Overspray and rebound can be minimized by an experienced nozzleman and maintained equipment. 

Overspray is the material carried away from the surface and is common in both dry mix and wet mix methods. Overspray will adhere to forms, shooting strips, bonding wire, and reinforcing steel, leaving low-quality material. It should be removed before it hardens and to avoid the creation of sand pockets or hollows.

Rebound is mainly sand/ aggregate and cement material which ricochets off hard surfaces, such as rebars and forms and the ground/ earth (or other material) surrounding the pool. The amount of rebound varies with the position and area gunned, air pressure, water content, cement content, size and gradation of sand and the thickness of the layer being gunned. Rebound or overspray should never be salvaged or re-used in the structural part of the pool shell. 

Rebound and overspray are different from the left-over material that is being cut when forming benches and steps, the beam, and other parts of the pool when it is necessary to overbuild then cut back. 

 -taken from the 2013, third edition, V.3.3 of the builders manual of the Association of Pool and Spa Professionals

Rebound and cut material will be used and placed at the builders' discretion and all said material placement and usage will not be covered by our warranty. We highly recommend not re-using rebound material but instead, have us remove it from the pool to the outside of the pool and it be hauled off by whomever the pool contractor chooses.

Texan Gunite is not responsible nor liable for the budget and calculation of rebound (for the said project), location/ placement outside of the pool, or removal/ haul off of the rebound. This falls solely on the pool builder and cannot be back charged as unused material. This material is bought and paid for, loaded, delivered, sprayed/ shot, and shoveled out, this material is not "free" because it was refused by the process.    

For dry mix shotcrete, it is an acceptable practice that between 5%-25% of rebound be produced, with 5%-15% in the floor and slabs and 15%-25% on slopes and or vertical walls. When and if shooting overhead surfaces, 25%-50% is expected to be produced.

For wet mix shotcrete, it is an acceptable practice that up to 5% of rebound be produced for both floor/slabs and on slopes and or vertical walls. When and if shooting overhead surfaces, 10%-20% is expected to be produced. 

-taken from the 2013, third edition, V.3.3 of the builders manual of the Association of Pool and Spa Professionals