Basis Weight
The basis weight of paper is the weight in grams of its 1m².
Brightness
Brightness is the capability of paper of reflecting the light that reaches onto it.
Color
Papers are classified in terms of color and hues according to the rate of reflecting all L*a*b* [L* = (0) zero: black, (100) one hundred: white, a* = (+) positive: red, (-) negative: green, b* = (+) positive: yellow, (-) negative: blue] colors that form the light. The paper which reflect L*a*b* values equally is white paper. However, the papers which do not reflect equally are perceived by the human eye in the color that emerges as a result of the rates of the colors they reflect.
Opacity
The opacity of paper is in direct proportion to the rate of reflecting the light that reaches onto it. In case of a paper with high opacity, the inscription, image, etc. printed on one side is not seen on the other side.