Does Blue and Green Make Yellow? The Mix Goes Muddy Teal

Blue and green do not make yellow. In additive RGB light, the W3C CSS Color Module Level 3 keyword table sets yellow at red 255, green 255 and blue 0, and sets aqua, later listed as cyan, at red 0, green 255 and blue 255. In subtractive paint, Golden Artist Colors' mixing guide combines Phthalo Blue (Green Shade) and Phthalo Green (Blue Shade) in a 1:1 ratio and names the result turquoise. The worst realistic outcome on a student palette is a darker teal that keeps losing lightness as more blue or green goes in. The pile does not brighten into yellow.

The reporting limit is published standards and manufacturer spec sheets. A spectrophotometer reading of one classroom tube is not in the file. The route a mixer can still run is to name the color model, read the Color Index on the tube, mix a card at a documented ratio, and let the film dry before judging it.

What color does blue and green light make?

Blue light plus green light makes cyan. The International Electrotechnical Commission's IEC 61966-2-1 standard defines the default RGB colour space sRGB. The W3C CSS Color Module Level 3 states that all CSS RGB colors are specified in that space, and that the 8-bit integer 255 corresponds to 100 percent of a channel. Full green plus full blue with red at 0 is aqua: red 0, green 255, blue 255. CSS Color Module Level 4 keeps those coordinates and treats cyan as the same sRGB point.

Yellow on a display is the other pairing. CSS Color 3 lists the keyword yellow as hex #FFFF00, decimal red 255, green 255, blue 0. Red on, green on, blue off. Stephen Westland, Professor of Colour Science and Technology at the University of Leeds School of Design, records the additive overlaps in that order on Colourchat: red plus green yields yellow, red plus blue yields magenta, green plus blue yields cyan. The overlap is coincident light. A spectroradiometer on the yellow patch still finds the red and green emissions.

CSS Color Module Level 4, a W3C Candidate Recommendation Draft dated 1 September 2026, reports sRGB yellow as lab(97.607% −15.753 93.388). CSS Lab is referenced to CIE illuminant D50, the ICC connection-space white. sRGB itself, in IEC 61966-2-1 and in the CSS Color 4 primary table, uses D65, with red chromaticity x 0.640, y 0.330, green x 0.300, y 0.600, blue x 0.150, y 0.060, and white x 0.3127, y 0.3290. A Lab number computed under D65 is not the CSS Lab number. The two illuminants disagree inside the standards.

What color does blue and green paint make?

Blue paint plus green paint makes a darker blue-green, usually a teal or turquoise, by subtracting more of the spectrum. Golden Artist Colors' current Heavy Body product page for Phthalo Blue (Green Shade), Color Index PB15:3, lists CIE L\* 25.61, a\* 6.98, b\* −18.05, tint strength 71.17. The Heavy Body page for Phthalo Green (Blue Shade), Color Index PG7, lists L\* 26.4, a\* −6.93, b\* −5.36, tint strength 78.54. Both masstones sit in the mid-20s for lightness. Process yellow inks sit near L\* 90. Two dark films mixed together stay dark. They do not climb into the L\* 84–91 band of yellow solids on the same manufacturer's charts.

A retailer technical reprint still circulating for that Phthalo Green (Blue Shade) lists L\* 27.19, a\* −8.89, b\* −4.8. Golden's live page and the reprint disagree by about one L\* unit and about two a\* units. Both describe a dark green-blue masstone. Neither describes yellow.

Golden's mixing guide, "Color Mixing with 8 Curated Acrylic Colors," publishes the ratios a student actually needs:

• Turquoise: 1 part Phthalo Blue (Green Shade) to 1 part Phthalo Green (Blue Shade).
• Bright green: 1 part Phthalo Green to 9 parts Hansa Yellow Medium.
• Permanent green light: 1 part Phthalo Blue (Green Shade) to 10 parts Hansa Yellow Medium.

The 1:1 mix is the blue-and-green experiment. Golden names it turquoise. The 1:9 and 1:10 mixes run the other way: a small amount of phthalo stained into a yellow. The guide states that Phthalo Blue and Phthalo Green are the highest-tinting colors in the set and that Hansa Yellow Medium has very little tinting strength.

A blue pigment absorbs long-wave light. A green pigment absorbs at both ends and reflects a middle band. Combined, they absorb more than either film did alone, so lightness falls. The realistic leftover is a duller teal. Adding still more of one tube to "fix" it is the waste. The pile only gets heavier.

