Phthalo pigments are a family of blue and green synthetic organic pigments based on variants of copper phthalocyanine, a deep blue compound produced by the reaction of phthalic anhydride, urea, copper and ammonia. It was first sold as a pigment in 1935 under the trade name Monastral Blue (some paint manufacturers still use this name). When it was discovered, it was thought to be the most significant advance in artist pigments since the discovery of synthetic Ultramarine Blue in 1826.
Phthalo pigments are transparent, highly staining, and reliably lightfast. They are commonly used in industrial and printing applications, as well as in artist paints. Phthalocyanine dye is even used as a toothpaste colourant.
The spectrum of Phthalo pigments ranges from deep, warm blues to cool spring greens. There are red and green shades of Phthalo Blue available in many artist paint ranges, as well as two different Phthalo green pigments. In this article, I explore the differences between them, and the unique qualities they bring to an artist palette.
From left to right:
Michael Harding Oil Paint, Phthalo Green Yellow Shade
Jackson’s Artist Watercolour, Phthalocyanine Blue
Jackson’s Artist Watercolour, Phthalocyanine Green Deep
Daniel Smith Watercolour, Phthalo Blue Green Shade
Daniel Smith Watercolour, Phthalo Blue Red Shade.
Phthalo Blue, Green Shade (PB15, PB15:3)
With its distinctive green undertones and cool temperature, Phthalo Blue Green Shade is considered the ‘default’ Phthalo Blue. Some paint ranges have only one Phthalo Blue, and if a red or a green shade is not specified the paint is most likely to be a green shade of Phthalo Blue. When using a split primary palette, a green shade of Phthalo Blue is a good choice for a cool blue.
Left: Phthalo Blue Green Shade in tints with Titanium White.
Right: Phthalo Blue Green Shade in mixtures with Cadmium Red Light, Lemon Yellow, Burnt Umber, and Indian Yellow Hue
With an opaque and highly tinting red like Cadmium Red Light, it makes a strong, semi-transparent near-black. Mixed with lemon yellow (another cool pigment), it produces sharp and vibrant greens. In tints with white, Phthalo Blue Green Shade makes a sky-blue colour similar to Cerulean Blue. This could be useful for watercolourists who prefer non-granulating pigments, but who like the softness of Cerulean. It is also capable of mixing some natural greens when mixed with an earth colour or a warm yellow, as seen above with Burnt Umber and Indian Yellow.
Phthalo Blue, Red Shade (PB15, PB15:1)
Phthalo Blue Red Shade is a warmer variant of Phthalo Blue Green Shade. It is similar in masstone (its appearance neat from the tube) to Prussian Blue but has the clean brightness of Ultramarine Blue when thinned. It is a useful colour for artists who want to achieve dark, warm values in their paintings. The following is a comparison between Phthalo Blue Red Shade and Phthalo Blue Green Shade when mixed with the same colours:
Left: Phthalo Blue Red Shade with Lemon Yellow (left column), Indian Yellow Hue (centre column), and Alizarin Crimson (right column), with increasing amounts of the other colour added to Phthalo blue as you move down the chart.
Right: Phthalo Blue Green Shade with Alizarin Crimson (left column), Indian Yellow Hue (centre column), and Lemon Yellow (right column), with increasing amounts of the other colour added to Phthalo blue as you move down the chart.
The colour mixtures are quite similar, but the difference in colour temperature could make all of the difference in a palette. Natural greens are easier to reach with the redder shade of Phthalo Blue, while Phthalo Blue Green Shade created more acidic, synthetic looking greens (those these could be neutralised with the addition of a red pigment). When choosing between a green shade or a red shade of Phthalo Blue, it is recommended to consider the overall temperature of the painting. The Phthalo Blue Green Shade will contribute to a general cool mood of a painting, while the red shade can impart more warmth.
Phthalo Green (PG7)
Phthalo Green pigment absorbs more blue light than Phthalo Blue, and this is achieved by chlorinating copper phthalocyanine pigment. It is a velvety colour with very deep, blue undertones.
Left: Phthalo Green Shade in tints with Titanium White.
Right: Phthalo Blue Green Shade in mixtures with Burnt Sienna, Lemon Yellow, Indian Yellow Hue, and Alizarin Crimson
Its depth of colour, as well as its luminous transparency, means that Phthalo Green lends itself well to seascapes. When mixed with white, it makes a range of turquoises. While many landscape artists choose to mix their own greens rather than using it from the tube, Phthalo Green can still make a useful addition to a landscape palette. By adjusting it with Burnt Sienna or another earth colour, its blue undertones are neutralised and it produced some deep browns. Mixing Phthalo Green with Alizarin Crimson makes a chromatic shadowy black.
Phthalo Green, Yellow Shade (PG36)
Usually a little more expensive than the other Phthalo pigments, Phthalo Green Yellow Shade is made by treating copper phthalocyanine with bromine. It is a very clean, emerald green with more yellow undertones. Like Phthalo Green, it makes an interesting addition to a landscape palette when mixed with an earth colour and makes some deep blacks when mixed with red. One of its most exciting mixing compliments is lemon yellow, which makes almost fluorescent greens (seen below).
