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An important event in the science of polymer chemistry has been announced recently by the DuPont Company, which announced a new process for making polymers by what is called group transfer polymerization (GTP). Interestingly enough, this important scientific advance has practical ramifications in the area of automotive coatings. There are today three important ways to make polymers. The first is by initiation of the polymerization with free radicals. The second is by initiation with ions, either cations or anions. The third method is by use of the well‐known Ziegler‐Natta catalysis. It is by this latter technique that high density polyethylene, polypropylene, linear low density polyethylene and a number of other important polymers are made.

Just as the flow of new proprietary products has decreased so is there a lessening in announcements of new raw materials. More and more, paint companies are making do with the raw materials that they have known for the last few years. This is not to say that the coatings industry does not have an extensive armoury from which to formulate new products. It does mean however that the ingenuity of the coatings chemist will be tested as he tries to meet the exacting demands of industry without a continual flow of new polymeric materials or the other components he needs for protective coating formulation. It is an interesting point that the last three years have not produced a truly new polymer which could be useful for coatings. On the other hand numerous modifications have been proposed which are intended to facilitate the formulation of water‐borne coatings and other materials which are nonpolluting and nontoxic.

The paint industry is always intrigued by speciality coatings. Literally thousands of paint formulations have been devised over the years with highly specialized and very frequently intriguing functions. In this latter category is a process described in Japanese patent 19,790 (1971) for painting polka dots upon sheet metal. How often the need for such technology might arise in the life of the average paint chemist is, of course, a moot question. But some comfort can no doubt be drawn from the fact that this unique methodology exists!

When this Review was started in the early fifties, one would have been hard pressed to find articles in the paint literature about pollution. Some articles appeared about safety and toxicity and, of course, pollution was recognized as an undesirable factor. But that pollution, toxicity, and safety would one day occupy a major role in the activities of industry was hardly predictable.

HIGH SOLIDS COATINGS Review Articles Without question, the major motivation for high solids coatings is government regulations. An interesting article which summarises what the coatings industry has done in order to meet air pollution regulations in the United States has been provided by Burger (Metal Finishing, July, 1982, p. 59). His list includes, in addition to high build and solventless coatings, electrodeposition, electrostatic powder coatings, Rule 66—acceptable solvent‐based coatings, and water‐borne coatings. Air pollution results not only from solvents but from the particulates released during surface preparation. Pollution due to surface preparation has been alleviated by the use of white water sandblasting, centrifugal and rotary blast cleaning blast cleaning with carbon dioxide pellets, improved ventilation air filters and safety equipment, plasma arc and laser cleaning, sonic cleaning, special chemical cleaning, and surface preparation and vacuum blasting. In addition, solvent recovery units have been utilised extensively in industrial coatings.

Nineteen hundred and seventy‐three saw the introduction of a variety of new proprietary products resulting, for the most part, from technology which is well familiar to the paint industry. The continued introduction of proprietary products is one measure of the health of the industry. There are, of course, many other yardsticks but on this basis it is safe to say that the industry is a vigorous one and is trying continually to achieve improvements which will make its products more useful and more functional.

Specialty Maintenance Paints. Highly advanced technology presents numerous opportunities for specialized maintenance paints. Some of these which have been offered recently will be described here.

Appleby and Mayne [Journal of the Oil & Colour Chemists' Association, 59, 2 (1976) p.69] have studied the relative protection provided by red lead to linseed oil, tung oil, oiticia oil and a long oil ,alkyd varnish. The degradation products have been identified by gas liquid chromatography, the corrosion properties on mild steel having been compared by partial immersion tests. Linseed oil proved to be the most protective material; oiticia oil was next and the alkyd last. The authors concluded that lead azelate formed in the linseed oil paint and had strong corrosion‐inhibiting properties. These same authors [British Corrosion Journal, 10, 4 (1975) p. 201] have studied the effect of cations on the auto‐oxidation of linseed oil fatty acids and the inhibitive properties of the degradation products. Again, they found that alkaline earth azelates might be useful corrosion‐inhibiting additives for non‐soap forming vehicles.

The most important problem the maintenance paint industry is confronted with yearly is corrosion. Maintenance painting is that part of the industry which provides room temperature cure paints with corrosion protection. These paints are used on metal, wood, and other substrates in plants, factories, pipelines, etc. where corrosion is apt to occur. Paints that serve in the maintenance area are sophisticated coatings based on vinyls, epoxys, urethanes, zinc rich materials and a host of other vehicles each of which plays a special role in protecting a substrate and in fighting corrosion.

Closely related to coatings are the patching and caulking materials which are important in proper maintenance of many structures. A new product known as Roof and Gutter Patch has been introduced by Southern Protective Products Company [P.O. Box 10888, Atlanta, GA 30310]. The product is based on butyl rubber and can seal joints, seams, and cracks in galvanised metal, aluminium, or vinyl‐clad gutters, troughs, and downspouts. It can also be used to repair roofing, flashing, and chimneys, and to reseal asphalt shingles. The product is said to maintain a tough, pliable bond for years and may be coated with either oil or latex paints.