1. using CG quartz sand 2. bubble-free inner layer with coating 3. high thermal performance 4. ... %)2. coated inner layer with strict defect control(foreign inclusions, bubbles, bubble clusters, scratches/scuffs, structure faults, spikes, vapor clouds…)3. high ... IOTA-CG grade quartz sand imported from UNIMIN(USA), our Bubble-free inner layer crucibles are available for the most demanding ...