CPSR for Shaving Soap, Cream and Brushless Shave: Lather, Potassium and Broken Skin

Shaving is the one everyday grooming habit that deliberately takes skin off. The blade removes hair, a thin slice of the stratum corneum and, on a bad morning, a little more. That is why a lather that feels fine on the back of your hand can burn on a freshly shaved neck, and why a Cosmetic Product Safety Report for a shaving soap reads differently from one for a body wash, even when the ingredient lists look alike.

The law does not change. In the EU and Northern Ireland the framework is Regulation (EC) No 1223/2009. In Great Britain it is the assimilated version of the same Regulation, amended by Schedule 34 of SI 2019/696 and enforced through the Cosmetic Products Enforcement Regulations 2013. What changes is the exposure scenario the assessor writes down, and almost everything else in the report follows from it.

This guide covers the whole shaving shelf: hard pucks and soft croaps, tub creams, tube lathering creams, brushless creams, shave oils and aerosol foams and gels. If you make the aftershave that goes with them, our aftershave balm guide picks up where this one stops.

Why the razor changes the exposure scenario

The assessor builds the scenario from real use. For a shaving product that means lather worked onto a wet face or legs, left for one to three minutes, scraped through by a razor two or three times, then rinsed. The product is touching skin whose barrier is being reduced during the contact time, with micro-abrasions that are open when the next pass of lather arrives.

Three things follow. Local effects matter more than the systemic margin of safety, because the amount absorbed is still small but irritation is amplified. Microbial quality matters more, because contaminated product on broken skin is a bigger risk than on an intact arm. And stinging ingredients that people enjoy in a foot balm need a reason to be there, because a customer who feels a sting assumes damage.

The SCCS Notes of Guidance (12th revision) give shaving cream an exposed skin area of 305 cm² once a day, but no default daily amount in their exposure tables. So the assessor has to justify one, usually from your pack size, how long a tub lasts and the standard 0.01 retention factor for rinse-off products. Give them real usage data if you have it. It makes the numbers more honest than a borrowed figure.

Dual lye soaps and what the assessor needs

Most traditional shaving soaps are saponified with both potassium hydroxide and sodium hydroxide. Modern artisan soaps and soft croaps usually lean heavily towards potassium, often 70 to 90 percent of the lye, while harder pucks carry more sodium. The reason is lather. Potassium soaps dissolve easily and build a slick, abundant lather quickly. Sodium soaps add hardness and the dense structure that holds up through three passes without collapsing.

For the file, your assessor will want:

• the full oil and fatty acid blend with percentages,
• the weight of each hydroxide and its stated purity (KOH flake is often sold at around 90 percent, which changes the maths),
• the superfat and water content,
• the measured pH of the cured soap, ideally from three batches,
• evidence that free alkali is controlled, such as a free alkali titration or a consistent phenolphthalein drop test.

Two lyes means two saponification values for every oil, so mistakes are easier to make. We check the calculation rather than assume it. One wrong purity figure for KOH can leave a soap lye-heavy.

Potassium hydroxide, free alkali and pH

Potassium and sodium hydroxide sit in Annex III, entry 15a of the Regulation (the GB Annex III carries the same entry). The listed uses are nail cuticle solvents, hair straighteners, depilatories and, for other uses as a pH adjuster, a finished-product pH below 11. In soap the hydroxide is not a pH adjuster. It is a reactant that is used up in saponification, so the safety question is how much unreacted alkali is left in the bar or cream.

A well made shaving soap typically measures roughly pH 9 to 10.5. That is normal for true soap and is not a safety problem on its own. Assessors commonly use the pH 11 figure from entry 15a as a sense check. A reading above it, or a positive free alkali test, sends the batch back for investigation before anything else in the report is signed. Our guide to pH in cosmetics explains how to measure a soap properly, as a dilution rather than by pressing a strip onto a wet puck.

On the label, a saponified product can be declared by its reaction products (Potassium Stearate, Sodium Cocoate and so on) or by the starting materials (Stearic Acid, Cocos Nucifera Oil, Potassium Hydroxide, Sodium Hydroxide). Pick one approach and use it consistently across the range.

