heavydoom wrote:sometimes when we use a pu knife to hack away at the cake, and the cake is really compressed, we see yellowish dust but this is more from the metal of the knife grating the tea and so thereby forming some pu dust that looks yellow but really is in fact chalky residue of pu. what do you think? i have seen this on a few occasions.
After reading shogun's first post and seeing the pics, this is exactly what I was thinking. I bet it's just crushed leaf in the exact spot he inserted the knife. An easy way to find out...insert the knife into a different area, noting exactly where the knife touched the cake, pry apart and study the cake to see if the "yellow powder" is where the knife touched the cake. Next, take apart another area of the cake with your fingers and see if there's any "yellow powder" inside. I'll bet you'll find it's just from the knife.
When I pry apart pu, the area that the knife touched always looks different than surrounding areas. The leaves in that area are either shinier than surrounding leaves, or there's broken leaf of various sizes (including powdered leaf), ect.