Ezi zixhobo zokuvavanya umlilo zibonelela ngokukhukuliseka kunye nokuchasana nokuqhekeka phantsi kweemeko zokusebenza ezinzima (ukuya kwi-1300ºC). I-Universal Fire Assay Crucibles zinika ubomi obude, ukudibanisa ngokukhawuleza, isantya sokunyibilika esingaguqukiyo kunye nokuxhathisa ukothuka kwe-thermal.Izinto zokwakha zikumgangatho ophezulu wodongwe oluvutha umlilo kunye nomgangatho ophezulu we-alumina obenza ukuba baxhathise uhlaselo lwe-litharge.