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.

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

DV Green Gold (PY129) + HO Phthalo Blue Red Shade (PB15:1) on Arches

Much more muted greens than the very bright ones with RGG and PBGS. There’s a Sap Greenish look to the dark one tilted toward Rich Green Gold. I’ve never seen this suggested as a Sap Green alternative formula, but I think this works!

Transparent Pyrrol Orange

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 find it. Orange-browns on the TPO side, and neutralized warm blue-blacks on the PBRS side.

Perylene Maroon

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

Deep Scarlet + Phthalo Blue Red Shade
DS Deep Scarlet (PR175) + Holbein Phthalo Blue Red Shade (PB15:1)

Really similar to Perylene Maroon

Quin Rose

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

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

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

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

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 without as little texture as possible.

On my palette? It’s cycled in and out, typically swapping with the Green Shade. Green Shade is a better primary bold which is why I use it on my Neon Palette and typically on my main palette, but the slightly muted shade of PBRS is more convenient to work with and great for desert sky settings.

Favorite version: Da Vinci and Holbein are both good.

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