The rubber industry in general, and tyre manufacturers in particular, are the largest users of zinc oxide, owing to its important chemical, physical and optical properties.

Since heat build-up is critical at the higher operating speeds of heavy-duty pneumatic tyres (as compared with solid rubber tyres) they carry high loadings of zinc oxide for heat conductivity, as well as for reinforcement.
The important role played by zinc oxide in the rubber industry is expressed in various processes:

• Activation
  
  In the curing process of natural rubber and most types of synthetic rubbers, the chemical reactivity of zinc oxide is utilised to activate the organic accelerator. The unreacted share of the zinc oxide remains available as a basic reserve to neutralise the sulphur bearing acidic decomposition products formed during vulcanisation. Adequate levels of zinc oxide distinctly contribute to chemical reinforcement, scorch control and resistance to heat aging and compression fatigue.
  
  
• Acceleration
  
  Zinc oxide serves as the accelerator with some types of elastomer. The cross-linking that it induces takes several forms. With some systems, zinc oxide serves as an effective co-accelerator in the vulcanisation process.
  
  
• Biochemical activity
  
  Zinc oxide is useful in the preservation of plantation latex, as it reacts with the enzyme responsible for decomposition. The oxide also inhibits the growth of fungi, such as mold and mildew.
  
  
• Dielectric strength
  
  In high voltage wire and cable insulation, zinc oxide improves the resistance to corona effects owing to its dielectric strength. At elevated operating temperatures it contributes to maintaining the physical properties of the rubber compound by neutralising the acidic decomposition product.
  
  
• Heat stabilisation
  
  Zinc oxide retards the devulcanisation of numerous types of rubber compounds operating at elevated temperatures.
  
  
• Latex gelation
  
  Zinc oxide is particularly effective in the gelation of the foam, with sufficient stability, as part of the production process of latex foam rubber products.
  
  
• Light stabilisation
  
  Zinc oxide's absorption of ultraviolet rays is exceptional among white pigments and extenders. It therefore serves as an effective stabiliser of white and tinted rubber compounds under prolonged exposure to the sun's destructive rays.
  
  
• Pigmentation
  
  Zinc oxide provides a high degree of whiteness and tinting strength for rubber products such as tyre sidewalls, sheeting and surgical gloves, owing to its high brightness, refractive index and optimum particle size.
  
  
• Reinforcement
  
  Zinc oxide provides reinforcement in natural rubber, as well as in some synthetic elastomers, such as polysulfides and chloroprenes. The degree of reinforcement appears to depend upon a combination of the oxide's particle size, with the finest size being the most effective; and the oxide's reactivity with the rubber.
  Under conditions characterised by rapid flexing or compression, zinc oxide also provides heat conduction to enable more rapid heat dissipation, thereby providing lower operating temperatures. Additionally, it imparts heat stabilisation by reacting with acidic decomposition products.
  
  
• Rubber - metal bonding
  
  In the bonding of rubber to brass, zinc oxide reacts with copper oxide on the brass surface, forming a tightly adhering zinc-copper salt.
  
  
• Tack retention
  
  One of the unique properties of zinc oxide is its ability to retain over many months of shelf -storage the tack of uncured rubber compounds for adhesive tapes. French process zinc oxides impart heat-aging resistance superior to that of American-process zinc oxides. The former type, being sulfur-free, has a higher pH and, thus, can neutralise more effectively the acidic decomposition products formed during aging. Moreover, the finer French-process zinc oxides prove superior to coarser grades in heat-aging resistance.
  

Zinc oxide imparts heat resistance and mechanical strength to acrylic composites. It also contributes to the formation and cure of epoxide resin. Adding zinc oxide to epoxy resins cured with aliphatic polyamines imparts higher tensile strength and water resistance.

Furthermore, zinc oxide imparts fire resistant properties to nylon fibres and moldings. It is also useful in the preparation of nylon polymers and in increasing their resistance. The formation of polyesters in the presence of zinc oxide imparts higher viscosity and other improvements. It reacts with unsaturated polyesters to form higher viscosity and a thixotropic body.

It improves the dye ability of polyester fibres. Zinc oxide mixtures stabilise polyethylene against aging and ultraviolet radiation. Zinc oxide increases the transparency of poly molding resin, and improves the color, tensile strength and vulcanisation properties of polyolefins. It also affects the thermal stabilisation of PVC, and imparts antistatic, fungi static and emulsion stability properties to vinyl polymers.

Applications in development for zinc oxide stabilised polypropylene and high density polyethylene include safety helmets, stadium seating, insulation, pallets, bags, fibre and filament, agricultural and recreational equipment

The glass and ceramics industry is also a major user of zinc oxide in glazes and enamels.

Zinc oxide tends to increase the chemical durability of silicate glass. It is used in phosphate glasses, chemically resistant glass wares, glass metal seals and certain fibre glass compositions. Zinc oxide is also used as a stabiliser for cadmium sulphide and cadmium selenide during heat treatment, allowing the glass to retain its yellow or red color.

