Color Spotlight: Phthalo Blue Red Shade (PB15:6)

Daniel Smith – Phthalo Blue Red Shade (PB15:1)

Is Phthalo Blue Red Shade actually red-toned, neutral, or still green-toned but simply less so than its cousin Phthalo Blue Green Shade (PB15:3)? I’ve heard all opinions, and I suppose it’s a judgment call. (Is the color blue you see the same as the color blue I see?) My opinion is that it is a fairly neutral blue without a clear bias toward purple or green. But it’s just as strong and lively as its Phthalo kin.

Experiment Results

Gradient: Deep, dark navy to pale sky blue, through medium blue. (The photo makes it look more cyan than it is in real life. It’s more neutral blue.)

Opacity: Totally transparent.

Glazing: Glazes super dark, almost black.

Lifting Tests: Wet Paint/Dry Paper Towel vs Dry Paint/Wet Paper Towel

Lifting: I was initially scared off of using this as a sky color because of the Phthalos’ reputation as being “not liftable,” but in testing, I found it to be totally liftable – maybe not as cleanly as Cerulean, but it’s a marginal difference. The wet-paint lift left behind a bit of blue, and the dry-paint lift required a bit of elbow grease, but these are definitely recognizable clouds.

Comparison to Other Colors

Honestly very similar to Phthalo Blue Green Shade (PB15:3), but less green-toned. Here’s a comparison of the Holbein versions, with the “Red Shade” on the left.

Holbein’s Phthalo Blue Red Shade vs. Phthalo Blue Yellow Shade (aka Green Shade)

They can both get very dark. In masstone I think they look like pretty similar navy blues. I see the difference more in the mid to light tones, where PBGS tends toward aqua but PBRS is more powder blue.

Here’s a quick rundown of the differences as far as I can tell:

SituationGreen/Yellow ShadeRed Shade
Painting the SkyNot quite realistic sky color (too green), except possibly for very close to the horizon.Good overall blue mid-sky color.
Mixing GreensMixes maximally vibrant, borderline neon greens, like grass green and spring green. With yellow, similar color to Phthalo Green YS. Mixes slightly more subtle greens like hunter and jade. With yellow, similar color to Prussian Green or Cascade Green.
Mixing PurplesMixes slightly more subtle purples like eggplant and periwinkle.Mixes maximally vibrant purples like royal purple and lilac.
Neutralizing (Mixing Gray)Complement is orange-toned red such as Pyrrol Scarlet or Scarlet Lake.Complement is red-toned orange such as Transparent Pyrrol Orange.

Comparison to Other Brands

Most brands offers a Phthalo Blue Red Shade equivalent, although some of them use PB15:1 and some use PB15:6. I’m not sure if there’s really a difference in color – if there is, I can’t see it.

Da Vinci – Phthalo Blue Red Shade (PB15)

Da Vinci – Phthalo Blue Red Shade

Looks about the same to me. Perhaps slightly less overwhelmingly strong than DS, which is good actually (easier to mix).

Holbein – Phthalo Blue Red Shade (PB15:1)

Holbein – Phthalo Blue Red Shade

Very similar to DV.

Lightfastness Test for Holbein PBRS

Lightfastness test for Holbein Phthalo Blue RS (PB15). Left: window swatch, exposed to western light in Boston, MA, from May 30-December 9, 2023. Right: Protected strip.

I really see no difference between these. Great Job!

Winsor & Newton – Winsor Blue (Red Shade)

WN – Winsor Blue (Red Shade)

Very similar hue in midtone, a bit more difficult to get very dark, and I got a lot of blooms in the accidentally overdiluted paint in the bottom. This one I found slightly tricky.

Color Mixes

Rich Green Gold (PY129)

HO Phthalo Blue Red Shade (PB15) + DS Rich Green Gold (PY129) on Canson XL

Lovely natural-yet-bold turquoise-green to sap green hues.

Nickel Azo Yellow (PY150)

HO Phthalo Blue Red Shade + MI Green Gold (PY150)

Bright, sunny, very well-mixed greens. NAY is just a perfect mixing yellow.

Imidazolone Yellow (PY154)

Phthalo Blue Red Shade (PB15) + Mission Gold Permanent Yellow Light (PY154) on Canson XL

Mixes with a basic middle primary yellow are similar to, but somehow not as magical as, the mixes with Nickel Azo Yellow (in my opinion).

Quinacridone Gold (PY150 + PO48)

HO Phthalo Blue Red Shade + DS Quin Gold on Canson XL

More muted sap greens.

Isoindolinone Yellow Deep (PY110)

HO Phthalo Blue Red Shade (PB15) + HO Isoindolinone Yellow Deep (PY110)

Muted yellow-greens very similar to those with Quin Gold.

Transparent Pyrrol Orange (PO71)

Transparent Pyrrol Orange + Phthalo Blue Red Shade
DS Transparent Pyrrol Orange (PO71) + DS Phthalo Blue Red Shade (PB15:6) on Canson XL paper

I think a fairly neutral gray is possible here, though I didn’t quite find it. Orange-browns on the TPO side, and neutralized warm blue-blacks on the PBRS side. This is an interesting combo!

I also tried Winsor & Newton’s Transparent Orange, which is not necessarily PO71 (it’s called “DPP”) but is quite similar.

