GB/T 14235.3 - 1993 Focus on the determination of ash content of investment casting molds. It clearly determines the applicable range of molds, specifies the required instruments and equipment, and details the whole process from sample collection, pretreatment to ash determination, including key steps such as sample weighing, heating combustion, chill down weighing, etc. It also standardizes the calculation and reporting of results. The ash content of molds affects the mass of investment casting. This standard provides a unified detection method for the investment casting industry. It helps enterprises control the mass of molds, ensure the quality of castings, and promote the standardization of testing work in the investment casting industry.