Exclusively using Pyrex and Symax laboratory glassware that is made out of borosilicate glass. Glass-blown, using glassblowing technique that requires aerating molten glass into a bubble with the aid of a blowpipe. Expert artisans combining the centuries old traditional glass blowing techniques. Heat Treatment and Tempering. Our cruets are four times stronger and safer then untreated glass. Tempered glass is less likely to experience a thermal break, therefore our cruets are bacteria- and heat crack free. Strictly washed with distilled water resulting in a clear non-drip glass.