Sometimes my students ask me why I don't recommend certain colors and here is one of those I find very useful but still don't talk very much about. A company in Germany manufactured real Manganese Blue pigment until new environmental regulations were passed 25 years ago. Because the industrial use was limited to tinting concrete, this pigment is heading for the exit, Lukas being the only paint maker that still keeps any amounts of it. The other manufacturers produce "hues" that are completely different. So what do I do? Well, Prussian is the only blue I actually need and my paintings do benefit from a limited palette, so I keep this beauty out of my harem but reserve a spot for it up my sleeve as long as it lasts.