TAPPI T 525 om-17用于测定白色、近白色和天然有色纸浆的亮度， 纸和纸板。亮度是一个常用的行业术语，表示样品相对于特定光谱和几何特征蓝光的反射系数的数值。该方法需要使用漫反射照明和0°观察几何体的仪器。该方法适用于所有天然有色纸浆，以及由其制成的纸张和纸板。这个 该测量不适用于含有添加色素（如黄色或绿色染料）的纸张或纸板，这些色素可明显吸收光谱中约400至500 nm范围内的光。 这种亮度方法不适用于彩色纸张。待测纸浆应制成根据TAPPI T 218“成型”标准制备的手抄纸 纸浆反射率测试用手抄纸（布氏漏斗法）或T 272纸浆反射率测试用成型手抄纸（薄板加工法）。“该方法也可用于测量机器干燥板材的亮度。注1:手抄板材的亮度通常比由相同纸浆制成的机器干燥板材的亮度高0.5到1.0个单位。1.4该方法利用积分球提供漫射照明和垂直（0°） 观测几何（1）在光学术语中被指定为d/0。在这种几何形状下，试样表面结构和方位角对亮度的影响可以忽略不计。该仪器有一个相对较大的样品孔径，用于平均反射系数的小面积变化，使得只需几次单独测量就可以获得可靠的平均值。此方法不适用于有色材料。

TAPPI T 525 om-17 is for the determination of the brightness of white, near-white, and naturally colored pulp, paper, and paperboard. Brightness is a commonly used industry term for the numerical value of the reflectance factor of a sample with respect to blue light of specific spectral and geometric characteristics. This method requires an instrument employing diffuse illumination and 0° viewing geometry.This method is applicable to all naturally-colored pulps, and papers and board made therefrom. The measurement is not suitable for paper or paperboard containing added coloring matter (such as yellow or green dyestuff) which appreciably absorbs light in that part of the spectrum extending from about 400 to 500 nm. This brightness method is not applicable to colored papers.Pulps to be tested shall be made into handsheets prepared according to TAPPI T 218 "Forming Handsheets for Reflectance Tests of Pulp (Buchner Funnel Procedure)" or T 272 "Forming Handsheets for Reflectance Tests of Pulp (Sheet Machine Procedure)." This method can also be used to measure the brightness of machine-dried sheets.NOTE 1: The brightness of a handsheet will usually be 0.5 to 1.0 units higher than that of a machine-dried sheet made from the same pulp.1.4 This method utilizes an integrating sphere to provide diffuse illumination and perpendicular (0°) observation geometry (1) designated in optical terminology as d/0. With this geometry, specimen surface structure and azimuthal orientation have a negligible effect on brightness.The instrument has a relatively large specimen aperture for the purpose of averaging small area variations in reflectance, making it possible to obtain a reliable average value with only a few individual measurements.This method is not intended for use with colored materials.