Safe Limit of Fluoride Content for direct Silica Determination

Abstract

Opal glass, glaze and enamel compositions containing up to 7 per cent' fluorine were analysed for silica content after separating fluorine as well as by the direct gravimetric method for a comparative study. Statistical analysis of the data shows that separation of fluorine did not make any difference in the results of silica estimation. Volatilisation of silica as its fluorine compounds did not occur in these samples possibly due to the presence of alumina. It is concluded that in samples containing less than 7 per cent fluorine and 5 per cent or more of alumina, silica can be estimated without separating fluorine.