Perfume interactions with product base

Interactions between the perfume oil and the plastic are possible. Fortunately the instances of such interactions are rare, but when they occur, most likely in water-based, oil-free products with high perfume levels such as gel or liquid air fresheners or rim blocks, they can be quite annoying, since they may lead to the leaking of containers, the clogging of valves, and so on. Esters are particularly likely to interact with the more commonly used plastics. The problem may sometimes be remedied by replacing any esters used as solvents in the perfume compound by dipropylene glycol and by formulating the perfume to provide the desired intensity at the lowest possible perfume level. Discoloration of white plastic is usually caused by the same perfume materials that cause discoloration in white soaps (see Chapter 16). 

Most of the time when a smfactant-based product comes into contact with human skin in normal usage conditions, it has previously passed through all the skin compatibility testing phases and is unlikely to induce observable signs of irritation. However, it is the perception of the product by the consumers that will make the product acceptable or unacceptable and is thus an important criteria to be evaluated by the manufacturer. Such a perception will depend on many different parameters, of which several are independent of the surfactants and their interaction with the surface of the skin (e.g., the aesthetics or the perfume... 

It is known that as soon as a perfume is incorporated into a product matrix, pronounced effects occur on some ingredients, those for which the microenvironmental interactions have changed significantly. Physicochemical interaction is a consideration no matter what the base, whereas chemical interactions only become really important in consumer products possessing a reactive challenge for fragrance, for example products with low or high pH (e.g. below 4, above 9), or redox power (e.g. cold wave hair products or laundry bleaches). (Chemical stability issues are elaborated in Chapter 9.)... 

In mass market products such as hair sprays or deodorants, synthetic ethanol has distinct advantages for the manufacturer since the consistency and purity of the product ensures minimum plant and process changes from batch to batch. In the smaller fine fragrance market, however, the interaction of fragrance components and fermentation ethanol impurities is part of the artistry of the perfumer. This effect is much slower, or in certain cases cannot be repeated, with synthetic ethanol as the base. Hence fermentation ethanol has traditionally been used for these products and is likely to continue to be used in the future. 

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