dye class
Food tar colors (food coloring)
Also known as: food coloring, tar color / tar dye
A collective term for petroleum-derived synthetic colourants that may be used in food (12 designated in Japan as of 2025). Most are water-soluble dyes with sulfonic acid groups; in an acidic bath they dye wool, silk and nylon, but not cotton.
The food additive rules and assessments shown here concern eating the colours as food, not using them for dyeing.
Theme: Drawn by charge
Claims and evidence (28)
The limitations noted for some sources are recorded in Japanese only — see the Japanese edition.
Food tar colors (food coloring) ・typeStates that this term covers 12 petroleum-derived synthetic colorants designated by the Minister of Health, Labour and Welfare under the Food Sanitation Act (Food Red Nos. 2, 3, 40, 102, 104, 105, 106; Yellow Nos. 4, 5; Green No. 3; Blue Nos. 1, 2).contextual
Scope: As of May 2025, in Japan
Gives a table pairing the Japanese and English names of the 12 dyes and states they were designated additives as of May 2025.
Source: 食用タール色素について（食品衛生基準審議会 添加物部会 資料４） （消費者庁 食品衛生基準審査課, 2025） ・3頁「日本における食用タール色素の取扱い」の一覧表 ・institutional summary ・ checked against the source by AI
institutional summary ・ 
checked against the source by AILists the same 12 Japanese dye names and also states which foods they may not be used in (e.g. kasutera sponge cake, kinako, salted fish products).
Source: 用途別 主な食品添加物：着色料 （東京都保健医療局） ・「食用タール系色素」の項 ・institutional summary ・ checked against the source by AI
Context: Confirms the current designated count while noting that some numbers in the sequence are missing because colours found unsafe or unused were removed over time.
Source: 食品中の着色料について （大阪健康安全基盤研究所, 2023） ・冒頭「食用タール色素とは」の段落 ・institutional summary ・ checked against the source by AI
Food tar colors (food coloring) ・propertyStates that the official structural formulas for Red Nos. 2, 40, 102, 106, Yellow Nos. 4, 5, Green No. 3 and Blue Nos. 1, 2 show sodium sulfonate (SO3Na) groups, while Red Nos. 3, 104 and 105 show no sulfonate group and instead show halogen substituents (bromine/iodine) and a carboxylate (COONa) group.contextual
Scope: As shown in the official MHLW analytical-method structural diagrams
The structural diagrams for 9 of the 12 dyes (Red Nos. 2, 40, 102, 106, Yellow Nos. 4, 5, Green No. 3, Blue Nos. 1, 2) show SO3Na labels; Red Nos. 3, 104 and 105 show no SO3Na, instead showing bromine/iodine substituents and a COONa group.
Source: 着色料：食用タール色素（食品添加物分析法） （厚生労働省, 2023） ・3〜4頁「食用タール色素／Food Tar Colors」構造式一覧（頁ノンブルはPDF内表示、pdftoppmで頁画像を出して確認） ・standard definition ・ checked against the source by AI
standard definition ・ Food tar colors (food coloring) ・typeStates that the tar-type food dyes currently in use are what Katayama (1974) calls acid colorants (酸性色素) that form a chemical bond with protein, with an exception noted for some xanthene-type dyes, which bond physically in a colloidal state instead. Whether this is formally the same class as the textile acid dye is not confirmed by the source.contextual
Scope: As described in a 1974 source
Groups the tar colors in current use under the single label "acid colorant," explaining their bond to protein as chemical in nature — while adding that some xanthene-type dyes are an exception, merely clinging on physically as colloidal particles rather than bonding chemically.
Source: 食用色素の化学 （片山脩, 1974） ・誌面624頁「VIII. タール色素の性質と使用上の問題点」3.染着力の項 ・textbook ・ checked against the source by AI
textbook ・ States plainly that food colorings are classified as a subset of Acid Dyes.
