The surface finish of concrete is a subject of frequent discussion, and rightly so, since few concrete jobs can win applause from the general public on the grounds of structural form alone, And yet, while contractors and architects realize that "beauty is only skin deep," the owner of a structure is inevitalby influenced by the immediate appearance of the material. Today, placing an attractive face of a concrete surface can be done in any number of ways. A cement-based paint- the first of the cement based coatings- appreared early in the history of concrete construction. Today cement-based paint has had a long and highly successful record of use both for interior and exterior exporsures of all types. A service life of six or more years is easily achieved, and in many locations the coating may still be in good condition after ten and more years. The paints are manufactured by grinding together a portland cement, usually white, with several other components. These include hydrated lime and various water repellents. A desired color is obtained by adding limeproof and sunlight-resistant pigments. The ratio of portland cement to other ingrediants is seldom less than 1 to 1, but may be as high as 9 to 1. The usual ratio is about 3 to 1. As synthetic resisn became availabe, coating maunfacturers attempted to develop a formulation that could minimize the application steps involved with the cement only coatings. The theory was initially based on developing a formulation in which the cement would be used promarily as a filler while th eplastic would act as the binder. The advantage foreseen here was that the resin should retard evaporation fro the water to ve retained for hydration. Thus wet curing would be totally unnecessary regardless of job conditions. The economic advantages are obvious. In effect, the resin, usually in the form of a water-emulsion acryllic or polyvinylacetate latex, can by seen to act as a glue to hold the cement particles together while uncured or partially cured. The addition of extra water, whether for curing or thinning, can in most cases be determental because it tends to break down the glue and reduce the effectiveness of the final coating. More recent research has now shown that the interaction betwwn the cement and the resis is actually much more complex than was first thought, with the resin doing far more than just holding the water to promote curing. The chemical reaction is still but little understood, but the result means that any latex-modified cement coating will have far better impact resistance, tensility, flexibility, abrasion resistance and other porperties than will a straight cement system. Although the plastic/cement combination coatings still have a wide field of application, interest in the all-plastic materials has picked up. This development follows the availability of the "new" plastics, so that today a coating may be based on either a polyester, epoxy or polyurethane resin.