A contractor who wants to understand architectural concrete should begin by considering the various basic concrete finishes and the demands they place on the construction techniques needed for proper execution. By starting at this point, the builder is better able to understand the quality control requirements needed for architectural concrete. The as-cast finish is one that is accepted the way it appears when the forms are removed. Construction of large expanses of smooth as-cast surfaces should be approached with caution. As-cast projects have been more successful when they have utilized a heavy form texture, have been subdivided into smaller surface areas to control, or have been made with white cement. The as-cast, common, smooth gray concrete surface is one of the most difficult finishes to accomplish uniformly. The second primary finish category to be considered is abrasive blasted (generally known as sandblasted). This type of finish can be classified under four headings: brush blast, light blast, medium exposed aggregate and heavy exposed aggregate. The third is chemical retardation of surface set. Surface retarders applied to forms react to prevent the surface skin of the concrete from setting. Recent advancements have improved the control of setting by these products. The performance of a surface retarder will be influenced by the chemistry of the individual cements, mix characteristics, the temperature of the concrete mix, the ambient temperature, the characteristics of absorption of the forming material, the possible variation in application or composition of the retarder, and the possible buildup of a retarder on a form through reuse. Surprisingly, good results can be produced even with these variables involved. The fourth is mechanically fractured surfaces. Mechanically fractured surfaces are prepared by one of four methods: scaling, bushhammering, jackhammering or tooling. This type of surface is described as fractured because it is prepared by impacting the concrete surface with a tool and thereby mechanically removing part of it.