Rick Campbell, president, Trust Chem USA, announced that Andrew Blum has joined his staff.      Mr. Blum has nearly 50 years experience in the pigments and pigments consuming industries. After holding various positions with ink, paint and dispersion firms, he joined American Hoechst, where he eventually became director for the North American pigments business for Hoechst Celanese. After Hoechst sold its industrial units to Clariant, Mr. Blum joined Roma Color/EC Pigments, first as vice presid...