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PIGMENTS: Ultramarine Blue vs. Phthalo Blue


When I first started painting as a college student I was quickly overwhelmed by how many pigments there were to choose from. While as a child I would often reach for "blue", I was simultaneously tickled and dismayed to learn that I was suddenly on the hook to decide between ultramarine blue, phthalo blue, cerulean blue, and a litany of other variations that I had never even heard of before.


Making things more confusing was the fact that many paint brands had different names for similar pigments. "What's the difference between 'ultramarine' and 'French ultramarine'?" my friends and I would ask each other. "And also, why is one tube of paint twice as expensive?"

Funnily enough I did not start really clearing these things up until I left my college studio art class and: 1) decided to write my senior Art History thesis on the chemical industry and it's impact on innovations in artist's paint (Sooooo exciting, I know!!!) and 2) took a summer class at a Pennsylvania atelier, Barnstone Studios, where we did a number of heinously painful color wheel studies. In fact, those color studies and my senior thesis were both excruciating in their own way- further proof that to progress, we must often experience pain! :D


Understanding the true nature of pigments is a lifelong learning experience that all artists who use color have embarked upon, willingly or not. One awesome takeaway from my senior thesis was the interview I did with the late Carl Plansky, professional paint slinger and founder of Williamsburg Handmade Oil Colors. He told me this crazy, wonderful story about searching the world for rare pigments both to sell through his company and to use in his own painting. On one particular occasion he became obsessed with finding the violet that Monet used in his Water Lilies series. Apparently this particular pigment was in limited supply (I can't remember the reason why and I've lost my copy of my thesis so... 0-0) but he was able to get his hands on a small volume of it. Carl saved it for years until finally using it in one of his own paintings.


Image of Claude Monet's painting "water lilies"
One of Monet's "Water Lily" painting. Is that gorgeous hue our mystery violet? WikiCommons

Carl Plansky was obsessed with pigments for much the same reason that artists throughout the ages and even kings and queens have been: each pigment is a unique, precious and unlikely substance. You might look at a blob of paint on a canvas and say "Oh, that's blue" when in fact you are looking at a particular pigment that was chosen specifically for its opacity or transparency, its violet or green persuasion, how it behaves when mixed with the whites or blacks that artist had at their disposal and, of course, how much it cost. You might be looking at crushed up rock harvested from a mountainside in Afghanistan or the product of metallurgical technologies in Ancient Egypt. Crazy, right?!


I've come to feel that one of the principal pleasures and privileges as an watercolor artist is how much time we must spend with these pigments, studying their habits and proclivities. Two pigments that I worked extensively with this weekend while creating my Librarian Witches series and a Blossom Baby portrait are Ultramarine Blue and Phthalo Blue.

Color swatch of Ultramarine Blue watercolor paint
Ultramarine Blue plays well with others
Color swatch of Phthalo Blue watercolor pigment
Phthalo Blue shows off its mad staining power

Here's a quick rundown of the differences between Ultramarine Blue & Phthalo Blue, as I've observed them. Remember that this reflects qualities of watercolor pigments, the medium I've been working in lately:


Ultramarine Blue

-violet tinge relative to other blues

-sometimes chalky in texture

-medium staining power. If you put it down in the wrong place you can often pick it back up if you move quickly enough.

-lovely dark value when applied thickly out of the tube

-very common so it's easy to acquire and easy to match in other mediums

-medium intensity as compared with other blues

-mixes well with most other colors, a palette essential

-I USE THIS WATERCOLOR PIGMENT WHEN: I need a gentle blue that goes well with everything else and blends into lovely browns and grays.

Spoof on Michelangelo's "Creation of Adam" with Adam wearing boxer shorts.
I drew this funny "Creation of Adam" sketch with ultramarine colored pencil

Phthalo Blue

-green tinge relative to other blues

-usually very smooth in texture

-high staining. Once you put phthalo down you usually can't pick it back up again

-quite dark value when thickly applied out of the tube

-very intense. If you are trying to develop a vivid, almost electric looking palette this blue is a go to

-a little trickier to mix than ultramarine blue, in part because it is so intense and overwhelms more subtle colors. Test your mixes before applying!

-I USE THIS WATERCOLOR PIGMENT WHEN: I want a blue that is vibrant, catches the eye, and serves as an anchor point for a vivid, clear color palette.



Sketch of two children riding in barrels in the ocean
...and this sketch of intrepid kiddos in phthalo colored pencil

That's it for now on my favorite blue watercolor pigments and pigment musings generally! I hope this article helps you on your art education journey. Happy painting.



Click HERE to see paintings in my sketchbook, including paintings like this page of beach observations created with phthalo blue ink and QOR watercolor paint.


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