WN Transparent Orange (DPP) on HO Phthalo Blue Red Shade (PB15) on Canson XL

Benzimida Orange Deep (PO36)

DV Benzimida Orange Deep (PO36) + HO Phthalo Blue Red Shade (PB15) on Canson XL

Very similar to the Transparent Oranges, but maybe a little worse? Nice muted teals when it’s mostly PBRS, but otherwise quite ugly browns.

Pyrrol Orange (PO73)

Da Vinci Orange (PO73) + HO Phthalo Blue Red Shade (PB15) on Canson XL

Weirdly violet-ish blues, but kind of ugly IMO. It’s funny because PO73 looks more like an orange than a red unmixed, but it makes more violety mixes than does Pyrrol Scarlet (PR255), which looks more like a red.

Pyrrol Scarlet (PR255)

HO Phthalo Blue Red Shade (PB15) + DS Pyrrol Scarlet (PR255) on Canson XL

Violet-grays and muted browns that I don’t really like. PR255 is definitely good at muting the blue though I think it muted PBGS better than PBRS.

Naphthol Red (PR188)

DV Permanent Red (PR188) + HO Phthalo Blue Red Shade (PB15) on Canson XL

Similar to Pyrrol Scarlet, as expected, though I had more trouble making it neutral. The mixes seem a bit more purpley, though the unmixed PR188 color does not look cooler to me than Pyrrol Scarlet.

Perylene Maroon (PR179)

Perylene Maroon + Phthalo Blue Red Shade
Daler Rowney Artist Perylene Maroon (PR179) + Daniel Smith Phthalo Blue Red Shade (PB15:6) on Canson XL paper

Quite an even gray is possible with this mix, a bit on the warm side perhaps.

Deep Scarlet (PR175)

HO Phthalo Blue Red Shade (PB15) + DS Deep Scarlet (PR175) on Canson XL

Really similar to Perylene Maroon

Pyrrole Rubin (PR264)

HO Phthalo Blue Red Shade (PB15) + HO Pyrrole Rubin (PR264) on Canson XL

Muted violets.

Quin Rose (PV19)

Quin Rose + Phthalo Blue Red Shade
Da Vinci Red Rose Deep (PV19) + Daniel Smith Phthalo Blue Red Shade (PB15:6) on Canson XL paper

Fantastic purples.

Phthalo Green (PG7)

DV Phthalo Green (PG7) + HO Phthalo Blue Red Shade (PB15:1) on Arches CP

Teals, similar to those with PBGS but slightly more muted.

Monte Amiata Natural Sienna (PBr7)

Phthalo Blue Red Shade (PB15) + MANS on Canson XL

These tans don’t quite get green.

Raw Sienna (PBr7)

Phthalo Blue Red Shade (PB15) + DV Raw Sienna (PBr7) on Canson XL

Tans and grays.

Quinacridone Burnt Orange (PO48)

DS Quinacridone Burnt Orange (PO48) + Holbein Phthalo Blue Red Shade (PB15) on Canson XL

Transparent Red Oxide

Da Vinci Burnt Sienna Deep (PR101) + Holbein Phthalo Blue Red Shade (PB15) on Canson XL
DS Transparent Red Oxide (PR101) + Holbein Phthalo Blue Red Shade (PB15) on Canson XL

What Others Say

Phthalo Blue Red Shade: This color is unusual. It dries much duller than expected both when used alone and when mixed with other colors, especially pinks and reds. Because of this, it is harder to use than my other blues, as I often forget to compensate for this more dull effect. And, to make it even harder, the dullness appears at all saturation levels. But, I still found myself reaching for it, especially to mix with white gouache. When combined with white the dullness isn’t as much of an issue, and it became a really nice color to use in shadows and as a wash over base colors to create my new favorite canyon wall effects. 

Claire Giordano, Fall in the Southwest: Favorite Colors

The green shade does mix a nice clean green, but personally I don’t have much need for clean greens. I tend to want them to be a bit more olive-leaning. I also find that I prefer the way that the Phthalo Blue Red Shade mixes with the other colors in my palette. I tend to have both Indian Red and Light Red Oxide in my palette, and I really do like the different grays I can mix.

Jay Nathan, Phthalo Blue Red or Green Shade? – Which Do I Use and Why?

My Review of Phthalo Blue Red Shade

I ignored this shade for a long time; it’s so close to PBGS, which was my first and most beloved primary cyan, that I figured I didn’t need to bother with it. But after doing the Blue Sky Showdown and realizing how great it was in dilute as a blue sky color, I added it to my palette, and I find myself reaching for it more and more!

In addition to making a nice daytime sky color on its own, PBRS also gets really dark, making it a good night sky color. It’s even better when mixed with magenta or purple to make a deep, dark blue-purple.

I used Daniel Smith’s PBRS and Schmincke Horadam’s Purple Magenta (PR122) to form the dark purple-blue sky in “Milky Way Delicate Arch”, painted in Feburary 2022 from a tutorial inWilderness Watercolor Landscapes by Kolbie Blume.

One of the things I love about it as a sky color is that it’s not granulating, like most of the recommended sky blues (Ultramarine, Cobalt, Cerulean). I like clear, flat skies with as little texture as possible.

Green Shade is closer to primary cyan and is brighter, which is why I use it on my Neon Palette, but the slightly muted shade of PBRS is more convenient for a plein air or landscape palette, because of its great sky colors and its tendency to mix more muted, naturalistic greens.

On my palette? It’s cycled in and out, typically swapping with the Green Shade.

Favorite version: Da Vinci and Holbein are both good.

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