Polyfibre Aerothane and Ranthane - what's the difference?


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Well-Known Member
Jan 30, 2012
New Zealand
The health issues with the Polyurethanes are because of the isocynates in the hardener - isocyanates = cyanide poison.

It effects your cell's ability to transport electrons and oxygen - in other words your cells cant breath. This basically kills all of you at once, effecting the organs first, and yes it's cumulative - once it's inside you it either takes a long time to leave your body, or never leaves. As the cells die the isocyanates simply move to the neighboring cell and prevent it working etc. You can get them into your body from the spray mist, or by your skin contacting the mixed paint or hardener alone.

Exposure to cyanide even at low airborne concerntrations (a few hundred PPM) can kill you in minutes. My father had a license to use cyanide powder for poisoning/trapping vermin back in the day when these things were allowed... it's seriously nasty stuff.

Burning anything covered with or made of polyurethane also releases isocyanates (cyanide) so they should not be used inside the aircraft cabin, in case of fire.

Joe Fisher

Well-Known Member
Feb 10, 2007
Galesburg, KS South east Kansas
I prefer to use Ceconite fabric and Randolph dope. On the sheet metal I use zinc chromate for primer and Randolph Enamel. The enamel color and texture is a near perfect match for the dope. The finish is durable and light light weight.


Well-Known Member
HBA Supporter
Log Member
Jan 1, 2013
After painting about 15 aircraft in the past using both Aerothane and Ranthane, the Ranthane seems to have a little more pigment in some colors, and having sprayed both paints in Metalic Silver, Ranthane Metalic Silver is easier to get a even coat of metalic. I talk to someone that restores Stearmans for a living and he had the same problem and will only use Ranthane metalic Silver when a customer request a metalic Silver.
Before someone ask, yes I know enough to keep it stirred.
I use a Turbine HVLP system that will run 2 guns and 2 fresh air hoods . My daughter and I spray at the same time.

Dan Thomas

Well-Known Member
Sep 17, 2008
It is very common to put car paint over polyfiber in homebuilts and it use to be legal on certified until about 10 years ago.
Dont mix brands for the most part if you do Stewarts you have to be all in. The glue seems the only thing that you can mix. Champion is doing it on the new Citabrias and Decathlons.
I did the car-paint thing over fabric. It cracks easily, even with flexant. The flexant was designed for plastic bumpers, not fabric.

Poly-Fiber recommends using their urethane on metal. Their colors match with Poly-Tone exactly. The only difference will be the shine on the metal compared to the flatter finish on the fabric.