Mould GB-3A Black glass panel

The GB-3A article is used in the widely referenced, high-precision ASTM method D 2805 and related opacity test methods. The overall dimensions are 200 x 200 mm (8 x 8 inches). After measuring the reflectance R0 of the dry film, a certain area is scraped off the glass and weighed to determine the spreading rate or original wet film thickness. R∞ of the coloured film is determined by a separate test application. The hiding power is then calculated using the corresponding Kubelka-Munk equations in the ASTM method.

Black glass plates are used in U.S. Federal Test Method 141-4122 and CGSB Method 1-GP-71-14.7 to measure hiding power. The latter method also provides for direct measurement of wet film thickness with a pound or inter-chemical wet film thickness gauge as described in ASTM Method D 1212.

These methods depend on the unique hardness and smoothness properties of glass substrates. Although it is not as optically opaque as real Carrara glass, Leneta Black Glass has a Y-reflectance of less than 1 %, making it a suitable substitute for Carrara glass.

Specifications

• Material: Black glass
• Size:8 x 8 inch / 200 x 200 mm
• Thickness: 0.25 inch / 6 mm
• Box contents: 1
• Weight per box: 2 lb
• International standards: ASTM D2805