Stearic acid, tallow and plant versions

Stearic acid is near the top of almost every shaving soap recipe, often a third or more of the fat charge. Stearates give the dense, almost whipped lather the category is judged on. Tallow does a similar job and has a loyal following. Plant versions usually combine stearic acid with shea, kokum or a hydrogenated vegetable oil to copy tallow's fatty acid profile.

None of these worry an assessor at the levels used in a rinse-off product. Where they do matter is paperwork. Tallow needs a specification that confirms what it is and how it was rendered. Plant stearic acid needs its origin confirmed, because a palm-derived stearic acid sold as "vegetable" becomes a claims problem for a brand that markets itself as palm free. Our guide to natural, vegan and palm free soap claims goes through the evidence you need.

Triethanolamine and the cream route

Many soft shaving creams are not saponified from oils at all. They are made by neutralising stearic acid in a creamy base, with potassium hydroxide or with triethanolamine. The result scoops out of a tub and lathers almost instantly.

Triethanolamine falls under Annex III, entry 62 (trialkylamines, trialkanolamines and their salts). There is no fixed maximum in rinse-off products and a 2.5 percent maximum in leave-on products. In both cases it must not be used with nitrosating systems, the raw material must be at least 99 percent pure with no more than 0.5 percent secondary amine, nitrosamine content must stay below 50 µg/kg, and it must be kept in nitrite-free containers. The real concern is nitrosamine formation, so the assessor will ask what else is in the formula and for supplier specifications that show nitrite and nitrosamine control.

A brushless cream that some users wipe off instead of rinsing is worth discussing with your assessor. If the directions allow the product to stay on the skin, the leave-on limit may be the safer basis. If you would rather avoid the question entirely, potassium hydroxide neutralisation gives a similar texture and a simpler assessment.

What actually gives glide and cushion

Ingredient or factor	What it does	What the assessor looks at
Soap content and lather density	The main driver. A thin lather gives the blade nothing to ride on.	Free alkali and pH, as above
Glycerin, sorbitol, propanediol	Hold water in the lather so it does not dry out mid-shave	Unremarkable at normal levels
Bentonite or kaolin clay	Add slip and a cushioned feel	Heavy metal specification from the supplier
Lanolin	Slickness and a soft after-feel	A known contact allergen for some users; consider it in the sensitive-skin claim
Silk, oat and protein hydrolysates	Some slip and after-feel	Supplier specification; wheat protein grade if hydrolysed wheat is used
Superfat	Improves feel but can reduce lather stability	A very low superfat can leave the skin stripped
Chelating agent	Protects lather in hard water and supports preservation	Within normal use levels

Menthol, camphor and the cooling problem

Menthol, camphor, peppermint and eucalyptus oils give the cooling hit a large part of this market wants. They are also the ingredients most often reduced during assessment. They irritate at the levels that produce a strong effect, and they are applied to skin that is about to be scraped. A level that feels pleasant on an intact chest can be painful on a shaved neck.

There is now a labelling angle too. Regulation (EU) 2023/1545 added menthol, camphor, peppermint oil and eucalyptus globulus oil to the list of fragrance allergens in Annex III. In the EU and Northern Ireland they must be named in the ingredient list above 0.01 percent in a rinse-off product and 0.001 percent in a leave-on one. Products placed on the market from 31 July 2026 must comply, and older stock can be sold until 31 July 2028. Great Britain has not adopted the expanded list, so a GB label still follows the original list. A single label that carries the longer EU list is acceptable in GB, but check legibility before you print.

Camphor has no concentration limit in Annex III, but it is toxic if swallowed in quantity, so the assessor will justify the level from its toxicology and expect a keep out of reach of children warning. The same goes for strongly mentholated or eucalyptus products left in a family bathroom.

Preservation by format

Format	Free water	Preservative	Challenge test
Hard puck	Low; bound in the soap	Usually not	Often justified as low risk under ISO 29621, with the reasons recorded
Soft croap	Higher, often with a lot of glycerin	Case by case	Depends on water activity and pH; ask the assessor
Soft shaving cream in a tub	Yes	Yes	Yes, and consider an in-use study
Lathering cream in a tube	Yes	Yes	Yes
Brushless shave cream	Yes	Yes	Yes
Shave oil	None (anhydrous)	No	Not normally
Aerosol foam or gel	Yes	Usually	Yes; the sealed can reduces in-use risk

Water decides. ISO 29621 lists factors that make a product hostile to microbes, including pH of 10 or above and water activity of 0.75 or below. A puck at pH 9.6 does not pass on pH alone, so the argument usually rests on low free water and manufacturing records. Write it down. An assessor cannot sign "low risk" without the reasons.

