Tempered clear or clear glass is advantageous for boiler engines & the like. For thicknesses ranging from 5 mm - 19 mm.
hardened glass by heating ordinary float glass to temperatures around 500 ° C and then cooled suddenly by spraying air evenly on the two glass surfaces. From this procession there is a physical change in the glass which is a change in the compressive and tensile forces of the glass, but visually