The term tooling refers to several kinds of mechanical fracturing used to achieve a particular visual effect by removing part of the concrete surface. Methods of tooling include abrasive blasting, bushhammering, use of scaling hammers or point tools, and grinding and polishing. The process of producing tooled surfaces commences weeks or even months before the casting operation. The success of the whole process depends on the achievement of a level of consistency in all stages--commencing with the establishment of standards and proceeding through batching, mixing, handling, placement, compaction and curing, on down to the eventual operation of putting the tool to concrete. Of utmost importance is the initial achievement of sound, well compacted concrete.
A most important consideration for the designer is that all tooling techniques result in the removal of some quantity of the concrete. This results in a reduction of the specified and valuable cover of concrete over the reinforcing steel, which is so essential to the long-term durability of the structure. Allowance must be made in detail to compensate for the depth of concrete which will be removed by the tooling process.
Formwork for the production of concrete which is to be tooled must be of good quality. The sheathing materials must be sound, close jointed and supported, not only to resist the normal deflections but also to avoid the incidence of "flutter"--the vibration of a sheathing face which develops in sympathy with the applied compactive effort. Flutter, particularly at sheathing joints, results in a high intensity of fines at the concrete face.