This research aims to study the sustainability of celadon glazes by using lampang kaolin waste and longan wood ash as substitutes for rare wood ashes, such as kha and rok fa wood, as well as for replacing silica and feldspar, which are chemicals. The celadon glazes was fired at lower temperatures of 1230°C and 1250°C in a reducing atmosphere. The analysis of the specific characteristics revealed that the glazes formula CG25-20, consisting of 30 wt.% Lampang kaolin, 20 wt.% Lampang kaolin waste, and 50 wt.% longan wood ash, with the addition of 1 wt.% sankamphaeng red clay for coloring, fired at 1250°C, had a chemical composition dominated by CaO, followed by SiO2, Fe2O3, Al2O3, K2O, TiO2, SO3, and MnO, respectively. The glaze exhibited a complete glassy morphology, with crack patterns limited to the upper surface, and the glazes adhered well to the clay body. The property tests showed that cracks decreased when 20% silica from Lampang kaolin waste was used. After firing, the glaze exhibited a green-yellow tone with L = 67.41, a = -2.13, b = +14.96, and a gloss level of 40 GU. The glazes demonstrated heat resistance, with a MOR loss percentage of 0.48, based on thermal shock testing, and had a low thermal expansion coefficient in relation to the clay body. Therefore, it is feasible to use lampang kaolin waste and longan wood ash to enhance the sustainability and heat resistance of environmentally friendly celadon glazes for ceramic ware from the sankamphaeng kiln site in Chiang Mai province.