We would love to know how you use Phthalo pigments. Some artists find their extraordinarily high tinting strength unhelpful (one artist I spoke to called them ‘inconsiderate’ pigments because they overwhelm other colours), while others love that they are capable of both incredible depths of colour and delicate transparent glazes when thinned. Let us know by leaving a comment below.
Product ranges referenced in this article:
More articles about pigments and colour mixing:
- The Enduring Appeal of Alizarin Crimson
- The Story of Ultramarine Blue and French Ultramarine
- Comparing Black Pigments, and Getting the Most out of Using Black in your Palette
I adore the effect of adding
phthaloturquoise to cobalt violet, it
makes a fabulous dark with lots of
vibrancy
I’ll have to try that combination, thanks for the suggestion Gillian!
I adore Phthalo Blue PB15 in my
watercolor work, but rarely on it’s own. It’s
an amazing color to have for mixing
purples with Magenta PR122. I also love it
for making more natural olive-leaning
greens with Nickel Azo Yellow PY150. It’s
awesome that it’s so strong, as a tube can
last you forever. Learning to use just a tiny
touch of your paint when mixing can help
you overcome that feeling of it being “too
overpowering”.
Thanks for your comment! It’s true that Phthalo paints are great value – a little goes such a long way.
Great article! I use the Akua Intaglio pthalo inks for
printmaking but you’ve brought up so new mixes for me to
try…
Thank you Sally!
Whilst not an experienced painter, I really appreciate these articles as I learn so much about the technical side of paint/ing and feel I am getting some real art training here. Thank you.
That’s so wonderful to hear, thank you.
Both Phthalo, blue gs and phthalo green
are wonderful in seascapes. Additionally
phthalo blue gs mixed with burnt umber
Produces a great cool landscape Earth
tone.
Wonderful, thank you Drew
I’ve found the transparency of Phthalo
blue beautiful to flood over areas of
impasto and smooth areas of paint… it
stains them all differently.
Also transparent Phthalo blue mixed
with opaque French Vermillion
watercolour makes great ‘blacks’.
Enjoyed this thread of discussion very
much. Thanks
Wonderful, thank you for your comment! It’s so great to hear how artists use Phthalo Blue. Lots of colour mixing inspiration.
I particularly like the pthalo blues for
creating a night sky in some of my quirkier
paintings. White / silver stars and moon
shine out against it. Paynes Grey or black
create the silhouettes.
Yes, they’re lovely for night skies. Thanks for your comments Margaret!
I am fascinated with Pthalo Blue and Pthalo
Green watching Bob Ross landscapes so
really appreciate this article
/podcast/whatever
Yes! Bob Ross is so relaxing to watch as well. Thanks for your comments Yvonne.
Whilst I don’t consider myself a painter as
such, I have always painted with various
media, mixing whatever colours I have to
hand. Your series on the properties and
values of various pigments is fascinating
and I’ll definitely be more considered next
time I come to buy paint.
I’ve tended to think more in terms of
colour/shade as opposed to properties/
transparencies/ granulation etc.
Thank you!
Hi Lyn, thanks for your comments. We’re glad this article will help you with your next paint colour selections.
I really like phtalo blue. A valuable bit of
information on this color may be, as
Handprint also mentions, that Winsor &
Newton have the greatest hue difference
in their green shade and red shade.
Definitely more than Daniel Smith. I have
both phtalo blues by W&N in my palet and
because of their difference they both find
their own way in mixes.
Just my two cents!
That’s so useful to know! I’ll have to compare the two Winsor and Newton shades.
Thank you so much for this article. I totally understand
some artists avoidance of these pigments for more natural
shades, but for me the colours I gravitate towards are
those that give me the greatest mixing capabiluty. I’ve been
researching pigments for the last few years as I find the
whole subject fascinating and I have branched out into
making my own paint as I want to feel more connected to
the whole process in my art. Every time I configure a palette
without the phthalo colours in it I feel a bit lost. Even if I
know a style of painting doesn’t need it, I want to know I
can mix that bright deep turquoise if I want to. I personally
love them because they are bright and clean and I know I
can always subdue them, but I can’t make a duller pigment
brighter. For me they are a must have.
A huge thank you to Jackson’s for these interesting and
informative articles. They are a wonderful resource.
Thank you for sharing Suzi! I used to avoid Phthalo pigments (and other strong, highly tinting pigments) but I’ve recently come to love them and find them very valuable now.
I use Phthalo blue (green shade) and Phthalo
green (blue shade) frequently. Although I do
use tertiary colours, I generally prefer to mix
my tertiaries by utilising the properties of
complementary pairs, I find the resulting
mixes are more vibrant. When wanting
secondaries I generally mix, but for the
complementary pairings I like the
convenience of a handy tube. I am currently
working an acrylic head and shoulders
portrait and am using Phthalo Blue as my
dark toned blue and cerulean for the lights. I
can achieve a good range of tertiary skin
tones when mixing with cadmium orange
and/or cadmium red. The Phthalos must be
used cautiously because of their strength
but I find them invaluable to my way of
working. You can get a lovely tertiary violet
with the blue and alizarin crimson, great for
distant warm seas, mountains and skies. The
green content, being the complementary of
the red takes the ‘oomph’ out of the mix.
