This study investigates the reasons why certain glass products, such as super clear glass and tempered glass, have become in demand after a period of decline in consumption. The main points' 1. Super clear float glass, although developed in Japan, did not become widespread, because of high cost. 2. Demand for super clear float glass increased, because of a trend of transparent architecture and ceramic printed glass in Europe. 3. There was a decline in demand of tempered glass, because of spontaneous breakage and internal restriction of glass manufacturers. 4. Demand for tempered glass increased, because of safety guideline regarding designing glass windows and an emerging trend of transparent architecture and structural usage of glass.