There has been much debate as to which doctor ring material is best for doctoring pad printing plates. The market for pad printing supplies originally started with tungsten carbide steel doctor rings and many were successfully implemented. Today, both tungsten carbide rings and zirconium oxide ceramic rings work extremely well. The zirconium oxide ceramic doctor ring offers some advantages. One of the primary advantages of the zirconia ceramic ring has a “self-lubricating” qualities that make it work equally well on thin and thick steel pad printing plate, especially the softer polymer pad printing plates.