I just covered a small free flight wing (291/2") with Polyspan and am really impressed! It's light, strong, adds strength to the airframe, and doesn't cost an unreasonable amount. Try it, you'll like it. The only negative (for those not familiar with the smell of nitrate or butyrate dope, or whose wife is not familiar with said smells!!) is the smell of dope-paint dope, that is...

The smell is the best part!
it's why they call it dope..

Did it take many coats to seal completely?

I was about to place an order with modelresearchlabs.com and was wondering about polyspan over mylar. I read on another thread that using mylar under silkspan or tissue can make the number of coats of dope to seal be reduced so can wind up being lighter overall than just the tissue/silkspan.

The mylar is supposed to add 'poke hole thru' resistance, while the tissue/'span adds strengh.

If the polyspan only took a couple of coats to seal, then the mylar may be overkill if the poly is strong on it's own..

clint