All dope and fabric systems use aluminum powder mixed with the finish to
block UV, which causes all fabric and dope to deteriorate. Dacron
"sails" as used on ultralights don't have UV protection, so they must be
changed every few years. The advantage of undoped dacron sails is
simplicity and weight savings.

Their are two main differences in dope and fabric systems: Flammability
of the finished covering system and toxicity and flammability of the
components. Polyfiber is fireproof. I've tried it, dacron fabric
finished with Polytone won't burn unless you hold a flame to it.
Polyfiber dopes and solvents are highly toxic and flammable however and
must be shipped as hazardous material at extra expense. Other covering
systems are non-toxic and non-hazardous, I don't know how flammable the
finished job is for them. The traditional butyrate and nitrate dope
systems are highly flammable, and nitrate dope as used in the early
Ceconite system is explosively flammable when cured.

Most of this information I got from the Ray Stitts polyfiber video and
manual, A&P school, and what I've tried out in the shop.

Adam Aulick wrote:
What are the relative advantages and disadvantages of "normal" modern
fabric coverings (doped and painted polyfiber) vs. the stitched,
zippered sailcloth coverings (dacron, others?) on many ultralights and
new LSA airplanes? How are the sailcloth coverings attached?

The Aventura 2-place homebuilt I saw at Oshkosh had dacron wing covering
that looked for all the world like it was held on largely by tension.


--
John Kimmel


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or that we are to stand by the President, right or wrong, is
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to the American public."

Theodore Roosevelt