View Full Version : I don't understand phthalo blue as a primary

03-09-2001, 07:06 AM
I'd like to use only three primaries (plus white) to mix all other colors, and without using warm and cool variations of each.

I usually hear the following recommended as primaries:

-hansa yellow (arylide yellow)light or medium
-quinacridone magenta
-phthalo blue(either ordinary or green shade)

How can phthalo blue be the best blue to use as a primary when it's slightly greenish? When mixing it with magenta to make purple, won't the slight green in it mix with the red/magenta (compliments)to make a dull, greyish or brownish purple?

But color printers use yellow (perhaps arylide?), magenta (quinacridone?) and cyan (phthalo?), so cyan, even though it may look slightly greenish, maybe it really is the true primary, and maybe most blues are actually a bit reddish, and thus are not true primaries? This is the only way I can think of to explain why phthalo blue/cyan is so often used as a primary, despite looking slightly greenish.

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03-09-2001, 10:12 PM
are you talking watercolour, acrylic or oil?


03-10-2001, 12:51 AM
Hi Dommer, your question is also THE big question that I have right now...Unfortunately, I am only a beginner with color and don't have much experience to share...I'm hoping that the triad of colors you mentioned will work..because they seem to be the modern organic dyes and are less expensive than the mineral based colors. I had a talk with an excellent artist this past weekend who only uses three primaries and two earth colors, his colors are really fine, brilliant and portray an amazing range of subtle changes...his name is Mark Brown and is a young painter in Phila. who does amazingly realistic still lifes...His three primaries are Cad yellow, W+N bright red and Colbolt blue...also, Burnt Umber, Burnt Sienna and Permalba white...he said that it took him a few years before he could get to where he could do it all with this pallette. I was told by a teacher that the organic dye colors (arylides, Napthols, Dioxy..) do NOT mix well in that, if you do a lot of manipulation of the paint, it loses it's bright color....there is a book by Kevin D. Macpherson "Fill you Oil Painting with Light and Color" wherein he uses only a limited pallette of; Cad yellow pale, Alarizon Crimson, Ultramarine blue and Windsor green...he shows how to easily mix the earth colors..in my opinion, his pictures have a nice unifying look to them in that the colors are so closely related...(my opinion only)..they are not my style though, and I don't know if it is because of his pallette or just that my taste is somewhat different..anyway, this is a great topic and I hope that many different views are expressed on this thread.....many thanks

Painting the light reflecting upon an object is different from painting the object

03-10-2001, 05:07 AM
I'm talking all mediums here. I use water-miscible oils and acrylics, but I can't see why this wouldn't apply to watercolors too. And computer color printers and printing presses, etc. Any subtractive color mixing.

To Mario, that artist you mentioned, like many others, uses yellow, bright red and cobalt blue if I remember. My understanding (I could be wrong here) is that, unlike what art teachers always say, red is not a true primary because reds usually contain some orange/yellow, and that
red can actually be made by mixing quinacridone magenta with a small amount of primary yellow (look at your computer printer...it prints red just fine... by mixing magenta plus yellow)...proof that red is not a primary!
I believe that cobalt blue is very slightly purplish (meaning it contians a bit of red...or perhaps more accurately, magenta) and therefore is also not a true primary. Mix
it with yellow and you get a dull green. You need a true primary blue/cyan, which is appearently phthalo blue. Which I still don't fully understand because it's slightly greenish.

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[This message has been edited by Domer (edited March 10, 2001).]

[This message has been edited by Domer (edited March 10, 2001).]

03-10-2001, 08:24 AM
They work! Have you tried them? You really have to be careful with the phthalo colors, esp. blue, it will just take over if you let it. On a trip to Mexico a few years ago I took white, thalo blue, permanent rose, and a transparent yellow, can't remember which one. That was it. Nothing else was needed.



03-10-2001, 10:36 PM
thalo is not a true blue. cobalt is a closer color to the primary blue.

"it's alright to be judgmental,,,,,,,,if you have taste"...MILT

03-11-2001, 11:22 PM
Actually...I think of the color wheel as a theory to be manipulated and used. I don't believe any pigmented color really defines THEE true red, blue, or yellow.

If you think of each primary of the wheel having two natures, a cool nature...and a warm one, then you'll expand the power of your ability to command contrast effects, and cover anything nature throws at you.

thus...I use a thalo blue for my warm, a French ultramarie for my cool. A Red Cadmium med for my warm...a Rose Madder or Alizarin Crimson for my cool...and, a Cadmium Yellow Med for my warm yellow, and a Hansa for my cool.

Why limit yourself to the burden of finding THEE blue? Think warm and cool colors, and it will all fall into place and make a lot more sense, and arm you much better.


The Artsmentor

"Painting is easy when you don't know how, but very difficult when you do!" Edgar Degas

03-14-2001, 09:01 PM
Larry I., Totally agree with your excellent response!

John H
03-14-2001, 11:40 PM

The last image on this page might help:

In printing, blue is actually a secondary (cyan plus magenta make blue). CMY's mixing range is a lot smaller than what we can achieve with a fuller pallet.