Lezi zinhlayiya zokuhlola umlilo zihlinzeka ngokuguguleka nokumelana nokuqhekeka ngaphansi kwezimo zokusebenza ezinzima (kufika ku-1300ºC). I-Universal Fire Assay Crucibles inikeza impilo ende, ukuhlanganisa okusheshayo, isivinini sokuncibilika esingashintshi kanye nokumelana nokushaqeka kwe-thermal.Izinto zokwakha wubumba oluvutha umlilo lwekhwalithi ephezulu olunokuqukethwe kwe-alumina ephezulu okubenza bamelane nokuhlasela kwe-litharge.