The following chart illustrates many of the characteristics of synthetic fibers that are commonly used in twines. The requirements needed for a specific application will determine which fiber is best. Example: If the requirement is for a lightweight twine that floats and is resistant to mildew, then polypropylene or polyethylene will be best. If, on the other hand, a twine with high tensile strength is to be used underwater, then nylon or polyester will be best.