1) Ukuminyana okuphezulu, ukumelana okuhle kwamakhemikhali
2) Ukumelana okuhle kwezinga lokushisa: Ukusetshenziswa isikhathi eside ngo-1600°C, isikhathi esifushane ngo-1800°C
I-3), ukumelana kahle nokupholisa okusheshayo nokushisa okusheshayo, akulula ukuqhuma.
4) Ukukhishwa kwe-slip kanye nokuminyana okuphezulu
5) Izinhlobo ezahlukene zokuma nobukhulu.