Some slight modifications have been made to the Rit Dye Formula due to the lack of availability of some dye substances. With the new formulation, Rit will continue to dye most fabrics and materials, just as before. The only fabrics it will not dye are 100% acetate, polyester, acrylic and spandex. It will also not dye certain plastics made out of polycarbonates, such as golf discs and components of RC Cars. However, it will dye nylon-based plastics such as buttons and golf balls. It's always best to test the dye on your material first to see if you are satisfied. All the Rit liquid dyes are now packaged with this new formula. The powder dyes are being converted gradually to this new formula. Colors that have been converted are: Royal Blue, Petal Pink, Fuchsia, Cherry Red, and Pearl Grey. We will be posting more information about the new Rit formulation in upcoming blogs. We will send you two courtesy vouchers. You would want to make sure the package does not say ND which is the newer version of the product.