Beneath the Plating

When A-Ling arrived at the workshop, she didn't look at the tank first; instead, she picked up the rack and held it up to the light. There was a tiny burn mark on the third contact point—the workpiece looked straight when hung, but the actual conductive area was reduced by half. "It's not the solution." She handed the rack back. "This contact point has poor contact, so the current all goes to the side. The more chemicals you add, the more chaotic the whole tank gets." A-Cheng was a bit unconvinced. This batch of workpieces was urgently needed, and changing the rack would stop the line. A-Ling didn't argue with him; she just hung two test pieces on the new and old racks respectively and put them into the tank together. Ten minutes later, the piece on the old rack was noticeably darker. They changed the rack, raised the temperature again, and added a small amount of additive according to the records. At two in the morning, the first qualified piece came out—the zinc layer was uniform, and the brightness had returned.