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Hess's Paint Film Defects. Their Causes and Cure
Progress in Organic Coatings, 8 (1980) 207 - 209 @ Elsevier Sequoia S.A., Lausanne - Printed in the Netherlands
207
Book Reviews
Hess’s Paint Film Defects. Their Causes and Cure Edited and revised by H. R. Hamburg and W. M. Morgans, Chapman Hall, London, 3rd edn., 1979; pp. 504, L 25.
and
There are not many problems which more urgently push a paint technologist to rapid solutions than paint defects. In this situation he is usually left alone with his empirical knowledge and the hope that measures taken from this will help. Unfortunately many paint defects still cannot be explained satisfactorily by scientific arguments. And sometimes these arguments, on critical consideration, are not always convincing quite apart from being generalizable. Appreciating the distance between speculation and truth in explaining paint defects in still too many cases, it is admirable that authors dare to write a book on this subject. Hess’s Paint Film Defects, which has been edited and revised by H. R. Hamburg and W. W. Morgans, is a unique book from both the difficult and extensive subject treated and its usefulness in serving as a first (or the last) haven of help in the arduous task of troubleshooting. In seven chapters, defects arising during storage and application, defects due to faults in liquid paints, defects related to film formation and to poor adhesion and defects developing in service are treated. The last of these chapters itself covers almost half of the volume. As a whole, 118 different types of paint defects are discussed. The relevant literature is cited, although sometimes not very comprehensively. The eighth and last chapter presents hazards in using paints, a matter of great topicality. With most of the defects discussed, remedies are also mentioned, which may be the more helpful the closer the presented example fits the actual case. Certainly these suggestions help to find some entrance into the problem and its solution. Excellent photographs, partly in colour, illustrate the various paint defects and aid comparison with the problem in question. A remarkably large subject index helps the reader quickly to find the special defect he is looking for. A book on such a large and often controversial subject makes it easy for a reviewer to find some weak or even wrong points. For example, the difference between low and high pressure polyethylene is not a consequence of different stereo chemistry but of the linear or branched structure (page 152). The decrease of viscosity observed in cellulose lacquers during storage (page 6) is a phenomenon due to a rather slow approach to the equilibrium condition of the solution. This process is often called ‘ripening’. One should prevent this by a more convenient dissolution technique rather than by choosing an ester with a higher initial viscosity, because in this case a
viscosity drop is expected to occur likewise. Brittleness and adhesion are not necessarily related to each other (page 157). A film may be brittle and none the less adhere well to the support, especially as a very thin layer. In this case cohesion and adhesion failure have to be discriminated. In this connection it should also be mentioned that the loss of adhesion may be caused by solvent accumulated at the film/support interface as a result of phase separation during film formation. Due, to interfacial diffusion under certain conditions permeability may initially increase with the pigment concentration and only later on decrease on approaching the critical pigment concentration (page 176). From more recent literature it is obvious that oxygen usually permeates through paint films significantly slower than water. It is therefore not “far more difficult to keep oxygen out from the metallic substrate” (page 213). Blistering of paint films accompanying corrosion is not due to the volume increase on converting ferrous sulphate to rust but is caused by osmotic forces (page 213). A relative humidity of 60% is not necessarily the lowest limit where corrosion occurs (page 214). This depends greatly on the special electrolyte present and on the temperature. These critical remarks do not diminish the usefulness of Hess’s Point Film Defects. It has no rival, and if it is critically used and with some understanding of the limitations in the cases described, it may really be a big help. W. Funke
Surface Contamination - Genesis, Detection and Control Edited by K. L. Mittal. Volume 1, 554 pp., illus., 1979, ISBN 0-30640176-2; volume 2, 548 pp., ilIus., 1979, ISBN 0-306-40177-O. Plenum Press, New York and London; $39.50 each or two volume set at $65.00. Technical surfaces, which must be protected by means of an organic coating, should at least be sufficiently clean, but have often to be specifically prepared as a substrate that provides for adequate adhesion of the paint film. This general and well-known rule can now be applied considerably better than it could some years ago, owing mostly to the amazing progress in the field of modem surface analytics. An overview of the state-of-the-art, as well as of the various practical problems which can already be solved by using these techniques, seemed in order at the present stage of development. It was given in remarkable variety and especially with adequate consideration of both theoretical and practical aspects within the program of the Fourth International Symposium on Contamination Control, held in Washington, D.C., on September 10 - 14,1978, under the sponsorship of the Institute of Environmental Sciences and the International Committee of Contamination Control Societies. The proceedings have now been made available to the technical community interested in this field, with its ramifications into many
207
Book Reviews
Hess’s Paint Film Defects. Their Causes and Cure Edited and revised by H. R. Hamburg and W. M. Morgans, Chapman Hall, London, 3rd edn., 1979; pp. 504, L 25.
