| National School Bus Glossy Yellow (AMS-STD 13432) | |
|---|---|
 Color coordinates | |
| Hex triplet | #f5a500 |
| sRGBB (r, g, b) | (245, 165, 0) |
| HSV (h, s, v) | (40°, 100%, 96%) |
| CIELChuv (L, C, h) | (74, 99, 48°) |
| Source | AMS Standard Color Chart, National Highway Traffic Safety Administration |
| ISCC–NBS descriptor | Vivid yellow |
| B: Normalized to [0–255] (byte) | |
School bus yellow is a color that was specifically formulated for use on school buses in North America in 1939. Originally officially named National School Bus Chrome, the color is now officially known in Canada and the U.S. as National School Bus Glossy Yellow.
The original pigment for this color was monoclinic lead(II) chromate ("chrome yellow")[1] which had superior steel-protecting properties compared to other pigments. Due to lead chromate's toxicity, a result of both its lead and chromate content, and because of lead sulfide darkening after exposure to air, the pigment was initially replaced by a mixture of cadmium sulfide ("cadmium yellow") and enough cadmium orange or selenium pigments to produce the equivalent color. However, cadmium is also an expensive and toxic heavy metal, so now many saturated-color pigments are now azo-based organics.
- ^ Worobec, Mary Devine; Hogue, Cheryl (1992). Toxic Substances Controls Guide: Federal Regulation of Chemicals in the Environment. BNA Books. p. 13. ISBN 978-0-87179-752-0.