Anionic inverse emulsion thickener. Imparts a long stringy flow to a wide variety of aqueous and non-aqueous compositions and is effective over a wide pH range. Low viscosity liquid which gives instantaneous thickening on direct mixing into the composition. The polymer is already in solution (as the sodium salt) and does not require any other additives to promote thickening e.g. alkali, surfactant etc. APEO free.