Hi Amanda,
Thank you for sharing your colour mixes with us.
Hi Evie, I was interested to see that you graduated from Camberwell in 2016. I graduated from there in 1979 with a first class BA Hons in Painting, and I’m still doing it! I use Golden heavybody acrylic Phthalo Blue (green shade) and Phthalo Green (blue shade) as I find they complement each other well. Yes, they are strong pigments, but you can always reduce their strength by adding the complementary or warming them up with yellow ochre or red oxide. It’s easier, in my opinion, to start with a strong colour and make it more subtle through mixing, but well nigh impossible to start with a dull colour and increase it’s intensity by adding other colours to it. Best of luck with your career btw!
So great to hear from another Camberwell alumnus! You’re right that it’s much easier to start with a strong, clean colour and take it down as needed. I used to avoid Phthalo pigments because I found them difficult to handle, but it turns out that they’ve solved many of my colour mixing problems.
Interestingly I usually use both the green
and blue shades for cooler colours, but in
the way I sometimes grade my colours
move from intense pure to richer pale
warm greens mixing with Cadmium Deep
yellow.
I can picture those rich warm greens, thank you for your comment Peter!
I use Phthalo Green Yellow shade a lot. In
fact apart from olive green, that I use
sometimes as a shortcut in my landscapes,
the green yellow shade is the only green I
have. I will mix it with ivory black when I
want a very dark real life green for dark
trees. The black adds a bit of warmth to it
and I modulate the mix to get different
greens to which, if I need lighter green, I will
add dark yellow cad and white as I need. I
couldn’t live without that Phthalo ! I use
also the blue with red shade.
That mixture of Phthalo Green Yellow Shade and Black sounds delicious. If it was a transparent black I bet that would make some beautiful washes and glazes. Thank you for your comment!
Thank you for the good info, Ms Hatch.
Always had issues with Phthalos feeling
overwhelming, but recently, thanks to your
Materials Guide interview with David
Coles, gave Phthalo Turquoise a shot. I’m
seeing rich turquoises in my pix I never
thought to pursue before. I was at least
half-hoping you’d talk about that color
here. Can you say how it’s made and make
suggestions for pairing it, please?
Thanks for your comment Lawrence, I completely neglected to mention Phthalo Turquoise. In some ranges it is a mixture of PB15 and PG7, but in others it is single pigment PB16. According to Handprint it is wonderful with red-shade orange and orange-red pigments. A previous comment suggests mixing it with Cobalt Violet. I have to admit I’ve never tried it.. I’ll try these mixtures out and add it to the post. Thank you for pointing this out!
This is a wonderful and informative article,
glad I came across this! I use Phthalo
Turquoise PB16 in my palette (based on
Handprint’s “Secondary Palette”, opposed
to the default PB15:3, and I love it. I’ve
been used to Phthalo pigments almost my
entire painting life, and although they are
staining, I’m glad these pigment types
exist.
Also I wonder how Holbein makes their
Primary Cyan. It’s formulated with PB15,
but how do they manage to get their Cyan
to be that bright? Holbein is known for not
having opacifiers in their gouache, so is it
a chemical process to make PB15
significantly lighter?
Thank you for your comment! I’m not sure how they make their Cyan so bright, but as you say they don’t use opacifying fillers so I imagine it is the way the pigment has been processed.
Great post. I just recently discovered your
blog. Not only are there well-explored
topics, and wonderful artists, but I also
enjoy the interesting comments by readers.
Thanks so much. Much appreciated.
Thank you Deborah!
I love the Phthalos and consider PG7 an essential palette colour. It’s such a great shortcut to mixing greens when plein air or landscape painting, and I don’t have to worry about it muddying other colours. Plus, phthalo’s transparency means that these pigments really flow on a page. You just can’t get the same effects from granulating or opaque pigments. I agree with the other commenters: tinting strength plus low prices make phthalos an economical choice for a palette, and although you can easily subdue a phthalo (and a quin – those can be just as aggressive!) you can’t brighten a dull pigment. For those that struggle with intensity, try using it dried in a pan vs straight from a tube. This can help immensely!
I have been a long time user of phthalo blue
and green (and turquoise recently) and I
absolutely love the intensity they bring. A
little goes a very long way so you have to
use them with restraint but I see this as an
advantage. Adding warmer colours to them
can also help to tone them down when you
need to. I think they are really versatile and a
total necessity in my palette. Thanks for this
post.
Wonderful, thank you for your thoughts Alison
I’m one of those who find them annoyingly
strong. However, there is no other non toxic
cool blue in the golden range so I’m stuck
with it.
I like to think of Phthalo Blue as a concentrate, good value for money cos you only need a smidge! But I also like it, makes great purples.
It’s not just the Golden range. There aren’t that many blue pigments in existence, we don’t have many choices.