Trivalent yellow is a chromate conversion coating applied over fresh zinc plating. It runs on trivalent chromium chemistry, so it carries no hexavalent chromium and meets RoHS and ELV requirements. The color is a warm gold with the shifting iridescence that gives the finish its name.
Under that color sits the zinc, which is the layer that actually protects the steel. The yellow chromate seals the zinc and adds corrosion life on top of it.
When to choose trivalent yellow
Yellow chromate gives more corrosion protection than a clear passivate, which is why it shows up on so much steel hardware. Reach for it when:
- Your print calls for a yellow or gold zinc finish.
- You are replacing a hexavalent yellow finish to meet RoHS.
- The part is a fastener, stamping, bracket, or formed steel piece headed for indoor or sheltered service.
- You want solid corrosion protection at a working price.
How we plate it
Both of our lines run trivalent yellow. We match the method to the part. High counts of small parts go through the barrel for even coverage. Parts that cannot tumble, or that need a cleaner cosmetic result, run on the rack and are handled one at a time.
A plater watches the bath and the parts as the work moves, so problems get caught at the tank. Finished parts are inspected by hand and wrapped in kraft paper for the trip back. Typical turnaround is about seven days, and we expedite when a line is waiting.
Specs and corrosion targets
We plate trivalent yellow to ASTM B633, to military prints, and to your own drawing. Tell us the zinc thickness and the salt spray hours to white or red rust you need to hit, and we set the process to meet it. Most of our customers run their own ISO and quality systems, and we plate to those requirements so the parts drop straight into your process.