I have been through the gammit with covering techniques, materials, and application. I started with tissue and dope, went to silkspan and dope, went to silk and dope, went to Monocote, and then Ultracote. Recently I have found that Monokote and Ultracote have changed their formulas and their coverings have shown regression in quality and adhesion. I am a firm believer in a balsa prep such as Balsarite.

Sig Koverall is a superior material but my all time favorite is still silk and dope. Ounce for ounce, silk is still the strongest fabric compared to all others.
I have covered many of my birds with glass and resin. I have a new proposal that I believe will save considerable weight but still retain strength and that is....
.06 ounce poly cloth (SIG Koverall) and nitrate dope. I realize nitrate is not fuel proof but my final primer and paint will be a 2 part urethane and poly is shrinkable with heat.

There is one other new method on the market and that is a water based finish called EZE-Kote sold by Horizon Hobbies but I am not going that route since I have reservations about warpage using water based materails.