I mentioned in a previous post that I had made a skirt from a fabric of unknown composition. Since I wanted to list it in my Etsy shop I really wanted to know what it was made of. A little Googling led me to this wonderful site. I followed their directions and was delighted to get fairly definitive results.
They point out that fibre blends are often simply constructed of one material as warp and the other as weft. So I separated the two in my sample, and sure enough the first one burned and charred, gave off an odour of burning paper, and left soft black ash; indicating linen or mercerised cotton. I already suspected linen, and the fibres are matt rather than shiny. So linen in one direction.
I couldn't see an obvious difference between the two directions of fibre, but I decided to burn the second set for completeness. Well I'm glad I did, because the second set burned and melted, gave off an odour of vinegar, and left hard black ash; indicating acetate or triacetate.
It was rather exciting to be able to get so much information from such a simple test.