Golden also warns that a transparent acrylic can dry darker once the milky emulsion clears. A wet 1:1 phthalo mix already reads as dark teal. The dry film is darker.

What colors actually make yellow?

Yellow on a screen is red light plus green light, CSS Color 3's yellow keyword at red 255, green 255, blue 0. Spectral yellow light, a narrow band that looks yellow on its own, is a different physical stimulus that can match that appearance. In a talk on yellow, Westland put that band at about 560 to 590 nanometres. The two stimuli can look alike. They are not the same spectrum.

Yellow on a palette is a yellow pigment. Golden's Heavy Body pigment-data chart lists C.P. Cadmium Yellow Light, Color Index PY35, at CIE L\* 89.85, a\* −4.64, b\* 94.6. The Hansa Yellow Opaque product page, Color Index PY74, lists L\* 84.48, a\* 10.79, b\* 91.83. Both b\* coordinates are strongly positive, the yellow side of CIE 1976 L\a\*b\ as defined in ISO/CIE 11664-4. The phthalo masstones have negative b\* values. Crossing from b\* −18 to b\* +94 is not a problem solved with more green.

The spectral reason is an absorption edge. Cadmium sulfide, the semiconductor behind PY35, has a direct band gap of 2.42 eV, corresponding to 512 nanometres at room temperature, as reported in the analytical literature on CdS yellow pigments. Below that edge the crystal absorbs; above it, reflectance rises through the long-wave visible. A yellow film does not reflect only the 560–590 nm band.

Print treats yellow as a primary ink. ISO 2846-1:2017, the sheet-fed and heat-set offset ink colour standard, sets process yellow on the specified proofing stock at L\* 91.0, a\* −5.1, b\* 95.0, measured M1, 0°:45°, illuminant D50, 2° observer, with a ΔE\*ab tolerance of 4.0, at some ink-film thickness in the 0.7 to 1.1 micrometre range for oxidation-drying yellow. That is a yellow ink film, not a blue-green overprint.

Westland has spent years correcting the schoolroom claim that red, yellow and blue cannot be mixed from other colors and that every other color can be mixed from them. "None of that is true," he told the Leeds Institute of Textiles and Colour. Yellow can be red-plus-green light. Yellow can also be a subtractive primary that blue-green paint will not reconstruct. The error is using one as a recipe for the other.

How RGB light, paint, and CMYK print treat blue, green, and yellow

RGB light, tube paint, and CMYK printing do not share a recipe for yellow.

| Property | Additive RGB light | Subtractive paint | CMYK printing | | --- | --- | --- | --- | | Primaries | Red, green, blue | The pigments in the tubes; mixing sets often run a magenta, a yellow, and a cyan-leaning blue | Cyan, magenta, yellow, plus black | | Blue + green | Cyan (CSS aqua: R 0, G 255, B 255) | Darker teal; Golden's 1:1 phthalo mix is named turquoise | Not a process pair. Process blue is cyan+magenta; process green is cyan+yellow | | How yellow is made | Red 255 + green 255, blue 0 (CSS Color 3) | A yellow pigment such as PY35 or PY74 | Process yellow ink, a primary | | CIE Lab for a yellow solid | CSS Color 4 sRGB yellow: L\* 97.607, a\* −15.753, b\* 93.388 (D50 Lab) | Golden Cadmium Yellow Light: L\* 89.85, a\* −4.64, b\* 94.6 | ISO 2846-1:2017 yellow: L\* 91.0, a\* −5.1, b\* 95.0 (D50, 2°, M1) | | Realistic failure if the RGB rule is applied here | A cyan screen where yellow was wanted | A muddy teal and a wasted phthalo tube | A cyan-green overprint where a yellow plate was needed |

The Lab row should not be averaged. ISO 2846-1:2017's yellow, L\* 91.0, a\* −5.1, b\* 95.0, is a laboratory print on specified proofing stock. Huber Group's tabulation of ISO 12647-2:2004 process solids on paper types 1 and 2 lists yellow at L\* 89, a\* −5, b\* 93. Heidelberger Druckmaschinen's 2014 presentation of ISO 12647-2:2013 PC1 premium coated, white backing, lists yellow at L\* 89, a\* −4, b\* 93. The a\* coordinate moves by one unit between those print-control tables. L\* sits two points below the ISO 2846-1 ink aim. None of those triples is the CSS Color 4 display yellow at L\* 97.607.

