Ash Blue is ultramarine taken down a peg. Holbein lists PB29, described as a Complex of Silica, Alumina, Soda and Sulphur, with PBk7 carbon and PW6 titanium white. Munsell reads 3.0PB 4.5/4.0, so the value sits below mid and the chroma is low: a dusty, slate-leaning blue rather than a bright one. Worth noting that of the four Ash colours this is the one Holbein rates two stars, where the other three carry three.

This is the blue for distance, weather and shadow. It suits far hills, overcast sky, denim, worn enamel, slate roofs and the cool side of any warm subject, and because the chroma is already low it does not fight with the rest of a muted palette. Illustrators use it as the shadow blue against warm earths, and it makes convincing cool greys with nothing more than Titanium White. In flat graphic work it functions as a dark neutral that still reads as a colour, which is usually more interesting than reaching for grey.

What Makes This Colour Special

Pigment, lightfastness and series as published by Holbein. Holbein does not publish an opacity rating for individual colours; the range as a whole is described by Holbein as opaque.

Acrylic Gouache, Not Traditional Gouache

Acrylic gouache sits between two familiar paints. It handles like gouache, with high pigment and a matte finish, and it cures like acrylic, into a film that does not move. Holbein Acrylic Gouache dries to a matte opaque finish and is water resistant once dry, so it does not reactivate with water like traditional gouache. For a shadow colour like Ash Blue, being able to lay a cool pass across dried warm colour without disturbing it is the practical benefit. If you know acrylic paint, you will pick this up quickly.

Why Holbein Acrylic Gouache Is in Serious Studios

• Genuinely opaque. Holbein describes the range simply as an opaque acrylic paint. It covers, including over darker colour, which is the whole point of reaching for gouache rather than watercolour.
• Velvety matte, no sheen. Holbein describes the colour as opaque, intense, smooth and velvety. It dries flat, which is why it photographs and scans without glare.
• Water resistant once dry, so you can layer. Holbein’s own wording, and the reason the range exists. A dry layer will take another one over the top without lifting.
• The colour you mix is the colour you get. Holbein states it does not shift in colour tone from wet to dried colour. Anyone who has watched a perfect grey dry into a different grey will appreciate that.
• Built to use straight from the tube. Holbein says it is specifically designed to be used directly from the tube and will dry to even, uniform paint layers.
• Works on more than paper. Holbein lists paper, canvas, cloth, stone, wood, leather, plexiglass and concrete, with excellent adhesion, and full compatibility with all acrylic mediums.

Getting the Most Out of This Tube

Straight from the tube is the default. This is what Holbein designed it for, and it is where you get those even, flat, uniform layers. Add a little water to loosen it, but go easy: very diluted washes can dry streaky across a large flat area, so build coverage in thin even coats rather than flooding it on.

Watch the palette, not the clock. Holbein gives an open time of roughly 10 to 30 minutes and notes the drying time is much like ordinary watercolour. The practical consequence is that paint left sitting on the palette will go off and will not come back, so squeeze out small amounts as you need them.

It plays well with acrylic mediums. Holbein states the range is compatible with all acrylic mediums, so you can change the body or extend the working time if you want to. Soft synthetic brushes suit it, since they hold enough paint to lay a flat area without dragging.

Questions About Holbein Ash Blue