Black glass is used in widely referenced high-precision ASTM Method D 2805, and related hiding power test methods. After measuring the reflectance R0 of the dry film, a defined area is scraped from the glass and weighed to obtain the spreading rate or original wet film thickness. R∞ of the paint film is obtained from a separate test application. The hiding power is then calculated from the appropriate Kubelka-Munk equations found in the ASTM method. Blacklite: Refers to the Leneta type of black glass.
Black glass panels are used in U.S. Federal Test Method 141-4122 and CGSB Method 1-GP-71-14.7 for measuring hiding power. The latter method also provides for direct wet film thickness measurements using a Pfund or Inter-chemical type of wet film thickness gage, as described in ASTM Method D 1212.
These methods depend on the unique hardness and levelness characteristics of glass substrates. Leneta black glass is much superior in levelness to previously available striated types.
Although visually not as opaque as true Carrara Glass, Blacklite Glass has a transmission of less than 1%, making it an adequate substitute for Carrara Glass.