Colouring Soap Legally: Micas, Oxides, Clays and Botanicals in a CPSR

Colour is why most people buy a handmade soap rather than a supermarket bar, and it is the part of a soap file where makers most often discover a problem. The issue is rarely danger. It is documentation: a colourant bought from a craft supplier, described as soap safe, with no CI number, no specification and no heavy metal data cannot be assessed, which means the bar containing it cannot be concluded safe. Colourants are governed by Annex IV of Regulation (EC) No 1223/2009, a positive list carried into UK law and enforced through the Cosmetic Products Enforcement Regulations 2013, and the entries carry conditions on where and how each may be used.

What follows is the working version for a soap file: how Annex IV and field-of-application restrictions actually bite, why "soap stable" is not a legal term, how to read a mica specification, what oxides and ultramarines do in a high-pH bar, the clay and charcoal questions, botanical colour and its real limits, the heavy-metal data that decides which suppliers are usable, how the label and the may-contain convention work for a shade range, the morphing and bleeding problems that are quality rather than compliance, a worked example of a range that had to be recoloured, and the documentation to send your assessor.

How Annex IV works

Annex IV lists every colourant permitted in cosmetic products in the UK and EU. Each entry gives the colour index number or chemical name, the permitted field of application, any maximum concentration and any other conditions or purity requirements. The structure is the important part: this is a positive list, so a colourant that does not appear is not permitted, and there is no route by which a safety argument or a supplier assurance makes an unlisted pigment usable. Fields of application are expressed in categories that matter in practice. Some colourants are permitted in all cosmetic products. Some are excluded from products applied to mucous membranes, which rules them out for lip and intimate products but allows them in a body soap. Some are restricted to products that come into brief contact with skin and are then rinsed off, which happens to suit soap. And some may not be used in eye products. For soap, which is a rinse off product applied to skin generally, the available list is comfortably wide, which is why colouring soap legally is a documentation exercise rather than a creative constraint.

Soap stable, cosmetic grade and other words that mean nothing

Craft suppliers describe colourants in language designed to be reassuring rather than accurate. Soap stable tells you the colour survives a high pH environment, which is genuinely useful information and says nothing at all about whether the pigment is permitted in cosmetics. Cosmetic grade has no legal definition and is used by suppliers to mean anything from fully specified and certified to probably fine. Skin safe is similar. Natural is irrelevant to Annex IV, which lists some natural pigments and excludes others. The only things that resolve the question are the CI number, which identifies the colourant precisely and lets you find its Annex IV entry, and the specification with a batch certificate of analysis, which confirms purity and heavy metal content. A sensible rule for a maker is that a colourant with a CI number, a specification sheet and a batch certificate goes in the file, and a colourant described with adjectives does not. This single habit removes the most common cause of delay in soap assessments.

Reading a mica specification

Mica is the most misunderstood soap colourant because a mica is not one substance. It is a platelet of mica, CI 77019, coated with one or more pigments, commonly titanium dioxide, CI 77891, for pearl and opacity, iron oxides, CI 77491, 77492 and 77499, for warm tones, and sometimes carmine, ultramarines, chromium oxides, ferric ammonium ferrocyanide (CI 77510) or organic lakes for stronger colour. The legal position of the finished mica is therefore determined by every pigment in the coating, not by the mica substrate. A supplier specification should list each component with its CI number, and that list is what you check against Annex IV. Three practical points follow. Ferric ammonium ferrocyanide, CI 77510 (often sold as Prussian blue or iron blue), is listed in Annex IV for all cosmetic products, including lip products, on condition that it is free from cyanide ions. The US FDA allows it only in externally applied cosmetics and not in lip products (21 CFR 73.2298 and 73.2299), so a maker selling a lip range in the US must recheck the micas. A mica containing a dye that is not Annex IV listed cannot be used, and these do appear in micas sold to the craft and resin market. And micas containing bismuth oxychloride or certain organic lakes often fade or morph in high pH soap, which is a performance rather than a legal matter but tends to be discovered at the same time. Where a mica specification lists only the colour name and a batch number, go back to the supplier or change supplier.

