Hi All,

I dyed a test board with TransTint dye, then brushed a coat of shellac over it (canned stuff, 2 lb de-waxed). Now, when I spin my test board 360 deg while looking at it obliquely, I see two maximum and two minimum intensities of reflection. This directionality of reflection cannot go unnoticed. It reminds me of looking at certain minerals under a cross polarized microscope (back in my geology days). Before brushing shellac over the surface, light reflection was completely diffuse and I did not see any directionality of light reflection (or any specular reflection for that matter). This has me wondering if shellac has an oriented crystalline structure to it that reflects light differently in different directions. Definitely makes it tricky to measure the color of dyed wood. I guess that’s the lac bug for you. Has anyone else noticed this directionality of reflection from a shellacked surface? 

Just found this post which sounds related to what I’m talking about:
https://www.researchgate.net/figure/Polarized-light-microscopy-images-depicting-the-effect-of-the-cooling-rates-on-the_fig2_235770460

Old_wood_guy