Source: Using Food Coloring as a Textile Dye for Protein Fibers （Paula E. Burch, 2008） ・見出し「Using Food Coloring as a Textile Dye for Protein Fibers」の第1段落 ・practitioner's record ・ checked against the source by AI
practitioner's record ・ Food tar colors (food coloring) ・requiresStates that azo-type food dyes require heating under strongly acidic conditions to bind adequately, whereas xanthene-type dyes (excluding Red No. 106) have a strong affinity for protein and bind particularly well even under weakly acidic conditions.contextual
Scope: Contrasting azo-type and xanthene-type (excluding Red No. 106) dyes, as of a 1974 source
Contrasts the two groups: xanthene-type dyes (Red No. 106 aside) are said to draw protein to themselves readily and dye well even under only mildly acidic conditions, whereas azo-type dyes are said to need both strong acid and applied heat, or the dyeing falls short.
Source: 食用色素の化学 （片山脩, 1974） ・誌面624頁「3.染着力」の項 ・textbook ・ checked against the source by AI
Food Red No. 106 ("Acid Red") is a type of Food tar colors (food coloring)contextual
Records "Acid Red" as an alternate name for Food Red No. 106.
Source: 着色料：食用タール色素（食品添加物分析法） （厚生労働省, 2023） ・4頁「食用赤色106号」の項（別名の記載。頁ノンブルはpdftoppmで頁画像を出して確認） ・standard definition ・ checked against the source by AI
Labels Red No. 106 "Acid Red" and states it is the one xanthene-type dye that bonds chemically with protein (unlike the others in that group).
Source: 食用色素の化学 （片山脩, 1974） ・誌面623頁「図10 食用赤色106号(アシッドレッド)」と624頁「3.染着力」の項 ・textbook ・ checked against the source by AI
Allura Red AC (FD&C Red No. 40) is a type of Food tar colors (food coloring)contextual
States it belongs to the class of monoazo dyes and lists Allura Red AC, CI Food Red 17, CI 16035 (Colour Index, 1975), and FD&C Red No. 40 among its synonyms.
Source: Allura Red AC — Chemical and Technical Assessment (CTA) （Barrows, J.N.; Wallin, H.（JECFA 第82回会合）, 2016） ・2. Description; Table 1 “Synonyms”欄 ・analytical ・ checked against the source by AI
analytical ・ Lists allura red (red dye #40) with Colour Index number 16035, matching the number given in the FAO technical assessment.
Source: Using Food Coloring as a Textile Dye for Protein Fibers （Paula E. Burch, 2008） ・色素名・Colour Index番号・E/INS番号の対照表 ・practitioner's record ・ checked against the source by AI
Tartrazine (Food Yellow No. 4) is a type of Food tar colors (food coloring)contextual
Scope: The production-share figure is from Table 1's survey period (Showa 45.4-46.3, i.e. April 1970-March 1971); the source article itself was published in 1974
Describes Yellow No. 4's production route (condensation of ethyl oxalacetate with phenylhydrazine-p-sulfonic acid, then coupling with the diazonium salt of sulfanilic acid) and states it had the largest production share (41%) among tar colors.
Source: 食用色素の化学 （片山脩, 1974） ・誌面621頁「II. アゾ系食用色素」黄色4号の項 ・textbook ・ checked against the source by AI
Amaranth (Food Red No. 2) is a type of Food tar colors (food coloring)contextual
Describes Red No. 2's production route (diazotized naphthionic acid coupled with 2-naphthol-3,6-disulfonic acid), its solubility (readily soluble in water/propylene glycol, poorly soluble in ethanol, insoluble in oils/fats), and its vulnerability to oxidation, reduction and fading in the presence of copper or iron.
Source: 食用色素の化学 （片山脩, 1974） ・誌面621頁「II. アゾ系食用色素」赤色2号の項（頁ノンブルはpdftoppmで頁画像を出して確認。以下同様） ・textbook ・ checked against the source by AI
Ponceau 4R / New Coccine (Food Red No. 102) is a type of Food tar colors (food coloring)contextual
Scope: Usage-volume statement is as of 1974
States it is weak against heat, oxidation, reduction and alkali, that it has the largest usage among red-series dyes, and lists foods it is used in.
Source: 食用色素の化学 （片山脩, 1974） ・誌面621頁「図2 食用赤色102号」周辺の本文 ・textbook ・ checked against the source by AI
Brilliant Blue FCF (Food Blue No. 1) is a type of Food tar colors (food coloring)contextual
Describes the production route (condensation then oxidation with sodium dichromate or lead peroxide) and states it is strongly resistant to light, heat, salt, oxidation, reduction and alkali.
