These black streaks occur when the cake pan is spun during the manufacturing process. It is a natural occurrence in the material. We are proud to use 100% pure organic aluminum without any additives. This discolouration can be removed with vinegar or lemon juice, the discolouration does not impact the performance of the pans.
Before I use my pans, I found some black dirt in the bottom of the pan. I washed so many times and still it hasn’t disappeared?Admin