Leaders and tippets are generally constructed of monofilament or fluorocarbon fishing line. PVDF is used for specialty monofilament fishing lines, sold as fluorocarbon replacements for nylon monofilament. Race waxes comprise a combination of fluorinated hydrocarbon waxes and fluorocarbon overlays. PTFE is one of the two fluorocarbon resins composed wholly of fluorine and carbon. The compounds of rod seals are nitrile rubber, Polyurethane, or Fluorocarbon Viton. Fluorocarbon polymers have recently become an alternative to nylon treble strings. Hexafluoroethane is a fluorocarbon counterpart to the hydrocarbon ethane. Certain alcohols readily give the corresponding fluorocarbon. The tail group can be a hydrocarbon, fluorocarbon, or a siloxane. In 1930 Thomas Midgley, Jr. discovered dichlorodifluoromethane, a chlorinated fluorocarbon (CFC) known as freon. It is commonly used when referring to any fluorocarbon refrigerants. Fluorocarbon liquids have medical applications as oxygen carriers. It is slightly soluble in isobutyl bromide and in fluorocarbon (CF). The line usually consist of 8-10 lb fluorocarbon or mono-filament. The fluorous domain is often a substituent intended to confer solubility in the fluorocarbon medium.