Synthetic essence consists of a solution of synthetic vanillin in ethanol. These are called synthetic or artificial fibers. They can be either synthetic or natural chemical compounds. Neoprene resists degradation more than natural or synthetic rubber. Polypropylene costs less than most other synthetic fibers. Both synthetic and natural yarns can pill. Natural and synthetic down alternatives are marketed. Yarn can be made from a number of natural or synthetic fibers. They can be made with either synthetic or natural lipids. They are used in the production of synthetic rubber. Wool ignites at a higher temperature than cotton and some synthetic fibers. They were not the only ones to introduce blends of both natural and synthetic fibers. The sole was made of synthetic or reclaimed rubber. It is important industrially as a monomer in the production of synthetic rubber. They are a diverse array of recombinant, synthetic, and natural preparations.