Trivalent black is a chromate conversion coating that develops a dark, even black over the zinc layer. It uses trivalent chromium, so it meets RoHS. Black chromate is chosen for appearance as often as for protection, and it is common on hardware and brackets that show in the final assembly.
A topcoat or sealer is often added when a part needs both a uniform black and higher corrosion numbers. Tell us your requirement and we will plate to it.
When to choose trivalent black
- The part is visible and needs a black finish.
- You want corrosion protection with a dark, low-glare surface.
- Your print specifies black zinc.
Black depth and evenness depend on the part and the process. Appearance-critical pieces run on the rack, where each one is handled on its own. Smaller volumes of hardware can run in the barrel.
How we plate it
We match the line to the part and watch the work at the tank. Finished parts are inspected by hand and wrapped in kraft paper so the black surface arrives the way it left. Typical turnaround is about seven days, and we expedite when you need parts sooner.
Specs and corrosion targets
We plate trivalent black to ASTM B633, military prints, and your own drawing. Send the zinc thickness and any salt spray requirement, and we set the process to meet it. We plate under your ISO and quality system.