Many studies have been conducted to replace lead based materials with non-lead materials in the Plasma Display Panel (PDP) industry, because of the environmental problems posed by the former. One of the problems encountered in wet milling is the elution of the alkaline components of the frits, which are added to improve the thermal properties of the components of PDP. The purpose of our study is to investigate quantitatively the improvement of the frit surface afforded by thermal treatment. After making frits with an average particle size of 2-3 mu m through wet milling, they were heat treated at different temperatures below the glass transition temperature of the glass. Using DTA, XRD, FT-IR and FE-SEM, we studied the improvement of the frit surface by examining the weight loss, images of the frit surface, the crystalline phases and the hydroxyl content.