| abstract |
A non-aqueous composition comprising a halochromic dye, a fragrance material, a non-volatile base or acid, and a highly polar, low volatile solvent is disclosed. The composition changes its colour when the predominant part of the fragrance material has evaporated over time. The preferred composition comprises Bromocresol Green as the dye, triethanolamine as the non-volatile base, dipropylenglycole as the solvent, and a fragrance composition. Also claimed is an air-freshener device in which a composition of the present invention is absorbed or adsorbed in a material selected from paper, textiles, felt-type materials, wovens and non-wovens, glass fibre filters and crystals. |