These bleaches require careful use to avoid a brittle and weak final product. Reductive bleaches do not degrade the coloured compounds, but instead chemically modify them into colourless compounds. These bleaches do less damage to the plant structure, but when used alone cause the plant material to yellow with age, which is a major drawback. The amount of water, cellulose, waxes, oils and pigments in plant material affects the bleaching treatment. Water Up to 97 per cent of most plants is water.
Water is present in all parts of the plant and in some cases is responsible for structural support.
In these cases, such as the Geraldton wax flower, bleaching is not successful. Cellulose The second most abundant material in a plant is cellulose - the 'plant skeleton'. The cellulose fibres which provide structure are embedded in coloured lignin. The fibres may be damaged if the bleaching conditions are too severe. An ideal bleach destroys everything else but leaves the cellulose intact.