Source: 食用色素の化学 （片山脩, 1974） ・誌面622頁「図6 食用青色1号」周辺の本文 ・textbook ・ checked against the source by AI
Lists brilliant blue FCF (blue #1) with Colour Index number 42090.
Source: Using Food Coloring as a Textile Dye for Protein Fibers （Paula E. Burch, 2008） ・色素名・Colour Index番号の対照表 ・practitioner's record ・ checked against the source by AI
Erythrosine (Food Red No. 3) is a type of Food tar colors (food coloring)contextual
States Red No. 3 is made by iodizing purified "フロルエッセン" (the source's own term, distinct from tetrachlorofluorescein used for Red No. 104/105), is unstable to light and acid but has excellent heat- and reduction-resistance suiting baked goods and fermented foods, and has good protein affinity but is hard to use in beverages or candy because it forms an insoluble dye-acid precipitate on contact with acid.
Source: 食用色素の化学 （片山脩, 1974） ・誌面622頁「IV. キサンテン系食用色素」赤色3号の項 ・textbook ・ checked against the source by AI
Lists erythrosine (red #3) with Colour Index number 45430.
Source: Using Food Coloring as a Textile Dye for Protein Fibers （Paula E. Burch, 2008） ・色素名・Colour Index番号の対照表 ・practitioner's record ・ checked against the source by AI
Indigotine / Indigo Carmine (Food Blue No. 2) is a type of Food tar colors (food coloring)contextual
States Blue No. 2 is the only indigoid-class dye, describes its production (sulfonation of indigo with concentrated sulfuric acid, then neutralization and salting-out), and notes it is very weak against light and heat, limiting its use and leading to frequent blending with other dyes.
Source: 食用色素の化学 （片山脩, 1974） ・誌面623頁「V. インジゴイド系食用色素」の項 ・textbook ・ checked against the source by AI
Lists indigotine (blue #2) with Colour Index number 73015.
Source: Using Food Coloring as a Textile Dye for Protein Fibers （Paula E. Burch, 2008） ・色素名・Colour Index番号の対照表 ・practitioner's record ・ checked against the source by AI
Food tar colors (food coloring) is applicable to woolcontextual
Scope: In the context of home dyeing with food coloring or drink mix
States it can be used only to dye protein fibres — wool, silk, and sometimes nylon.
Source: Using Food Coloring as a Textile Dye for Protein Fibers （Paula E. Burch, 2008） ・本文「They can be used to dye protein fibers only: that is, wool, silk, and also sometimes nylon.」 ・practitioner's record ・ checked against the source by AI
Reports that 100% wool yarn dyed vividly using food coloring and vinegar in the author's own trial.
Source: 食用色素で毛糸を手染めしたら、思ったよりあっさり染まった （ブログ「ニュージーランドめし」筆者（ハンドルネーム tufui57）, 2019） ・本文「ウール100%の毛糸」の段落 ・practitioner's record ・ checked against the source by AI
Food tar colors (food coloring) is applicable to silkcontextual
Scope: In the context of home dyeing
Lists silk alongside wool as a fibre that can be dyed.
Source: Using Food Coloring as a Textile Dye for Protein Fibers （Paula E. Burch, 2008） ・本文「They can be used to dye protein fibers only: that is, wool, silk...」 ・practitioner's record ・ checked against the source by AI
Food tar colors (food coloring) is applicable to nyloncontextual
States nylon dyes because its chemical structure somewhat resembles wool's.
Source: Using Food Coloring as a Textile Dye for Protein Fibers （Paula E. Burch, 2008） ・本文「nylon...because the chemical structure of nylon somewhat resembles that of wool」 ・practitioner's record ・ checked against the source by AI
Context: Notes that some nylon garments are treated with Teflon or other coatings that prevent dyeing.
Source: How can I tie dye with Kool-aid or food coloring? (Tie Dye with Kool-Aid) （Paula E. Burch, 2003） ・本文「Some nylon garments are treated with Teflon or other coatings, which prevent dyeing.」 ・practitioner's record ・ checked against the source by AI
Food tar colors (food coloring) fell out of use, reportedly because of cottoncontextual
States food colorings have no way to permanently attach to cotton and will wash out leaving at most a pale stain, and that they cannot be used on other plant fibres (linen, rayon) or synthetics other than nylon (acrylic, polyester).
