Laurey 54666-100 Danica Oil Rubbed Bronze Cabinet Knob - 100 Piece Set for Kitchen, Bathroom & Furniture Hardware Upgrade

These are lovely knobs. The shipment came as one large box of 4 smaller boxes of 25. I've started installing them and in the first box I've come across one knob that has a blue green residue on it that can't be removed easily. I'm sure it's from the plating chemicals they use, but of the first 25 knobs, only 24 are usable. I only needed 80 knobs, so loosing a few isn't a big deal to me... (update, I've installed 85 of the 100 knobs and of the 100 knobs 4 had discoloration, and one was drilled a bit off center, so 5 were not usable without working on them one way or another)