What kind of form liner is used to produce a dimpled surface?
Dimpled surfaces are usually prepared by precasting. The base of the form is covered with a layer of crushed stone or gravel and a sheet of polyethylene film laid over it. Aggregate of two inches or more in diameter is usually used. Steel is set in the form and the concrete placed over the polyethylene. The dimpled surface is visible when the form has been stripped and the panel tilted up.