Any masonry ornamentation that can be carved in natural stone probably can be formed in cast stone. A type of architectural precast concrete, cast stone is manufactured to simulate natural cut stone. It is used in masonry work mostly as ornamentation and architectural trim: for stone bands, sills, lintels, copings, balustrades, and door and window trimming. While it looks like natural stone, in many ways cast stone is better. It us usually stronger, resists weather better, has more color consistency, can be reinforced and costs less than natural cut stone. HOW IT'S MADE By far, the two most widely used casting methods today are the vibrant dry tamp method and the wet cast method. Natural gravel and sands that are carefully graded and washed are combined with crushed graded stone, such as granite, marble, quartz, or limestone, that meet the requirements of ASTM C 33. VIBRANT DRY TAMP METHOD In the vibrant dry tamp method, workers use a pneumatic machine to ram and vibrate moist, zero-slump concrete against rigid formwork. When the concrete is densely compacted, they remove it immediately from the form and let it cure overnight in a moist, warm room. WET CAST METHOD In the wet cast method, stone is cast in much the same way other architectural precast concrete is cast. THE FINAL STEP To ensure that cast stone undergoes minimal color and texture changes due to weathering, the outer skin of mortar is removed to expose the fine aggregates. This is done by etching the hardened stone with muriatic (hydrochloric) acid.