THE finishing of automotive products with lacquer is still in the transition stage, according to the author. Sufficient time has not elapsed to provide an adequate background of experience which establishes principles and practices that fully meet the requirements of the production engineer. In other words, many of the things we think we know about lacquer finishes and lacquer undercoatings are either not true or are correct in part only.
The general function of a surfacer is to provide a smooth surface for the finishing coats. Inasmuch as the larger part of the material applied to provide such a surface must be cut away by sanding so as to bring the surface as a whole to the requisite smoothness, a satisfactory surfacer is one that can be applied with the minimum effort, can be sanded with the minimum amount of labor, and can be purchased cheaply, the reason being that most of it is carried away by the wash water during the sanding process. Ease of application and of sanding are essential characteristics of a good lacquer surfacer but, to the author's mind, the proper relation of the surfacer to the primer and to the finishing coats of lacquer enamel is the basic requisite.
To present a clear idea of the relation of a surfacer to the finishing system as a whole, the elements of former practices are reviewed. The author then discusses the basic relations which exist between the lacquer enamel and the surfacer. First, the surfacer must not absorb the lacquer enamel except to a very limited extent. Second, the lacquer enamel must adhere firmly to the surfacer. Some lacquer enamels contain so much oil and plasticizer that this is difficult to accomplish and many materials which otherwise would be advantageous in surfacers tend to reduce the adhesion of the enamel to the surfacer. It is, therefore, obvious that the composition of the surfacer and of the lacquer enamel should bear a very definite relation to each other.
In conclusion, the author says that, notwithstanding their higher cost and lower “building value,” lacquer surfacers have come to stay because of their quick-drying and easy-sanding qualities. The remarkable progress already made in the development of lacquer surfacers and the continued activity in improving and perfecting them justifies not only the close attention of the automotive engineer but also a definite share of his time and energy in adapting production operations to bring about the most successful usage of lacquer.
The discussion includes definitions of the terms used in connection with lacquer and answers to numerous questions relative to details of lacquer composition and application.