Today, instead of pumping his own concrete, the busy contractor sometimes calls in a specialist- one of a small breed of men with a particularly intense knowledge of one subject: pumping concrete. Pumping services relieve the contractor of a sizeable investment in equipment, maintenance problems and a full-time operator who may not be fully utilized. The service operator may also be in a better position to maintain his equipment and keep it up to date. In return for his fee, the pumping service operator provides the equipment and an operator, who from the very nature of his work often has far more experience in pumping concrete on the job then his contractor counterpart. Charges are generally based on a per cubic yard rate although a few use rates computed on an hourly basis. One pumping service even offers a technique for pumping concrete form the bottom up. The feat is accomplished by using a special valve of their own design. The valve is placed in the lower portion of the form, a hose nozzle is attached to the valve and the pump is started. As the concrete rises in the form the air is automatically forced out. This eliminates the necessity for vibrating. When the pumping is completed it is self-closing and seals against leakage. When the forms are stripped the surface is said to be so smooth that very little if any finishing is required. Usually the only additional forming needed would be a short length of 2 inch by 3 inch or 2 inch by 4 inch set vertically on center, on both the front and back sides of an average column, plus forming material of not less than five-eighths of an inch plywood.