Cov iav iav feem ntau siv thaum lub sijhawm sim, yog li kev sib tsoo muaj ntau, yog li nws tseem ceeb heev kom paub cov khoom ntawm iav ua ntej siv glassware.Hardness ———– hardness yog 6 ~ 7, nkig, tawg yog lub plhaub zoo li cov cuab yeej ntse. .Strength ———– Muaj zog tiv taus siab tab sis tsis muaj zog tensile lub zog, yooj yim rau tawg.Heat resistance ——– tsis zoo thermal conductivity,