How was varnish detected prior to this technology?

Prior to the development of QSA®, there was virtually no mechanism to provide an early warning of an impending varnish problem. Historically, the most common way of detecting varnish was by visual observation of easily viewed surfaces in the system. Unfortunately, dirty sight glasses and “bathtub rings” in lubricant reservoirs often do not show up until the contamination level has reached critical stage. All too often, unexpected varnish deposits were observed on internal components such as valves, bearings and gears during unscheduled and costly shutdowns or failures.