High Chroma Turquoise Here We Come! These Blazing Blues are Some of the World's Most Powerful Paints
And did you ever notice that Old Holland has three different kinds of phthalo blue all labeled with the same pigment? (Edit: This recently changed!)
Let's dive into this and more.
Lightfast, high chroma, transparent
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 (though there were some interesting wildcards in the lightfastness department when Williamsburg performed lightfastness testing in different white paints. See their research on lightfastness for more details). For context, when we say Phthalo Blue Green Shade, we're talking about a very blue-blue. The "green shade" (or sometimes "red shade") part indicates a small but important difference in the way the color is pitched in hue that allows this variety of phthalo (in this case,the Green Shade) to create mixes for some of the brightest blue-greens. Phthalo Blue in its various forms is known by the code PB15, and after this code you might (or might not) find variations specified 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. In masstone these colors will tend to look pretty dark, but when thinned they reveal high chroma.
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.
The number following the pigment code may mean a slightly different hue
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. PB15 is the main pigment code for Phthalo Blue, however sometimes a brand will add a number that indicates the variety of phthalo. This is very helpful, and we wish all brands would do this. Usually PB15:3 and PB15:4 are the greenest (more cyan blue or cerulean), and paints labeled PB15:1 or even PB15:2 tend to be redder, meaning a more royal blue, a step closer to ultramarine.
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 can make a difference.
With a pigment like phthalo, the hue differences between brands of the same phthalo variant may not be as enormous as say, cadmiums or cobalts. Even in the ultramarines we saw more variety between student and premium brands than we did in phthalos. However differences in the pigment code are helpful when sorting out whether a color is what they call a red shade or a 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 which is difficult to accurately represent. The featured paints discussed in the article are on the panel to the left.
It has a particular character that is too powerful for some. Also a note of caution on older tubes.
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, so some painters prefer genuine ceruleans, PB35, which is a little less chromatic and mixes differently with other colors. It all depends on your painting practice.
So, as with many modern or inexpensive pigments like phthalo blue or even phthalo green, the differences between brands do not seem to be as pronounced. 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.
The first question is do you need phthalo, and the second is, do you need it in a premium brand. This is an area where some people even prefer student brands sometimes (we don't tend to subscribe to this) because having higher tinting strength in a pigment like this is sometimes too much for a painter. For us, we are used to it, and it seems like the better question to ask would be what consistency does a person prefer and which binding oil is needed.
All of these high-end brands performed fantastically and all felt like 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.
We often mention we cannot comment on all of the health hazards found in pigments/paints, since we are not toxicologists (we are are 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, and possibly even new ones) 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 at one time to inquire about their pigment 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, and also check your modern ones to be sure the pigment that the manufacturer uses is free of PCBs. Currently the only way we know of to do this is to contact the manufacturer.
Slight Variations in hue can be see among the Various Phthalo Blue Oil Paints- Note the slight difference in the tints
New Pigment Information to be Published on Tubes
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. When this article was first published, Old Holland, who had no less than three phthalo blues all labeled PB15 without much more clarification. These were, Old Holland Blue Lake, Scheveningen Blue Deep, and Old Holland Blue. To make it even a bit more mysterious they also had one labeled PB15:3, Scheveningen Blue.
For reference, we noticed on the Winsor and Newton site that their Winsor Blue Green Shade is also listed as PB15 (no qualifier). We would assume this is PB15:3 given the Green Shade name, however that is not certain unless the pigment variety is stated.
In order to sort the Old Holland varieties, we bought all three and tested them.
Since this article was first published, we had been corresponding with Artist Ian Goldsmith, founder of the CBPP, who raised awareness about the need for better labeling for pigments, especially in the Phthalos. Aquil Copier, Artist and Technical Advisor at Old Holland, responded and updated the pigment info for tubes of Old Holland paint. We are glad to report that the world now has a clearer concept of the varieties of phthalo that are in these colors, which will serve artists going into the future.
Updated pigment information for Old Holland (July 2024) is, Old Holland Blue Lake, PB15:1, Scheveningen Blue Deep, PB15:2, Old Holland Blue, PB15:6, and Scheveningen Blue, PB15:3.
A big thanks to both Ian and Aquil for making this happen.
Old Holland has a lot of variety in its single-pigment phthalos. Phthalo blue in its various forms is a popular component of convenience blends as well. However each form of phthalo as a single-pigment has slightly different properties. This can actually be seen here-- as the last column (to the right) is a different form than the rest of the paints on the panel.
The featured oil paints which have a variety of shades and tinting strengths. We noticed that brands with alternative binding oils tended to have slightly higher chroma. The last two columns on the right are Old Holland Colors, PB15:3 and PB15:1
Old Holland offers tremendous diversity in this range, and will be implementing greater detail for phthalo blues in their pigment labeling. (Not all of them are featured in the photos from this review, so you can explore them here)
Higher Chroma but 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 appearing to re-liquify again after it was thought to be dried (it turns out this is a complex phenomenon which is not totally understood). If you are using a safflower oil paint it is important to understand how to use it and whether it is worth it to you to use it in your work.
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. Painter lore has it that Winsor and Newton's Winsor Blue Green Shade is one of the better choices for mixing the highest chroma teals. They list this color as being a blend of linseed and safflower oil. 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, especially safflower and poppy.
A Group of Phthalo Blues
Of the six colors featured in this review, these are most likely bound in linseed oil
Of the six featured colors in this review, these have another known oil besides linseed. Some may be blends, some may be purely another oil. Blockx is Poppyseed oil while W&N list theirs as a Linseed/Safflower Oil blend
There are not enormous differences in hue across the colors, with the exception of the Old Holland Blue Lake, which it turned out was PB15:1 (a slightly different kind of phthalo). The Old Holland Scheveningen Blue, PB15:3 was a bit of a gentler tinter, though differences in tinting strength take on different meanings with phthalos. The tint it created was lovely and had an ever so slightly different character than some of the others. Some of the biggest differences in this group of paints come in their binding oils.
These colors are mostly PB15:3. They varied only a little in hue but they differend in handling
Discover more PB15:3 paints on Paint List
