The wooden dark box is in accordance with the national standard GB/T1721-2008 "Determination of Appearance and Transparency of Varnish, Varnish and Thinner", GB/T1722 "Determination of Color of Varnish, Varnish and Thinner", GB/T1726-1989 "Paint Hiding Power Assay" design. It can also be used for color matching of paint films under specific light sources.
The inner wall of the dark box is painted with black matte paint. Two 15-watt fluorescent tubes placed in parallel are installed on the upper part of the dark box. Open for testing.
The transparency, color and hiding power of varnishes need to be evaluated under a specific light source.
And it is required that there is no reflection or interference of other light sources around, and the inner wall of the dark box is coated with a matte black body to avoid light source interference.

GB/T 1721, 1722, 1726