Indanthrone is a warm blue with a nice range from very deep blackish blue to a washed denim tone. I have recently added this colour to my stash. The colour was discovered in 1901 as a vat dye. The etymology for Indanthrone probably originates from the scientific vocabulary, German indanthrene + English one *
Here you can see my use of Indanthrone PB60 from Daniel Smith in this giant wave, in a landscape as snow shadows and as mixed.