Intensive quenching (IQ) has been defined as “those quenching conditions that lead to uniform maximum surface compressive stresses,” which provide maximum surface compressive stresses with correspondingly optimized distortion control. An earlier paper described the design and construction of a laboratory system that provides sufficient heat transfer rates to be classified as an IQ system. This paper describes the experimental work conducted with this laboratory IQ system. Particular focus will be on construction and use of this laboratory device to quench SAE 5160 spring steel under IQ conditions and the corresponding cooling curves, heat transfer rates, and compressive stresses obtained.