Source: Using Food Coloring as a Textile Dye for Protein Fibers （Paula E. Burch, 2008） ・本文「Food colorings lack any way to permanently attach to cotton, so they will just wash out, leaving at most a pale stain」 ・practitioner's record ・ checked against the source by AI
States food coloring on cotton is a stain rather than a dye, and cannot be made permanent.
Source: How can I tie dye with Kool-aid or food coloring? (Tie Dye with Kool-Aid) （Paula E. Burch, 2003） ・本文「Food coloring on cotton is a stain, not a dye, and will not last. You can't make it permanent.」 ・practitioner's record ・ checked against the source by AI
Food tar colors (food coloring) bonds via Dyeing via ionic bondingcontextual
States its attachment to protein fibres (and nylon) takes the form of ionic and hydrogen bonds.
Source: How can I tie dye with Kool-aid or food coloring? (Tie Dye with Kool-Aid) （Paula E. Burch, 2003） ・本文「Its attachments to protein fibers...are in the form of ionic and hydrogen bonds.」 ・practitioner's record ・ checked against the source by AI
Food tar colors (food coloring) requires vinegarcontextual
Scope: As explained on Paula Burch's page on home dyeing with food colouring and drink mix. The same page limits what to dye to wool, silk and nylon, and says not to use cotton or synthetics other than nylon
States citric acid in drink mix supplies the needed acid, while plain food coloring requires pre-soaking in white vinegar.
Source: How can I tie dye with Kool-aid or food coloring? (Tie Dye with Kool-Aid) （Paula E. Burch, 2003） ・本文「The acid required for the dye reaction is provided...in the form of citric acid...If you use plain food coloring drops, you'll need to pre-soak your fabric or yarn in some plain white vinegar」 ・practitioner's record ・ checked against the source by AI
Food tar colors (food coloring) ・requiresStates that heat is required, and that room-temperature dyeing usually produces much less washfast results.contextual
States heat is required and room-temperature dyeing yields much less washfast results.
Source: Using Food Coloring as a Textile Dye for Protein Fibers （Paula E. Burch, 2008） ・本文「Heat is required; room-temperature dyeing will usually produce much less washfast results.」 ・practitioner's record ・ checked against the source by AI
Food tar colors (food coloring) ・mechanismDescribes a procedure for dyeing wool, silk or nylon with unsweetened drink mix or food coloring: (1) pre-dampen the fibre with water (plus vinegar if using plain food coloring, or plain water if the mix already contains an acid), (2) sprinkle on dye and cover the dish, (3) heat (e.g. in a microwave) until the material is hot, (4) let it cool gradually to room temperature, (5) rinse in cool water.contextual
Scope: The source breaks the procedure into more headed sub-steps (from "What to dye" to "Laundering"); this summarises only the core dyeing steps into 5 stages
Under separate headings, describes pre-soaking in vinegar or acid-containing mix, sprinkling and covering the dye, microwave heating, gradual cooling, and cold-water rinsing.
Source: How can I tie dye with Kool-aid or food coloring? (Tie Dye with Kool-Aid) （Paula E. Burch, 2003） ・「Project」以降の各見出し(Pre-soak your fiber / Add dye / Cover the dish / Heat in the microwave / Allow to cool / Rinse) ・practitioner's record ・ checked against the source by AI
PAAS Easter Egg Dye Kit is a type of Food tar colors (food coloring)contextual
States the PAAS package is labelled "pure food-color kit."
Source: Dyeing Yarn With Easter Egg Dyes （Sonja Record（Sonja Kathleen Contemporary Knitting）） ・「Choosing and Mixing the Dye」の段落「actually says 'pure food-color kit' right on the package」 ・practitioner's record ・ checked against the source by AI
States that seasonally available Easter egg dyes marketed for children are also food colors.
