Do not be misled by the name. Holbein publishes a value of 3.5 for Sky Blue, which is dark, alongside a chroma of 9.5 and a hue of 10.0B, so this is a deep green-leaning blue rather than the pale wash the name suggests. It is single-pigment PB15, listed as Copper Phthalocyanine, and being one pigment it mixes cleanly and tints a very long way with white, which is presumably where the name comes from.

At full strength it is closer to deep ocean or a dusk sky than a midday one, and it is excellent for exactly that: night water, storm light, the shadow inside a blue object. Its real value, though, is as a tinting blue. One tube of it plus white will give you every sky you are likely to need, from a pale horizon up to a strong overhead blue, and because there is a single pigment behind it the tints stay clean instead of turning grey. An economical choice for anyone doing a lot of blue.

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

It helps to know where this sits. Acrylic gouache is a water-based paint made for flat, matte, dense colour rather than for glazing. 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. If you already use acrylic paint the handling will feel familiar, since it is the same binder family and the same clean-up, but the surface it leaves is flat where a standard acrylic leaves a slight sheen.

Not jelly gouache, the semi-moist cup format that has become popular for lettering and small work. Those are re-wettable and made to be lifted with a damp brush. This is a tube colour with an acrylic binder that sets permanently once dry, so the two are worked in quite different ways.

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 Sky Blue