How do you make the brightest blues in oil paint?

Does it matter which brand of phthalo blue you buy?

Are there any differences between premium brands?

And did you ever notice that Old Holland has three different kinds of phthalo blue all labeled with the same pigment?

Let's dive into this and more.

In this post we'll be exploring the paints in the top panel: a collection of Phthalo Blues by Blockx, Michael Harding, Winsor and Newton, Williamsburg, and Old Holland.

Phthalo Blue- that powerhouse blue that makes the glint on the wing of a Lazuli Bunting or the cerulean sparkle in that Caribbean Wave

Phthalo Blue Green Shade is the closest thing to a cyan in modern oil colors. Sometimes called by its fuller name Phthalocyanine Blue, this color often comes out of the tube very dark and creates brilliantly chromatic blue glazes when thinned or mixed with white. This stunning and generally lightfast blue is naturally transparent. For context, when we say Phthalo Blue Green Shade, we're talking about a very blue-blue. The "shade" part indicates a small but important difference in the way the color is pitched in hue that allows this variety of phthalo to create mixes for some of the brightest blue-greens. Phthalo Blue is known by the code PB15, and after this code you might (or might not) find variations like PB15:1, usually a blue closer to royal blue which is called "Red Shade," by PB15:3 which is used in teals and ceruleans called "Green Shade," or PB15:4, which is sometimes used in Manganese Blue substitutes, just to name a few.

Phthalo Blue Green Shade refers to PB15:3. Sometimes paint manufacturers add the "3" after the PB15, and sometimes they seem to leave it off. We always appreciate when they specify because if you need this color to mix the brightest blue greens, the PB15:3 variety does make a difference.

With a pigment like phthalo, the differences between brands may not be as enormous as say, cadmiums or cobalts. Even in the ultramarines we saw more variety between student and premium brands. However if you like a brand for its handling or want to have special properties like the more non-yellowing attributes of a certain oil binder, it’s interesting to see what the premium brands have to offer and how they differ amongst themselves.

Different Kinds of Phthalo Blue and Their Labels

Phthalo Blues vary in undertone as well as in consistency. As far as the hue of Phthalo Blues, these often follow patterns among the pigment labels. Usually PB15:3 and PB15:4 are the greenest (more cyan blue or cerulean), and paints labeled PB15:1 tend to be redder, meaning a more royal blue, a step closer to ultramarine.

Phthalo Powerhouse- Too Powerful for Some

Do you need this color in your paintbox? For some (like us) it's an absolute essential. However there are some painters who opt for other blues because this color can quickly overpower a mix. A little goes a long way. There is also a very distinctive high chroma to this color that can end up being a little pronounced in a mix. It all depends on your painting practice.

So, as with many modern or inexpensive pigments, the differences between brands are not usually huge. So we wondered whether premium brands made a difference. These high power phthalos surprised us a bit in that they actually had differences-- those differences ended up being mostly differences in handling.

A Quick Note on Older Tubes of Phthalo

We often mention we cannot comment on all of the health hazards found in pigments/paints, since we are not toxicologists (we are a bunch of artists). However it was so surprising to us that we wanted to mention to others that older tubes of phthalo (pre 1982 or so, though really just all old phthalos) can contain toxins called PCBs. These can also exist in modern phthalos depending on where the pigment was manufactured. We actually sent letters out to manufacturers once to inquire about their sources since PCBs are toxic. Do your research, look it up, check it out. So this is a heads up on avoiding those old tubes of phthalo paint-- this applies to all phthalos not just Phthalo Blue Green Shade.

In the photo above, we added a few more phthalos in addition to the ones we're featuring here. Some of the variety in tinting strength shows up in this image. This image was keyed a bit bluer-- these paints are a blue green. The featured paints are on the panel to the left.

Which Phthalo is Which? --Old Holland has Three, oh wait, Four

With some brands, their labeling made it confusing to understand which of the several phthalo varieties we were buying, so we also wanted to sort that out. One example of this is, Old Holland, who has no less than three phthalo blues— all labeled PB15: Old Holland Blue Lake, Scheveningen Blue Deep, Old Holland Blue. To make it even a bit more mysterious they also have one labeled PB15:3, Scheveningen Blue.

In order to sort this out we bought all three and tested them.

Premium Brands

All of these brands performed fantastically and all were sound paints with good tinting strength. The super high chroma of this oil paint comes out when thinned into a glaze or when mixed with white. Here we mixed out the phthalos with Williamsburg Titanium White to see the differences. The semi-circles show the paints mixed 1:1 with white to show the tinting strength. To thin out the paints, we used a bit of Rublev Oleogel to create a glaze at the top.

Mind the Binding Oils- Higher Chroma with Tradeoffs

Whether a paint is bound in linseed oil can make a bit of a noticeable difference to the hue in this range. In general a small saturation boost can be achieved with safflower oil, however one is then painting with safflower oil and needs to be mindful of the drawbacks as well as the benefits. There have apparently been issues with safflower oil liquifying again after it was thought to be dried.

Along with a slight chroma boost with safflower oil, we noticed that Blockx Primary Blue in poppyseed oil had a chroma advantage. Similarly, we noticed a slight chroma boost in a color which is bound in walnut oil (not shown here), namely M Graham’s Phthalocyanine Blue PB15:3 had an advantage in chromatic tints as well. The theme here is that for the brightest blues there may be a slight gain in chroma in non-linseed binding oils, however there are always the tradeoffs associated with those oils.

Paints made with alternative binding oils sometimes had higher chroma.