According to Progressive Surface, a manufacturer of water-jet cleaning systems, waterjet cleaning uses extremely high water pressure to strip coatings and contaminants off the object being cleaned. A nozzle is selected based on the type of surface/debris to remove. The process involves pumping the water stream through the nozzle onto the object. Some kind of barrier is needed to contain the water and retain the removed coating and debris.
Progressive Surface explains the process of erosion is used to remove hard surfaces such as metal or carbide thermal spray coatings, and the process of delamination is used to remove soft surfaces such as paint, adhesives and grease.
For hard surfaces, a nozzle is selected that breaks the water up into individual droplets so they can erode the surface off the object without affecting the material of the object being cleaned. For soft surfaces, a nozzle is selected that keeps the water focused into one stream so it can move into the interface between the surface and the object and peel the surface off by the process of delamination. Delamination can remove surface materials and debris much faster than erosion-based techniques without harming the underlying substrate at all. Erosion-based waterjet cleaning techniques are similar in principle to sand-blasting cleaning methods but remove less of the underlying substrate.