Polymers, as a group, are invaluable to man. Their origin can be traced as far back as the beginning of life. For example, the natural polymer, deoxyribonucleic acid (DNA), is an essential component of life itself. Another polymer, cellulose, which is the main structural component of plants, is one of the most plentiful of natural products. The last 100 years have witnessed rapid progress in polymer science and this has made possible the development of numerous commercially important synthetic polymers which have found wide ranging uses in such industries as textiles, paints, plastics and packaging. However, the application of polymeric materials as film coatings to solid dosage forms is still a relatively recent practice. Abbott Laboratories are reported to have pioneered the production of film-coated tablets on a commercial scale in 1954 (Munden et al., 1964). Since then, a number of works on film coating have steadily appeared in the