I had 25 grill-potential covers that I examined using the technique explained by John Becker in his 8/1/20 post. I found one, light grill, on a 3¢ A46 Washington that I had previously coded as Scott #147. It is actually either #136 (most likely) or #136A. I don't intend to remove it, so is there a way on cover to better define a light grill like this? Someone indicated on the back that it is a 136 light grill.
You may be giving more credit than deserved. The point being the *camera* takes a photo square-on to the stamp with the *light* at an angle to provide shadowing from the grilling. Your first photo reverses this process.