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Old 11-19-2017, 06:26 PM
Clotmonet Clotmonet is offline
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My color theory broke

I've been reading about chromatic blacks so much lately that I thought I'd try it. Well, actually I have been adding white so I can see the hue, I guess I'm really chasing a medium gray.

Step 1 Prussian blue + burnt sienna, obviously brown
Step 2 carefully added Prussian Blue, but the brown moved smoothly to olive green then started getting distinctly bluish.
Step 3 add Burnt Sienna to return to the middle point, a somewhat greyed out olive green
Well if it's green it needs red to neutralize right?
Step 4 added Primary Red. This helped, but the best thing I found in a series of mixes was quite greyed-out olive green... but the green was pretty obviously still there. More red gave a definite reddish tint to my mud.

Neutral gray was very surprisingly elusive. I conclude that
my chromatic black was off the mark, since it could not make a very good neutral grey.

Should I abandon the theory approach and just look up standard cookbook mixes for chromatic black? If I use cookbook recipes, will the resulting black be sufficiently neutral that I can add white to get flat grey? Just how precise do I need to be anyhow?
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Old 11-19-2017, 07:20 PM
ntl ntl is offline
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Re: My color theory broke

When I used Prussian blue and burnt sienna, my red was alizarin crimson. I don't have the painting any more, but I remember it--as a background color--as rich and very black. I did not try to turn it gray.
Are your paints single pigments?
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Old 11-19-2017, 09:00 PM
Clotmonet Clotmonet is offline
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Re: My color theory broke

The white and burnt sienna are from Rembrandt. The Prussian blue is a cheap brand, Georgian or some such, but I believe it to be genuine because the pigment is not expensive and it makes green just like the real thing. Brilliant greens, very pure. The primary red is suspect, but.... there are also inexpensive versions of crimson so a cheapo brand would not have to resort to mixes.

I think I found the problem though. I was assuming I could hit grey by picking a complement and adding it. Fine theory, but what if your estimate of a complement is off? What if the complement doesn't come in a tube?

After quite a long think, I started pushing the mix very cold with prussian blue, then pushed it back to quite warm with my best fake criimson. rinse and repeat. This process steadily converged on neutral gray but used quite a bit of paint.

It would appear the complement to the olive green I was searching for was off in the violet/purple part of the color wheel. The whole mess could probably have been avoided by going direct to deep purple with prussian blue and crimson, and then carefully adding sienna in small quantities.

Long story short, if you pull a tube of paint out of your box, it is very unlikely that there is another tube in the box that complements it. This must be why people memorize chromatic black recipes - it just so happens there IS a complementary pair of red and green that works right out of the tubes, or very close to it. But I'm betting you'd have to pick the exact brand and color to make it work.

Well it was a very educational evening. Can't complain.

btw your method rings a loud bell. Rembrandt is making a pretty nifty Alizarin alternative that Jason Walcott recommended. I'm itchin to try a chromatic black with it.

So, when you do the alizarin mix, what sequence do you follow? Are the quantities roughly equal?
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Old 11-19-2017, 09:49 PM
ntl ntl is offline
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Re: My color theory broke

Oh my, that was a long time ago. I AM sure I started with tiny amounts, I'd guess the blue and the brown, and added the red, in teeny bits. MY paint was probably really old, so a possibly a different quality, so you're off on an adventure! Enjoy!
It's really fun when it's not frustrating!
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Old 11-19-2017, 10:14 PM
Clotmonet Clotmonet is offline
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Re: My color theory broke

I just had to test my ideas one more time, and this time I nailed it with much less mixing and without excess paint use.

I ended up using about 4 parts prussian blue, 3 parts ordinary crimson (not alizarin) to get a deep dark purple and then put in about a half part of burnt sienna maybe less. Pulling out a small sample of the resulting black and mixing it with white gave a dead neutral gray.

I can't explain why the sienna wanted to dominate so. The red and blue I was using were Wal Mart grade, and the sienna was proper artist paint from Rembrandt. Can the pigment loadings be that drastically different?

I have to agree its really fun when it's not frustrating and tonight I had nothing but time on my hands. Thanks for playing along.
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Old 11-19-2017, 11:00 PM
ntl ntl is offline
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Re: My color theory broke

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Old 11-20-2017, 09:10 AM
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Re: My color theory broke

Quote:
Originally Posted by ntl
The goal is "do not use Black because it kills every color". Even if Prussian blue + Sienna mix crappy color, that mixture worse a waste of time. You will get color, which nobody can describe as a Black. Therefore, if it is not a real black, it can't "kill colors". If it can't kill colors, then it is "most useful mixture in the world" as this mess can't affect other paint.
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Old 11-20-2017, 09:34 AM
Clotmonet Clotmonet is offline
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Re: My color theory broke

I agree , there are strange differences between chromatic black and, say, ivory black. Just scrape the thinnest possible layer across a white pallette and it's a world of difference. I'm guessing it's because some of the pigments used in the chromatic black are stainers and others aren't, and since the staining properties are out of balance you get color in the stain.

I just noticed that Alizarin is transparent, Burnt Sienna is transparent and Prussian blue is somewhat transparent. Does anyone use Transparent Oxide Red instead of Burnt Sienna? Can all this transparency be exploited for visual effects? What would a term like "Transparent Black" even mean?