and
There are not many problems which more urgently push a paint technologist to rapid solutions than paint defects. In this situation he is usually left alone with his empirical knowledge and the hope that measures taken from this will help. Unfortunately many paint defects still cannot be explained satisfactorily by scientific arguments. And sometimes these arguments, on critical consideration, are not always convincing quite apart from being generalizable. Appreciating the distance between speculation and truth in explaining paint defects in still too many cases, it is admirable that authors dare to write a book on this subject. Hess’s Paint Film Defects, which has been edited and revised by H. R. Hamburg and W. W. Morgans, is a unique book from both the difficult and extensive subject treated and its usefulness in serving as a first (or the last) haven of help in the arduous task of troubleshooting. In seven chapters, defects arising during storage and application, defects due to faults in liquid paints, defects related to film formation and to poor adhesion and defects developing in service are treated. The last of these chapters itself covers almost half of the volume. As a whole, 118 different types of paint defects are discussed. The relevant literature is cited, although sometimes not very comprehensively. The eighth and last chapter presents hazards in using paints, a matter of great topicality. With most of the defects discussed, remedies are also mentioned, which may be the more helpful the closer the presented example fits the actual case. Certainly these suggestions help to find some entrance into the problem and its solution. Excellent photographs, partly in colour, illustrate the various paint defects and aid comparison with the problem in question. A remarkably large subject index helps the reader quickly to find the special defect he is looking for. A book on such a large and often controversial subject makes it easy for a reviewer to find some weak or even wrong points. For example, the difference between low and high pressure polyethylene is not a consequence of different stereo chemistry but of the linear or branched structure (page 152). The decrease of viscosity observed in cellulose lacquers during storage (page 6) is a phenomenon due to a rather slow approach to the equilibrium condition of the solution. This process is often called ‘ripening’. One should prevent this by a more convenient dissolution technique rather than by choosing an ester with a higher initial viscosity, because in this case a
viscosity drop is expected to occur likewise. Brittleness and adhesion are not necessarily related to each other (page 157). A film may be brittle and none the less adhere well to the support, especially as a very thin layer. In this case cohesion and adhesion failure have to be discriminated. In this connection it should also be mentioned that the loss of adhesion may be caused by solvent accumulated at the film/support interface as a result of phase separation during film formation. Due, to interfacial diffusion under certain conditions permeability may initially increase with the pigment concentration and only later on decrease on approaching the critical pigment concentration (page 176). From more recent literature it is obvious that oxygen usually permeates through paint films significantly slower than water. It is therefore not “far more difficult to keep oxygen out from the metallic substrate” (page 213). Blistering of paint films accompanying corrosion is not due to the volume increase on converting ferrous sulphate to rust but is caused by osmotic forces (page 213). A relative humidity of 60% is not necessarily the lowest limit where corrosion occurs (page 214). This depends greatly on the special electrolyte present and on the temperature. These critical remarks do not diminish the usefulness of Hess’s Point Film Defects. It has no rival, and if it is critically used and with some understanding of the limitations in the cases described, it may really be a big help. W. Funke
Surface Contamination - Genesis, Detection and Control Edited by K. L. Mittal. Volume 1, 554 pp., illus., 1979, ISBN 0-30640176-2; volume 2, 548 pp., ilIus., 1979, ISBN 0-306-40177-O. Plenum Press, New York and London; $39.50 each or two volume set at $65.00. Technical surfaces, which must be protected by means of an organic coating, should at least be sufficiently clean, but have often to be specifically prepared as a substrate that provides for adequate adhesion of the paint film. This general and well-known rule can now be applied considerably better than it could some years ago, owing mostly to the amazing progress in the field of modem surface analytics. An overview of the state-of-the-art, as well as of the various practical problems which can already be solved by using these techniques, seemed in order at the present stage of development. It was given in remarkable variety and especially with adequate consideration of both theoretical and practical aspects within the program of the Fourth International Symposium on Contamination Control, held in Washington, D.C., on September 10 - 14,1978, under the sponsorship of the Institute of Environmental Sciences and the International Committee of Contamination Control Societies. The proceedings have now been made available to the technical community interested in this field, with its ramifications into many