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| Linda Working on a Color Chart |
Thanks again to all who attended our Jan. 30 meeting!
A question came up about paints with the same pigment number that are different colors. Linda Koffenberger, (who teaches art at NCBG and has a professional background in paint color mixing), answered our question here:
"The first example is Ultramarine Blue, which comes either with a red bias or a green bias. Both are coded as PB29. The reddish-toned Ultramarine is usually sold as French Ultramarine and the cooler, greenish-toned one is sold just as Ultramarine Blue. Originally Ultramarine was a mined pigment made from Lapis Lazuli and was the most expensive pigment there was. Then in the 1800's, a way to manufacture it was invented. The process uses silica (or sand) and "Ultramarine poor in silica" has the greenish-tone and the "Ultramarine rich in silica" as the red tinge.
The second example is Yellow Oxide, a naturally occurring mineral. Its chemical name is iron(III) oxide-hydroxide. It is sold under the name Yellow Oxide, however, and the code on the tube is PY42. The thing is this mineral can be any where from yellow to dark-brown and even black. So the pigment manufacture tries to blend batches to make the color uniform from one tube to the next. But another manufacture may have a slight different blend so the color varies from manufacture to manufacture."
A question came up about paints with the same pigment number that are different colors. Linda Koffenberger, (who teaches art at NCBG and has a professional background in paint color mixing), answered our question here:
"The first example is Ultramarine Blue, which comes either with a red bias or a green bias. Both are coded as PB29. The reddish-toned Ultramarine is usually sold as French Ultramarine and the cooler, greenish-toned one is sold just as Ultramarine Blue. Originally Ultramarine was a mined pigment made from Lapis Lazuli and was the most expensive pigment there was. Then in the 1800's, a way to manufacture it was invented. The process uses silica (or sand) and "Ultramarine poor in silica" has the greenish-tone and the "Ultramarine rich in silica" as the red tinge.
The second example is Yellow Oxide, a naturally occurring mineral. Its chemical name is iron(III) oxide-hydroxide. It is sold under the name Yellow Oxide, however, and the code on the tube is PY42. The thing is this mineral can be any where from yellow to dark-brown and even black. So the pigment manufacture tries to blend batches to make the color uniform from one tube to the next. But another manufacture may have a slight different blend so the color varies from manufacture to manufacture."