Source: Using Food Coloring as a Textile Dye for Protein Fibers （Paula E. Burch, 2008） ・「How can I buy food coloring?」の項「The seasonally available Easter egg dyes that are marketed for children are food colors, as well.」 ・practitioner's record ・ checked against the source by AI
Food tar colors (food coloring) ・mechanismDescribes a 5-step procedure for hand-dyeing 100% wool yarn with food coloring: (1) soak the yarn for about 5 minutes in 1 cup of water with 2 tablespoons of vinegar, (2) meanwhile dissolve food coloring in water, (3) dip the yarn in the dye solution, (4) wrap the yarn in plastic wrap and microwave it (800W for 3 minutes per 100g), (5) once cool, wash with water mixed with dish soap until no more colour runs out.contextual
Gives the same 5 numbered steps (soak in vinegar water, dissolve dye, dip yarn, wrap and microwave at 800W for 3 minutes, wash with dish soap).
Source: 食用色素で毛糸を手染めしたら、思ったよりあっさり染まった （ブログ「ニュージーランドめし」筆者（ハンドルネーム tufui57）, 2019） ・本文の番号付き手順１〜５ ・practitioner's record ・ checked against the source by AI
Food tar colors (food coloring) ・propertyStates that yarn blended with acrylic (e.g. 20% acrylic) can also be tried, but since acrylic and other synthetic fibres do not take this dye method, the result is expected to be mottled, with only the wool portion dyeing. Also reports that the yarn tried came out less prone to bleeding colour than the author had expected.contextual
Scope: Based on the author's own small-scale trial
States acrylic-blend yarn can be used but the acrylic portion won't dye (leading to a mottled result), and that the yarn tried dyed more easily than expected and did not bleed.
Source: 食用色素で毛糸を手染めしたら、思ったよりあっさり染まった （ブログ「ニュージーランドめし」筆者（ハンドルネーム tufui57）, 2019） ・本文「使う毛糸は必ずしもウール100%でなくてもいい...アクリルやポリエステルなどの合成繊維はこの方法では染まりません」および「思ったよりあっさりと染まった上に、色落ちしません」の段落 ・practitioner's record ・ checked against the source by AI
Food tar colors (food coloring) ・regulationStates that in April 2025 the US Department of Health and Human Services (HHS) and FDA announced a series of measures to phase petroleum-derived synthetic colorants out of the US food supply by the end of 2026, and that no information has been confirmed of major countries other than the US (Canada, the EU, Australia, etc.) changing their handling of these colorants either.contextual
Scope: US regulatory developments and the status in major countries other than the US (Canada, EU, Australia), as of May 2025
Introduces the HHS/FDA announcement of 22 April 2025 on phasing out synthetic colorants by end-2026, and states no information on changed handling has been confirmed for major countries other than the US.
Source: 食用タール色素について（食品衛生基準審議会 添加物部会 資料４） （消費者庁 食品衛生基準審査課, 2025） ・1頁「合成着色料に関するFDA公表資料の概要」、3頁「米国以外の主要国において、食用タール色素の取扱いを変更する等の情報は確認できていない。」 ・institutional summary ・ checked against the source by AI
Food tar colors (food coloring) ・propertyStates that food-additive safety is ensured by a system in which the Food Safety Commission conducts a risk assessment and sets an ADI (Acceptable Daily Intake), and the Ministry of Health, Labour and Welfare then permits use only where it poses no risk to human health.contextual
Explains the two-stage system: risk assessment and ADI-setting by the Food Safety Commission, followed by use authorization by the Ministry of Health, Labour and Welfare.
Source: 食品表示の内容を正しく理解するための「食品添加物表示に関するマメ知識」 （消費者庁, 2021） ・「6 食品添加物って安全なの？」の項 ・institutional summary ・ checked against the source by AI
Food tar colors (food coloring) ・used inCites tar colors as an example of a food additive also used at home, used to colour foods such as sekihan (red rice) and beni-shoga (red pickled ginger).contextual
Lists tar colors (Red No. 2, Yellow No. 4, etc.) and states they are used to colour sekihan and beni-shoga.
Source: 食品表示の内容を正しく理解するための「食品添加物表示に関するマメ知識」 （消費者庁, 2021） ・「家庭でも使用されている食品添加物」の表 ・institutional summary ・ checked against the source by AI
Food tar colors (food coloring) ・propertyA 1974 source states that of 24 tar colors permitted in 1964, colors were progressively banned over concerns about toxicity, leaving 11 (Red Nos. 2, 3, 102, 104, 105, 106; Yellow Nos. 4, 5; Green No. 3; Blue Nos. 1, 2) as of that writing. The current (2025) list of 12 includes those 11 plus Food Red No. 40 (Allura Red AC).contextual
Scope: Comparing a 1974 account with a 2025 listing
States in its opening paragraph that of 24 tar colors permitted in 1964, colors were banned progressively between 1965 and 1972 over carcinogenicity concerns, leaving "the 11 described below"; counting the dyes actually given individual treatment in the body (sections II azo through V indigoid) yields exactly those 11 (Red Nos. 2, 3, 102, 104, 105, 106; Yellow Nos. 4, 5; Green No. 3; Blue Nos. 1, 2).
