A COMPARISON OF ULTRAVIOLET-LIGHT AND BENZIDINE STAIN FOR DETERMININGHEARTWOOD SAPWOOD BOUNDARIES IN RED PINE

Thirteen cross-sectional samples of red pine (Pinus resinosa Ait.) wer e used to examine differences in estimation of heartwood area using ul traviolet light and benzidine stain. The samples were sanded and exami ned under ultraviolet light. Heartwood boundaries were marked on each sample, and the sample was then photocopied. Samples were sanded again to remove existing markings, stained, and photocopied. The heartwood areas were then carefully removed from the photocopies using a razor b lade. A Delta-T area meter was used to determine heartwood area (cm2) per sample. Comparison of ultraviolet and staining data by a paired t- test indicated no significant difference between means at the 0.10 lev el. The use of ultraviolet light in red pine appears not only to be an acceptable method of measurement, but also is efficient and nontoxic in comparison to staining techniques.