Lighting colour effect

Colour change Caused by exposure to light, the effect is greatest with hardwoods and is important in furniture, panelling and joinery any masked areas become blemishes. Strong sunshine bleaches most woods to a common brown colour. 

The most effective antioxidants for light coloured rubber compounds are the hindered bisphenols, but these offer little ozone and flex cracking resistance. 

Bisphenol derivatives show very good antioxidant activity and are the best materials for light coloured articles. Selected materials are FDA approved. These derivatives have low volatility and no effect on cure rate and do not give a bloom. A slight pink discoloration can occur after prolonged exposure to light in white or light coloured products. 

Iridescence in many of the fabrics that are available commercially is basically a two-colour effect due to the absorption of light from dyes in two differently coloured yam bundles, constructed in such a way that the reflected light comes from one particular bundle in one direction and from another in a different direction. Whilst this is not truly iridescence it is a useful effect, but the process is very limiting on the construction of the fabric. 

Where indigo and another dyestuff are present, it is sometimes necessary —besides estimating the indigo—to determine the relative colour effects due to the indigo and to the other colouring matter,1 and also to identify the latter and measure its fastness to light, washing, etc... 

During the period between the first and second world wars a plastics business was developed based upon rennet casein from cow s milk, from soya beans or other pulses the reaction with formaldehyde gave a rigid plastic material which could be produced in light colours, mottle and pearlescent effects, and was capable of being machined and polished to a high gloss. 

Afterfixing agent for improving the wet fastness properties of polyamide fibres dyed or printed with acid dyes. The light colour of this compound results in minimal effect on bright shades or white grounds of printed fabrics. Used to reserve polyamide when dyeing cotton/polyamide blends with direct dyes. 

A 58-year-old woman, with a history of chronic stable hepatitis C infection, was given thahdomide 200 mg/day for end-stage plasma cell leukemia (77). Within 1 week she developed jaundice, light-coloured stools, and marked rises in serum transaminases, which had been stable before the introduction of thalidomide. The jaundice resolved promptly on withdrawal of all drugs other drugs besides thalidomide that might have been implicated were reintroduced without ill effects. 

Citrus oil is a natural flavouring derived from citrus peel that has a colouring effect with a light yellow shade. 

The polyphenols and tannins in hardwoods largely contribute to wood colour, particularly heartwood colour, and in earlier times some hardwoods were sought after for dyestuffs. Colour change is undesirable with darker timbers that are rich in extractives, where they are to be used for joinery or furniture. With light-coloured woods such as pines the effect of ultraviolet light is complex (Hon, 1991). Some pines can have very pale sapwood. Unfortunately the attractive white surface can yellow where directly exposed to sunlight (Sinclair and Vincent, 1964). 

This group of materials offers the most problems in colour measurement terms, because of the influence of translucency and light trapping effects on the colour results. Baardseth et al. (1988) reported that the prediction index for yam colour measurements was the least precise in the red/green parameter than for all the other foods evaluated in the paper, such as mashed potato, raw potato and raw cauliflower. The authors suggested that homogeneity was a key factor in obtaining the most precise prediction index, and that in the case of yams, therefore, variations in the fruit pieces may have been a factor in the loss of precision. 

A comprehensive survey of the solasodine content of 85 native Australian Solanum species has been published. Several studies have appeared which describe the changes in distribution and concentration of solasodine during the Ufe cycle of S. laciniatum. The effects of light colour on the solasodine content of 5. laciniatum and on the solasodine content of clones of 5. dulcamara have been studied the effect of ecological factors on alkaloid production by these two species has also been investigated. The solasodine contents of developing berries,fruits, and seed callus of S. khasianum have been reported. 

Saytex BT-93 is also non-toxic and does not bioconcentrate. It meets the German Dioxin Rule and has excellent recycling properties. It is effective at low loadings so not affecting compound properties with again high UV stability. Saytex BT-93W is particularly useful in light coloured formulations. 

There are also cost advantages for moulders of polyamide parts, which come from the high bromine content and FR efficiency of FR-1808, and the processing aid effect during moulding that reduces cycle times and lowers power consumption. Production of thin-walled parts results in a reduction of weight and light coloured materials can be achieved if desired. 

Antistatic agents such as carbon black, metal powders, surfactants or other hydrophilic substances can be blended with polymer matrices to dissipate electronic charge. However, carbon black makes materials black, so if a light colour is required, carbon black cannot be used. If some low-MW antistatic agents like surfactant are used, their antistatic effect is brought about by the equilibrimn moisture adsorbed on the surfactant, so sufficient antistatic effect is not achieved under low humidity. Furthermore, the surfactant is removed by rubbing or washing back and forth, and the antistatic effect disappears easily [54]. 

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