Gamblin FastMatte Alkyd Artist Grade Oils - Phthalo Blue
Phthalo Blue is an essential for every oil paintbox. Because there is no perfectly primary mixing blue, this is one of the two blues you will need for a primary palette. Ultramarine Blue is almost primary, but has a trace of red in it. You will also need to buy Phthalo Blue, which is almost primary, but with a trace of yellow. Since almost all things in nature have a trace of red, your ultramarine is your go-to blue primary, fitting the bill for almost all destination colours. For colours without any red, like high-key turquoises, Phthalo Blue is your ticket. If you are trying to get a primary blue, mix Ultramarine and Phthalo Blues together, and the traces of red and yellow will be virtually undetectable.
Both colours are transparent, and mix well with white to create opaque blues. They, of course are excellent glazing colours.
FastMattes are wonderful, strong, lightfast, highly pigmented alkyd paints, specifically formulated by Gamblin to work exceptionally well in foundation applications. They also work remarkably well in all applications, with their fabulous pigmentation, quick drying quality and stiff consistency which can be customized to any level of creaminess with addition of medium. If used "out of the tube" they are incredibly good for palette knife applications, because they hold their marks so well and are evenly matte. Get 'um while you can. They have been discontinued except Titanium White (thank goodness they still make that!)