wheels on an old sports car years ago with two part, room temp cure epoxy, and other than yellowing some they look great. I learned a great trick since then. Add a few drops of BLUE to the paint to keep it from going yellow. Not enough to actually "see" that it has blue in it, just enough to keep the original color bright. Seems to work on silver and white. Makes the color a little "colder", but isn't really noticeable.
Hank

[TimHicks]

Re: Lift strut question

For what it's worth, we have a automated powder-coat line here at work and we powder-coat steel Stair parts every day. The oven is set at 350°F. The handrails and Balusters are sealed (1.5" round tube with .090" wall) and they have no problems from the temperature change.
However, some customers want their stairs galvanized. So before we bring those stair to the place that does the galvanizing, we drill holes in all the sealed parts (to unseal them) because the hotter temperatures of that process (700° - 800°F) would burst the sealed tubes (that's what they tell us, I've never seen it first-hand).

[Bird]

Re: Lift strut question

Well I guess that solves the powder coat question, not gonna get it.
Thanks all