Oxides, ultramarines and what survives soap

The pattern worth absorbing is that the inorganic pigments, oxides, ultramarines, chromium greens and titanium dioxide, are both the most reliable in a pH 10 environment and the least troublesome to document, which is why experienced soap makers build their palettes from them and use micas for shimmer rather than for primary colour. Organic dyes and lakes give brighter and more unusual shades and are the ones most likely to morph during cure, bleed between layers or fade on a sunlit shelf. None of that is a safety issue; it is the reason to run a small test batch and photograph it over eight weeks before committing a season's packaging to a colour.

Clays, charcoal and dual purpose additives

Clays occupy a useful position in soap because they do two jobs. Kaolin, bentonite, French green, rhassoul and Australian clays colour the bar in soft natural tones, add slip, help anchor fragrance and give a pleasant silky feel. The assessment treats them as both colourant and functional additive, and the questions are about specification rather than permission: the mineral identity, the particle size, the heavy metal content, since clays are mined materials and naturally carry trace metals, and the microbiological quality, because clays are not sterile and can carry a significant spore count. For a soap at pH 10 the microbiological point is largely academic, but the same clay in a water based mask is a real issue, and a maker who uses one clay across both product types needs the specification regardless. Activated charcoal is similar, with one documentation trap: used as a colourant it has to meet the Annex IV entry for carbon black, CI 77266, including its Annex IV purity limits (purity > 97 %, total PAH ≤ 500 ppb, benzo(a)pyrene ≤ 5 ppb, and stated heavy-metal caps), so ask the supplier to confirm the grade meets that specification. It is excellent as a colourant, widely used for its adsorbent reputation, and worth buying in a cosmetic specified grade rather than from a horticultural or aquarium supplier, since the source material and activation process determine what else is in it. Rate matters for both: clays and charcoal above around five percent of the batch can make a bar crumbly or drying, which the assessor may note in the directions.

Botanical colour and its real limits

Colouring soap with plants is the oldest route and the least predictable. Indigo, woad, madder root, alkanet, annatto, paprika, turmeric, spirulina, nettle, calendula, alfalfa, cocoa and coffee all give colour, and their legal status depends on the material rather than on the romance. A plant material used as an ingredient of the soap is assessed like any other ingredient, by identity, specification and any known hazards, and several deserve attention: paprika and capsicum extracts are irritants, turmeric stains everything including skin and bath surfaces, alkanet and madder vary enormously by batch, and some botanicals carry photosensitising compounds. The practical limits are quality rather than legal. Botanical colour fades, often dramatically, in sunlight over weeks. It morphs during saponification, with turmeric going orange to tan and spirulina going green to grey. It can bleed between layers. And batch to batch variation makes a consistent brand palette genuinely difficult. Where a maker wants reliable colour with a natural story, clays and oxides are the honest answer, since iron oxides are mineral pigments, and nothing prevents a brand from describing them accurately as such.

Heavy metals, purity and which suppliers are usable

Colourants are the ingredients most likely to carry heavy metal impurities, because oxides and clays are mineral in origin and pigment manufacture can introduce traces of lead, arsenic, mercury, cadmium, antimony and chromium six. Annex IV entries include purity requirements for exactly this reason, and the assessor evaluates trace impurities in the file. For a rinse off soap the exposure is low and the margins are generous, so the assessment usually passes comfortably, provided the data exists. That proviso is the whole issue. Cosmetic pigment suppliers provide specifications with heavy metal limits and batch certificates as standard. Craft, art, resin, candle and horticultural suppliers generally do not, and a pigment with no impurity data cannot be assessed on an assumption of cleanliness. The decision this forces on a maker is straightforward and worth making once: buy colourants only from suppliers serving the cosmetic industry, keep the certificates with the batch records, and the colour section of every future file writes itself. It also future proofs the range against a move into leave on or lip products, where the same data is examined far more closely.

