There isn't a universally mandated minimum thickness for black fiberglass tissue. However, the thickness can vary based on the specific application and industry standards. Typically, fiberglass tissues are available in various thicknesses ranging from very thin (e.g., 0.013 inches) to thicker options. The choice of thickness depends on the strength, durability, and insulation requirements of the project. It's essential to consult the manufacturer's specifications or industry guidelines for the appropriate thickness for your specific use case.