It's a strange world down there where the chromatic blacks live.
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Old 11-20-2017, 09:51 AM
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Re: My color theory broke

Quote:
Originally Posted by Clotmonet
Does anyone use Transparent Oxide Red instead of Burnt Sienna? Can all this transparency be exploited for visual effects? What would a term like "Transparent Black" even mean?
Transparent oxide is synthetic version of burnt sienna. Usually it is more vivid color but not as dark as sienna in masstone. When applied thinly, it gives highly saturated orange color.
Quinacridone Red PR209 mixed with Phthalo Emerald PG36 will make good "chromatic" Black. But my favorite "chromatic" darks is a touch of Lamp Black mixed into transparent COLOR. Chromatic blue black can be mixed with Ultramarine, Chromatic red Black can be mixed with fake Alizarin Crimsons, Chromatic green Black mixed with Chromium Oxide green and Chromatic brown Black mixed with tr.Oxides. Add Lamp Black to ANY paint to mix your own "chromatic" black mess.

Last edited by Gigalot : 11-20-2017 at 09:54 AM.
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Old 11-20-2017, 10:48 AM
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Pinguino Pinguino is offline
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Re: My color theory broke

I find that these make very good chromatic black, or at least a very neutral dark gray:

(1) W&N Transparent Red Ochre + Rembrandt Phthalo Blue (Green Shade). The PB-GS (PB15:4 or PB15:3) can probably be used from any brand. But the W&N-TRO is definitely not the same as "transparent red oxide" in other brands. The Transparent Red Ochre is distinctively reddish, whereas comparable transparent red oxides are more like burnt sienna. If the mix is a slight mis-match, then the resulting hue is probably desirable.

(2) Gamblin Raw Umber + Ultramarine Blue. The UB can probably be any brand. It is my understanding that the properties of Raw Umber tend to vary from brand to brand. If the mix is a slight mis-match, then the result is probably desirable.

(3) Gamblin Phthalo Green (Yellow Shade) PG36 + Quinacridone Red/Violet, PV19. Gamblin sells this pre-mixed as a Chromatic Black. I could not obtain a very neutral blend by using either Quin Red or Quin Violet alone, but could get it with a blend of both. Don't know if that's what Gamblin does. In any case, this particular blend is harder to manage than the others, since a slight mis-match will likely produce a hue that you don't want.

All of the above are semi-transparent, leaning toward transparent, which is desirable.
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Old 11-20-2017, 02:56 PM
ntl ntl is offline
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Re: My color theory broke

Quote:
Originally Posted by Clotmonet
... Alizarin is transparent, Burnt Sienna is transparent and Prussian blue is somewhat transparent. ...Can all this transparency be exploited for visual effects? What would a term like "Transparent Black" even mean?
It's a strange world down there where the chromatic blacks live.

I did a plein air that had sun over my back, and a shadow on crushed gravel. I made a transparent chromatic black for the shadow, and was very pleased. The black was transparent, laying on the browns, reds, grays of the gravel.
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Old 11-20-2017, 10:32 PM
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Re: My color theory broke

What would "transparent black" even mean?

Visualize a pattern of alternating black and white vertical stripes. Then, paint a horizontal stripe of the color to be tested.

If the color is perfectly opaque, then you will not be able to see darker and lighter patches in the horizontal stripe, even though there are darker and lighter areas beneath it. All of the horizontal stripe will be the characteristic color of the test paint.

If the color is perfectly transparent, you will distinctly see darker and lighter patches. The darks areas will be very dark, and the light areas will be the characteristic color of the test paint.

A semi-transparent paint is somewhere in-between. The dark areas will be lightened, generally revealing where the test paint was slightly thicker, in the brush strokes. The light areas will still be the characteristic color of the paint.

So, "transparent black" does indeed make sense. It darkens light areas, without much affecting areas that are already dark. So, an underlying pattern shows through.

However, "transparent white" does not make sense. That would lighten dark areas, but in a way that obscured the underlying pattern. That's why Zinc White, often called a "transparent white," is said to create a foggy effect when applied over other paint.

The concept of a "chromatic black" is that (unlike Ivory or Mars blacks) it is very non-flat across the spectrum. By itself, it appears black, because our eyes perceive it as flat. But when mixed with other colors (or applied as glaze) the non-uniform color absorption will interact with the other paint, shifting some colors one way, some another way.
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Old 11-21-2017, 01:23 AM
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Re: My color theory broke

Chromatic black is nothing, but a concept of "do not use black". Black paint is always more useful that any mess, it is lightfast, deep, cheap and mono-pigmented. If you need a color into Black, then add what you like into Black paint or add Black paint into color paint. There is nothing to be "advantage" in messy blacks. Even if you need extremely deep black, diox mixed with Lamp gives that darkness.
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Old 11-21-2017, 10:03 AM
redgreen redgreen is offline
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Re: My color theory broke

I guess that using Lamp Versus Ivory would make these transparent colours opaque. This would be useful for direct thicker painting.
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Old 11-21-2017, 04:53 PM
Clotmonet Clotmonet is offline
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Re: My color theory broke

Quote:
Originally Posted by ntl
I did a plein air that had sun over my back, and a shadow on crushed gravel. I made a transparent chromatic black for the shadow, and was very pleased. The black was transparent, laying on the browns, reds, grays of the gravel.

Omg I never thought of that. Very clever.
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