Labelling colour

Colourants appear in the ingredient list by their CI number, written as CI followed by the five digit number, or by their INCI name where they have one, such as Mica or Titanium Dioxide. Under Article 19(1)(g) the ingredient list runs in descending order of weight down to one percent, after which ingredients may be listed in any order, and colourants other than hair colourants may be listed at the end of the list in any order after the other ingredients. That last provision is useful for soap. More useful still is the may contain convention: for decorative cosmetic products marketed in several colour shades, all colourants used across the range (other than hair colourants) may be listed preceded by the words may contain or the symbol +/-, which lets one label serve a whole shade range. Strictly, Article 19(1)(g) offers this to decorative cosmetics sold in several shades, so confirm with your assessor or Responsible Person before relying on it for a soap range; many soap brands print a full ingredient list per bar instead. Every colourant listed must be permitted for the product type concerned. Two further points catch makers out. A colourant used at a tiny level still has to be declared, since there is no de minimis threshold for ingredient listing. And a mica must be declared by its components, so a label reading only Mica for a pigment coated with titanium dioxide and iron oxides is incomplete. Our label and packaging review catches these before a print run.

A worked example: the range that had to be recoloured

A maker with a twelve bar range submits a file for a multiple variant assessment. Ten bars use iron oxides, titanium dioxide, ultramarines and three clays, all bought from a cosmetic supplier with full specifications, and they clear without comment. Two bars use colourants bought from a craft supplier: a neon pink described as soap stable and a bright teal described as cosmetic grade. Neither has a CI number on the packaging or on the supplier's website, and an enquiry establishes that the pink is a fluorescent pigment sold mainly into the resin and nail art market and the teal is a blend whose composition the supplier will not disclose. Neither can be assessed, so neither bar can be concluded safe. The maker replaces the pink with an Annex IV listed lake that is less vivid and the teal with an ultramarine and chromium green blend, retests both for morphing over eight weeks, and relabels. Separately, the review finds that one mica used for shimmer across four bars contains ferric ammonium ferrocyanide (CI 77510), which is fine for the soaps but would have blocked the lip balm the maker was planning, so a different mica is specified for that project in advance. The colour section of the file takes two weeks longer than the rest of the assessment and nothing else in the range changes.

Related reading

• Cosmetic colourants, mica and glitter: Annex IV rules
• CPSR for handmade soap
• CPSR cost for variants and shades
• The microplastics and glitter ban
• Turmeric and kaolin clay soap
• How to write a compliant cosmetic label
• All regulatory compliance articles

Myths we hear

• If it is sold as soap safe it is legal. Soap stable describes performance at high pH; Annex IV describes legality, and the two are unrelated.
• Mica is one ingredient. It is a coated mixture, and every coating pigment needs its own CI number and its own check.
• Food colouring must be fine on skin. Food and cosmetic positive lists differ, and many food colours are not Annex IV listed.
• Natural colourants need no documentation. Every ingredient is assessed by identity and specification, and several botanicals are irritants or photosensitisers.
• Tiny amounts do not need declaring. There is no minimum threshold for ingredient listing; colourants are declared however little is used.

What to do this week

1. List every colourant you use with its CI number, and flag any you cannot find one for.
2. Request specifications and batch certificates with heavy metal data for all of them.
3. Check each mica's component pigments against Annex IV, including the field of application.
4. Replace any colourant from a craft, resin or candle supplier with a specified cosmetic equivalent.
5. Ask your assessor whether a may contain list suits your range, or plan one ingredient list per shade.

Frequently asked questions

Official sources and legislation

• Regulation (EC) No 1223/2009 on cosmetic products
• The Cosmetic Products Enforcement Regulations 2013
• OPSS guidance: Regulation 1223/2009 and the Cosmetic Products Enforcement Regulations 2013 (GB)
• Annex IV to Regulation 1223/2009 (GB version, colourants)
• CosIng: Annex IV list of colourants (EU)
• Article 19 labelling (GB version)
• Regulation (EU) 2023/2055 restricting synthetic polymer microparticles
• Scientific Committee on Consumer Safety (SCCS)
• FDA: Color Additives Permitted for Use in Cosmetics