Davide,

Velvet was never used on any CS flags that I have ever seen and I have seen a lot of them in over 25 years of research. Early war flags were made of silk, especially company level colors.

Later war flags, from Spring of 1862 onwards, were made of imported Wool Bunting. This was a very durable material brought in from England during the war. Both sides used it; the Federals only for their larger post, garrison and storm flags. Federal units colors remained silk during the war.

I hope this helps.

Greg Biggs