Re: Reefer Yellow/Orange

Anthony Thompson <thompson@...>

Randy Hees wrote:
Yellow and Orange have the advantage of being stable relatively inexpensive paint colors, based on Chrome Yellow and Chrome Yellow D.O. (Deep Orange) which are based on a chromium of lead (hence "chrome") and play well with the while lead paint base.
"Chromium of lead?" Randy knows his paint in most cases, but this is gibberish. The form of chromium used in pigments is normally an oxide or oxygen compound; the yellow is lead chromate, which has the formula PbCrO4. But authenitic chrome yellow has an unfortunate tendency to darken in sunlight. Many yellow paints over the last century are NOT chromium-containing.

Anthony Thompson
Dept. of Materials Science & Engineering
University of California, Berkeley

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