Yes, a waterjet can effectively cut reflective materials such as copper and brass, and it does so without the major difficulties that lasers face. This makes waterjet a preferred or even necessary method for many applications involving highly reflective metals.

Lasers struggle with copper and brass primarily because these materials reflect a significant portion of the laser’s wavelength, especially in the near-infrared range that most fiber and CO₂ lasers use. The reflected energy can damage the laser optics, reduce cutting efficiency, and cause inconsistent edge quality. Additionally, copper’s high thermal conductivity quickly dissipates heat, preventing the laser from establishing a stable cutting front.

A waterjet, whether pure water or abrasive, overcomes these issues entirely because its cutting mechanism is purely mechanical. There is no optical absorption, reflection, or thermal involvement. The high-pressure stream of water mixed with garnet abrasive erodes the material through impact and shearing. Reflectivity has no effect on this process—copper and brass cut just as readily as steel or aluminum, provided the material thickness is within the machine’s capability.

For thin copper or brass sheets (up to approximately 1/8 to 1/4 inch), pure waterjet is often sufficient. The high-velocity water alone can cut soft, ductile reflective metals cleanly without abrasive. For thicker plates (1/2 inch and above), abrasive waterjet is required. At 50,000–60,000 psi, abrasive waterjet can cut copper or brass up to 2 inches or more with a smooth, burr-free edge and no heat-affected zone. There is no melting, no discoloration, and no work hardening.

Another advantage is that waterjet cutting does not create a reflective or glazed cut edge. Lasers sometimes produce a highly reflective molten recast layer that can interfere with subsequent welding or coating. The waterjet leaves a natural, matte finish that is ready for secondary operations.

Practical cutting speeds for 1/4-inch copper with an abrasive waterjet at 60,000 psi are approximately 6–10 inches per minute, similar to mild steel. Because copper is softer but more ductile than steel, speeds may be adjusted slightly, but no special precautions are needed.

In summary, waterjet cutting handles copper, brass, and other reflective materials without difficulty. It eliminates the risk of back-reflection damage, produces no thermal distortion, and maintains consistent edge quality across varying thicknesses. For shops that regularly process reflective non-ferrous metals, a waterjet is often a more reliable and versatile solution than a laser.