Smalt Blue is ultramarine with a little titanium white in it. Holbein lists PB29, the Complex of Silica, Alumina, Soda and Sulphur, alongside PW6 Titanium Dioxide, so this is a tint rather than a straight ultramarine. Munsell reads 6.0PB 5.0/12.5: a mid value of 5.0, a strong chroma of 12.5, and a hue sitting in the purple-blue band. The result is a bright, slightly softened cornflower blue. Holbein gives it three stars for lightfastness.

This is the blue illustrators reach for when pure ultramarine reads too severe. The white in it takes the edge off without dropping the chroma much, so flat areas of sky, denim, ceramic glaze and mid-distance water all sit down convincingly. It blocks in well at full strength and holds a clean edge for hard-edged graphic work. Because it already contains white it lightens smoothly with Titanium White instead of jumping in one step, and a touch of Rose Violet swings it across into clean violets. Designers keep it as a dependable mid blue that photographs and scans without shifting on them.

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 is finely ground pigment suspended in an acrylic emulsion, built to handle like gouache and cure like acrylic. 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 mid blue such as Smalt Blue that means large flat passages with no sheen bouncing light back at the viewer, plus the freedom to overpaint a shape you have changed your mind about. The full colour list sits on the Holbein Acrylic Gouache page.

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 Smalt Blue