Reflectances and colors are given for various natural woods. The results are summarized in a table, which gives the coefficients for empirical equations that fit all the spectral reflectance curves, and a second table which gives integrated values obtained by the analytic method. Clear varnish is found to reduce reflectance to approximately 85 percent of that for the unvarnished wood.
PARRY MOON and DOMINA EBERLE SPENCER, "The Color of Unstained Wood," J. Opt. Soc. Am. 38, 405-408 (1948)