Glass Packaging Institute the glass finish number. For example, an 8-425 finish is approximately 8 mm neck outside diameter with a 425 finish corresponding to a threaded neck typically found on small vials. Glass Packaging Institute The Glass Packaging Institute (GPI) is the North American trade association for the glass container industry, headquartered in Arlington, Virginia. Through GPI, glass container manufacturers advocate job preservation and industry standards, and promote sound energy, environmental, and recycling policies. The GPI membership consists of 5 glass container manufacturing member companies, and 33 supplier member companies, who provide raw materials, recycled glass, equipment, decorating, and other services to
Glass (glass container coatings, glass container internal treatment), strength (toughened glass, bulletproof glass, windshields), or optical properties (insulated glazing, anti-reflective coating). Color in glass may be obtained by addition of electrically charged ions (or color centers) that are homogeneously distributed, and by precipitation of finely dispersed particles (such as in photochromic glasses). Ordinary soda-lime glass appears colorless to the naked eye when it is thin, although iron(II) oxide (FeO) impurities of up to 0.1 wt% produce a green tint, which can be viewed in thick pieces or with the aid of scientific instruments. Further FeO and chromium(III) oxide (CrO) additions may