Source: 食用色素の化学 （片山脩, 1974） ・誌面620頁冒頭の段落(24種→11種の経緯)、および本文II〜V章で個別に扱われる11色素の一覧(誌面620〜623頁) ・textbook ・ checked against the source by AI
Context: The current 12-dye list includes Food Red No. 40 in addition to the 11 named in the 1974 source.
Source: 食用タール色素について（食品衛生基準審議会 添加物部会 資料４） （消費者庁 食品衛生基準審査課, 2025） ・3頁の12種一覧表 ・institutional summary ・ checked against the source by AI
Food tar colors (food coloring) ・propertyThe Ministry of Health, Labour and Welfare's official analytical method (appended Table 2) gives the Colour Index number for each of the 12 designated food tar dyes: Red No.2 16185, Red No.3 45430, Red No.40 16035, Red No.102 16255, Red No.104 45410, Red No.105 45440, Red No.106 45100, Yellow No.4 19140, Yellow No.5 15985, Green No.3 42053, Blue No.1 42090, Blue No.2 73015. The same table also lists Rf values and CI numbers for several non-designated dyes shown for comparison (e.g. Ponceau 3R, Orange II).contextual
Scope: The Ministry of Health, Labour and Welfare's official food-additive analytical method, appended Table 2 (revised 2008, consolidated 2023)
Appended Table 2, headed 'Tar Colours (Colour Index)', lists Rf values under four separation conditions alongside each dye's Colour Index number. The left column lists the 12 designated food dyes with their CI numbers as above; the right column lists non-designated dyes (e.g. Ponceau 3R) for comparison.
Source: 着色料：食用タール色素（食品添加物分析法） （厚生労働省, 2023） ・p.13(PDF内表示のノンブル)、注31本文はp.12、注表２「タール色素のRf値」表左列(タール色素とColour Indexの対応) ・standard definition ・ checked against the source by AI
Open questions (5)
Is the "acid colorant" (酸性色素) classification used for food-industry sources formally the same class as the textile "acid dye"?
Katayama (1974) calls food tar dyes "acid colorants" (酸性色素) and Paula Burch explicitly calls food coloring "a subset of Acid Dyes" in English. The two read as saying the same thing, but no source found so far states outright that the Japanese term 酸性色素 and the textile-industry term 酸性染料 are formally the same classification.
Is there a source that directly discusses the safety of skin contact with, or inhalation of, food-dye powder during craft dyeing?
The Consumer Affairs Agency material explains ADI-based (oral-intake) safety evaluation but does not address skin contact or inhalation. Paula Burch warns not to breathe the powder but gives no specific account of health effects.
Do xanthene-type food dyes (e.g. Erythrosine/Red No. 3) dye protein fibres well with weaker acid and less heat than azo-type dyes (e.g. Tartrazine, Allura Red AC)?🧪 testable at home
Katayama (1974) states xanthene-type dyes (excluding Red No. 106) bind especially well under weakly acidic conditions, while azo-type dyes need heating under strong acid. Whether this translates into a noticeable difference in home dyeing (e.g. Kool-Aid dyeing) is not addressed by the sources gathered.
What safety cautions do children's science-education materials that use food dye explicitly state?
A US science-education site (Science Buddies) appears to have a page on a food-dye dyeing experiment, but it could not be retrieved due to bot detection, so its content was not confirmed.
Can food colourings be counted as a subset of acid dyes?
Paula Burch's food-colouring page says "Food Colorings are a subset of the class of dyes known as Acid Dyes", but this is not yet a claim in our records. A Japanese source (Katayama 1974) calls food tar colours "acid colours". No source seen says the two refer to the same class. This underpins the analogy in the closing section of the theme "Drawn by charge".