Cleary Gottlieb is representing Altana in connection with its $635 million acquisition of the rheology additives business of Rockwood Holdings Inc. Altana, based in Germany, is a global producer of innovative and environmentally compatible solutions for coating manufacturers, paint and plastics processors, the printing and cosmetic industries, and the electrical and electronics industry. Its BYK Additives & Instruments division is one of the world’s leading suppliers in the additives and measuring instrument sector. Additives are chemical substances which improve product properties, such as scratch resistance or surface gloss, and help optimize manufacturing processes. The purchase agreement was signed on July 26th and the transaction is expected to close in the fourth quarter of 2013.