Here's how to determine if your cotton or silk fabric is all natural or if there are man-made polyester fibres present. For more info, please check out the full article at: https://so-sew-easy.com/tips-testing-fabric-content/ Please be careful if trying this at home. In the video, I've used relatively large samples so you can easily see what's happening. I'm also in a controlled environment and using fabrics I'm confident have been soaked in anything or that may be overly flammable. If you're doing this yourself, use small samples and be very careful. Adult supervision is essential.