Anti-skinning agents (or anti-oxidants) are mild inhibitors of oxidative drying and are often included in paints that dry by that mechanism, in order to improve stability in the can. They are usually fairly volatile and evaporate once the paint is applied.

Moisture scavengers are included to inhibit reaction between paint ingredients e.g. isocyanates or zinc or aluminum pigments and water, which may have, entered the paint during manufacture. Such a reaction might prematurely gel the coating in the container or produce gas under pressure. Calcium oxide has been recommended for zinc rich coatings.

Paints are susceptible to deterioration brought about by micro-organisms. These include particularly bacteria, yeasts and fungi. All these types or organism can cause deterioration of liquid paint in the can, but most reported incidents are caused by bacteria which can cause gassing, viscosity reduction and colour drift in latex paints. Sterilisation of equipment and the use of commercial biocides protect against a wide range of bacterial types.

Once the paint has been applied it is exposed to a wide variety of airborne spores of yeasts, fungi and algae, if they find nutrients in the paint or in the dirt or debris adhering to it, plus moist conditions.

As the mildew, mould and algae multiply, film damage eventually results, leading to loss of protective properties. To prevent this, fungicides and algicides are included in paint formulations. A range of complex organic and organometallic compounds (especially tin complexes) are effective.

Large numbers of plant and animal organisms can cause fouling of ships below the water line, these paints contain anti-fouling additives, which contain biocides which leak slowly from the film, often based on copper or tin compounds.

UV absorbers are a class of additives added to paints where a high degree of durability is required. Most organic polymers undergo chemical change when exposed to ultra-violet radiation (or visible radiation in some cases). These changes are often called photodegradation and results in a deterioration of the mechanical properties of the bulk polymer. For example, a drastic loss of elasticity, or conversion of a polymer film into a fine powder.

Photodegradation is initiated by small amounts of impurities present in the polymer (often left over from the polymerization process) which undergo auto-oxidisation (reaction with oxygen using excitation energy of UV light) to break the chemical bonds within the chain.

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Ultraviolet absorbers absorb the light energy and convert the low energy state molecule into a less stable, higher energy form, which reverts back to the more stable low energy form dissipating that energy as heat and preventing the UV from breaking the resin polymer bonds.

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