The use of precast concrete is a very fast-growing segment of today's building industry and tilt-up panels incorporating the use of stone as a facing material are becoming a conventional method of construction. New casting techniques have recently been perfected that enable the tilt-up stone caster to fabricate relatively large numbers of panels. A greater variety of rock forms, textures, and colors can now be job-cast than can be cast by the plant precaster or laid by the stone mason. The tilt-up stone fabricator uses stone and rock materials from several sources; the masonry stone producer, the casting plant stone aggregates producer, the cut stone producer; he also uses certain materials from the sand and gravel producer. Most of all, the fabricator uses stone that has been quarried and produced just for him and his particular use. High quality stone such as quartzite, which is too hard to cut by the cut stone quarrier and too hard to shape and lay in mortar by the stone mason, can now be cast in beautiful tilt-up stone walls. The architect, upon quarry confirmation, specifies the stone selected; it is then quarried and, when ordered by the stone fabricator, shipped directly to the job. This provides a saving in quarry and handling costs. Grouting is an important step in the casting operation. It improves the bond of cement to rock and upgrades the quality of the rock facing work. It also protects the facing materials from damage during the placement of the reinforcing steel and concrete. It should be sprayed on the facing by means of a specially designed grout pump. It should hold its moisture and bonding properties despite sun and wind and yet harden enough in a day to allow carpenters, steel workers and finishers to complete their installations and concrete work. Certain types of panels cannot be cast without the sprayed on bonding grout. The architect should specify a plastic 3 or 4 inch slump concrete mix having a three-fourths to a 1 inch maximum rock size in the mix. This mix must be carefully placed without excessive transporting in the forms and carefully vibrated using a 1 and three-eighths of an inch square head vibrator, following good vibration practices. Improper vibration and high slump mixes have ruined more tilt-up rock jobs than all other shortcomings combined.