Normal service has been suspended due to bad light, Christmas festivities, a bit of illness, and sheer laziness.
But I thought this link from Golden Paints/Williamsburg would be of interest to painters in both oil and watercolour.
Note that this doesn't apply to "Alizarin Crimson" in acrylic, because acrylics don't (and can't) use the real PR83 pigment.
https://justpaint.org/alizarin-crimson-now-you-see-it/