制作彩色玻璃时需要先熔化这种特制的玻璃料。

The special ___frit needs to be melted first when making stained glass.

工人们先将石英砂和纯碱混合，然后在高温下熔制成玻璃原料。

Workers first mix quartz sand and soda ash, then ___frit them at high temperatures to make glass materials.