Ubwoya bwa Slag ni fibre imeze nka fibre fibre ikozwe mu myanda yo mu nganda (blage itanura), basalt, diabase, dolomite, nibindi, bishonga ku bushyuhe bwo hejuru bwa 1450 ° C hanyuma bikazunguruka byihuta cyane. Byakozwe nuburebure bwagenwe, kuvanaho slag, kuvura hejuru nibindi bikorwa