Phthalo Blue (red shade) PB15:0

Very strong, dark, and high chroma blue. Transparent in masstone, but quickly becomes opaque when mixed with a little white. When lightened to a mid value it gives a very neutral blue.  Its 'red shade' name is based on a direct comparison with the 'green shade' phthalocyanine blue.  It sits in the colour space between Phthalo blue green shade (cool blue) and Ultramarine blue (warm blue).