Additionally, zinc oxide is extensively used in enamels. It regulates the expansion coefficient, improves glaze and texture and also enhances opacity and whiteness. Furthermore, it is widely used in porcelain enamel frits, and in glazes for pottery and sanitary ware.

Zinc oxide neutralises acid and possesses mild bactericidal properties; it is therefore an ideal component in body cream and antiseptic healing cream, helping reduce soreness and redness.

Additionally, zinc oxide is used in medical tapes and plasters, some toothpaste formulations and in dental cements.

No less importantly, zinc oxide is incorporated into dietary supplements and vitamin tablets as a source of zinc, which comprises an essential micronutrient for the human body.

Zinc oxide and its derivatives contribute to various hair and skin care cosmetic preparations, thanks to their optical and biochemical properties. In powders and creams, they protect the skin by absorbing the sun's harmful ultraviolet rays, and also promotes healing in ointments used to treat sunburn.

Simple zinc salts impart astringent and skin conditioning properties to creams; more complex salts provide fungi static properties that enhance the effectiveness of deodorants, soaps, and antidandruff products.

Zinc oxide is a component in many formulations of durables and protective paints. One of its exceptional features is its opacity to ultraviolet light in the finished coatings, which improves weatherability. The oxide is not discolored by sulphur compounds in the atmosphere, as occurs in some lead pigments. It also protects the paint film from mildew, enhances resistance to abrasion and neutralises the harmful acids formed by vehicle aging.

Zinc oxide, owing to its amphoteric nature, reacts with organic acids to form soaps that act as a dispersing agent.

Zinc metal powder (zinc dust) and zinc compounds have long been utilised for their anticorrosive properties in metal protective coatings, and presently comprise the basis of metal primers, such as zinc chromate primers.

Zinc dust - zinc oxide paints are especially useful as primers for new or weathered galvanised iron. Such surfaces are difficult to protect because their reactivity with organic coatings leads to brittleness and lack of adhesion. Zinc dust - zinc oxide paints, however, retain their flexibility and adherence on such surfaces for many years. Furthermore, they provide excellent protection to steel structures under normal atmospheric conditions, as well as to underwater steel surfaces (dams, the interior of fresh water tanks).

Zinc oxide comprises an essential ingredient in the "soft" type of ferromagnetic materials used for television, radio and telecommunication applications. Ferrites based on zinc oxide (as well as on nickel oxide and magnetite) are used as elements in many types of electronic devices.

• The antenna cores in portable and car radios are ferrites, to provide highly selective tuning.
• Television picture tubes constitute a major market for ferrites, particularly for use in fly back transformers and deflection yokes.
• In the field of communications, ferrites are extensively used in the filter inductors of telephone circuits, to permit precise inductance adjustment for the purpose of separating channels.
• Magnetic tape for recorders is improved by the use of a magnetite precipitated in the presence of zinc oxide.

• Fungi stat
  
  Zinc oxide is not a fungicide per se; it is a fungi stat, i.e., it inhibits the growth of fungi. It is added to fungicides to enhance their effectiveness in specific applications. Zinc oxide derivatives also promote the control of fungi in a variety of applications.
  
  
• Photocopying
  
  Some of the unique electronic properties of zinc oxide are distinctively utilised in the photocopying process: the photoconductivity and semiconductor properties of zinc oxide are increased through special heat and/or doping treatments (the addition of foreign elements). Additionally, the optical properties of zinc oxide are significantly modified to increase its absorption of visible light, in a process called sensitisation, which is generally carried out through addition to certain dyes, which are absorbed on the surface of the zinc oxide.
  
  Commercial zinc oxide for photocopying is generally produced from metallic zinc, rather than ore, to obtain a product of higher purity.
  
  
• Lubricants
  
  Zinc dithiophosphates, which are prepared by reacting zinc oxide with organic phosphates, are used in substantial quantities as additives to lubricating oils for automotive engines, to reduce oxidation corrosion and wear.
  
  Zinc oxide has been found to contribute special properties in many types of lubricants, such as extreme pressure lubricants, seizure resistant lubricants and greases; such greases are useful in the lubrication of food processing equipment.
  
  Additionally, zinc oxide also improves adhesion.
  
  
• Fire retardants
  
  Zinc oxides, along with boric acid and ammonia, comprise components in solutions used to fireproof textiles; water insoluble Zn Borate is deposited on the fibres.
  
  
• Batteries, fuel cells, photocells
  
  Zinc oxide is used in zinc-carbon dry cells, zinc-silver oxide batteries, nickel oxide-cadmium batteries and even in secondary batteries. In fuel cells, zinc oxide is used as electrode material, cathodic material and as a fuel element. In solar energy cells it can act as a photo catalyst.