CMYK is how a press lays color down. Cyan ink absorbs red, magenta absorbs green, yellow absorbs blue. Green on the press is cyan plus yellow. Blue is cyan plus magenta. There is no instruction that puts blue and green down to get yellow.

Why the same mix looks different on a screen and on paper

A CSS yellow square is emitted sRGB light, often judged against D65. A paper yellow is reflected light, filtered by pigment, binder, stock, and lamp. IEC 61966-2-1's mapping of integer 255 to full scale does not describe a dried acrylic film. Golden's Lab values are spectrophotometer readings of paint. ISO 2846-1's are readings of ink on APCO II/II proofing paper under D50.

CSS Lab for sRGB yellow is a D50 figure. sRGB primaries are D65. Offset solids in ISO 2846-1 and ISO 12647-2 are D50. Two yellows that match under D50 can split under a cool LED. ISO/CIE 11664-4's L\a\*b\ space compares samples under a named illuminant and observer. If the illuminant is not named, the triple is not a fact a later reader can check.

Drying is the split that costs paint. Golden's mixing guide describes the emulsion as milky while wet and clear after the water leaves. Transparent phthalos shift darker. Matching a screen cyan on a wet palette, then returning to a teal, tempts a mixer to add yellow to warm it. That addition makes an olive: a grey-green lump that cannot pass as yellow and cannot be separated back into the two tubes. That olive is the worst realistic outcome.

How to test a blue-and-green mix without wasting a tube

Golden's exercises start with a palette knife, a white surface, and labeled ratios. Aimed at this query, the sequence is:

1. Read the Color Index name on each tube. PB15 or PB15:3 is a phthalo blue. PG7 is a phthalo green. PY35 or PY74 is a yellow. A tube labeled only "blue" or "green" is not evidence.
2. Mix 1 part Phthalo Blue GS with 1 part Phthalo Green BS on a white card, pea-sized, Golden's turquoise ratio. Spread a masstone next to a thin scrape so undertone is visible.
3. Lay a yellow masstone beside it without combining them. Cadmium Yellow Light or Hansa Yellow Opaque from the same line will do.
4. Let the acrylic film dry. Golden flags the darkening of transparent colors as the emulsion clears. The dry teal is the result that counts.
5. If yellow is the target, squeeze the yellow tube instead of adding more blue or green. Extra phthalo will not raise L\* into the 84–91 band of those yellow spec sheets.

The 1:9 and 1:10 recipes in the same guide make a green from yellow. They show the phthalo as the stain and the yellow as the bulk. Verification is whether the dry card looks like the teal Golden named, or like the yellow on the spec sheet.

FAQ

Does blue and green paint make yellow?

Blue and green paint does not make yellow. Golden Artist Colors' mixing guide mixes Phthalo Blue (Green Shade) and Phthalo Green (Blue Shade) in equal parts and names the result turquoise. Both masstones sit near L\* 26 on Golden's spec sheets, far below a yellow solid near L\* 90. The leftover is a darker teal.

What color do blue and green make together?

In RGB light they make cyan. CSS Color Module Level 3 sets aqua, later listed as cyan, at red 0, green 255 and blue 255. In paint they make a darker blue-green. Golden's 1:1 phthalo recipe is turquoise. The two answers disagree because one adds light and the other subtracts it. Naming the medium is the first step.

What colors make yellow?

On a display, red light plus green light. CSS Color 3's yellow keyword is red 255, green 255, blue 0. On a palette or a press, a yellow pigment or process yellow ink. ISO 2846-1:2017 sets that ink at L\* 91.0, a\* −5.1, b\* 95.0 under D50. Blue and green are not on either recipe.

What color do blue, green, and yellow make?

A darker, often olive or muddy green, because the yellow is stained by two strong absorbers. Golden's guide already treats phthalos as high-tinting and yellow as weak: 1 part Phthalo Green to 9 parts Hansa Yellow Medium is a bright green, not a yellow. Adding blue on top of that green only deepens it.

Why does the same mix look different on a screen and on paper?

A screen yellow is emitted sRGB light, CSS integers 255, 255, 0, often judged against D65. A paper yellow is reflected ink or paint, measured in Lab under D50 in ISO 2846-1 and ISO 12647-2. CSS Color 4's Lab for sRGB yellow, L\* 97.607, is lighter than those printed solids. Wet acrylic also dries darker as the emulsion clears.