preservative. It is used in the manufacture of other chemicals. Zinc methyl () is used in a number of organic syntheses. Zinc sulfide (ZnS) is used in luminescent pigments such as on the hands of clocks, X-ray and television screens, and luminous paints. Crystals of ZnS are used in lasers that operate in the mid-infrared part of the spectrum. Zinc sulfate is a chemical in dyes and pigments. Zinc pyrithione is used in antifouling paints. Zinc powder is sometimes used as a propellant in model rockets. When a compressed mixture of 70% zinc and 30% sulfur powder is ignited there is a violent chemical reaction. This produces zinc sulfide, together with large amounts of hot gas, heat, and light. Zinc sheet metal is used as a durable covering for roofs, walls, and countertops, the last often seen in bistros and oyster bars, and is known for the rustic look imparted by its surface oxidation in use to a blue-gray patina and susceptibility to scratching. , the most abundant isotope of zinc, is very susceptible to neutron activation, being transmuted into the highly radioactive , which has a half-life of 244 days and produces intense gamma radiation. Because of this, zinc oxide used in nuclear reactors as an anti-corrosion agent is depleted of before use, this is called depleted zinc oxide. For the same reason, zinc has been proposed as a salting material for nuclear weapons (cobalt is another, better-known salting material). A jacket of isotopically enriched would be irradiated by the intense high-energy neutron flux from an exploding thermonuclear weapon, forming a large amount of significantly increasing the radioactivity of the weapon's fallout. Such a weapon is not known to have ever been built, tested, or used. is used as a tracer to study how alloys that contain zinc wear out, or the path and the role of zinc in organisms. Zinc dithiocarbamate complexes are used as agricultural fungicides; these include Zineb, Metiram, Propineb and Ziram. Zinc naphthenate is used as wood preservative. Zinc in the form of ZDDP, is used as an anti-wear additive for metal parts in engine oil. Organic chemistry Organozinc chemistry is the science of compounds that contain carbon-zinc bonds, describing the physical properties, synthesis, and chemical reactions. Many organozinc compounds are important. Among important applications are The Frankland-Duppa Reaction in which an oxalate ester (ROCOCOOR) reacts with an alkyl halide R'X, zinc and hydrochloric acid