Tub creams deserve the most care. A wet brush goes into the tub at every use, carrying water, skin flora and whatever is on the bathroom shelf. A standard challenge test on the formula alone understates that. Pick a preservative that works at the real pH of the cream, which for a stearate base is often above the range where organic acid systems such as sodium benzoate or potassium sorbate are effective. Set the period after opening with the brush in mind, not copied from a body lotion.

Aerosol foams and gels

An aerosol shave foam is a cosmetic in a pressurised can, and the can brings its own law. In the EU that is the Aerosol Dispensers Directive 75/324/EEC, which covers container design and testing, filling limits, the reversed epsilon mark and warnings about pressure, heat, sunlight, puncturing and burning. Flammable propellants add flammability categories aligned with CLP. In Great Britain the Aerosol Dispensers Regulations 2009 apply, and the can must carry the UK marking or the reversed epsilon.

Few small brands fill their own aerosols, so the filler holds most of this expertise. The Responsible Person is still answerable for the finished product, though, so the PIF needs the filler's documents: container specification, pressure test evidence, propellant identity and amount, and the artwork showing the aerosol markings. Ask for that pack before you finalise the formula, not after the first run.

Fragrance on skin that has just been shaved

IFRA places shaving creams of all types, including sticks, gels and foams, in Category 9, the rinse-off group that also holds bar soap and shower gel. That part is straightforward. The trap is the rest of the range. A pre-shave oil is left on the skin, and an aftershave splash or balm is applied straight after the razor. Those need a leave-on category with much lower limits, usually Category 4 for an alcoholic splash or 5B for a face balm. Read our guide to IFRA certificates before you reuse one certificate across a whole scent family.

Allergen declaration follows the rinse-off threshold for soaps and lathers, and the leave-on threshold for anything that stays on. If you want an unscented product for sensitive skin, describe it as fragrance free only if it contains no fragrance at all, including masking agents.

Claims about closeness and razor burn

Every claim must meet the six common criteria in Regulation (EU) No 655/2013, and some shaving claims drift towards medicine or biocide territory.

• "Rich, stable lather." A performance claim about the product. Fine with test evidence.
• "Protects skin while you shave." Supportable in general terms where the lather provides a lubricating layer.
• "Prevents razor burn." Moves towards preventing a skin condition. Soften to "helps reduce irritation during shaving" and hold evidence.
• "Treats ingrown hairs." A treatment claim. Not a cosmetic claim.
• "Antibacterial" or "antiseptic." Borderline. Unless cleansing stays the main purpose and the claim is substantiated, it can pull the product under biocides or medicines law. See the Commission's borderline products guidance.
• "Stops bleeding." A medicinal claim. Alum blocks and styptic pencils need specific advice.
• "Suitable for sensitive skin" and "dermatologist tested." Acceptable with a proper study under dermatological supervision. The second describes who ran the test, not the result.

A worked example: the winter edition that stung

A small brand launches a dual lye shaving soap and a matching pre-shave oil in a strong mentholated winter scent. Returns start in week three. Nearly every complaint mentions burning on the neck, not the cheeks.

The review finds three problems. The menthol level in the soap was set by feel on the back of a hand and is roughly twice what the assessment would support for a product used under a razor. The pre-shave oil used the fragrance supplier's Category 9 figure, which suits the soap but not an oil that stays on the skin. And the soap's superfat is one percent, which gives a squeaky finish and leaves very little behind to protect the neck.

The fix: menthol cut by more than half, the oil reformulated to its leave-on IFRA category, superfat raised to about five percent, and a warning added not to use on cut or irritated skin. Customers say the new version shaves better, because the cooling is still there and the sting is gone. Because the edition is also sold in France, menthol and peppermint oil now appear by name in the EU ingredient list. The brand then reruns its whole range against the correct IFRA categories and finds two more certificates that do not match the product.

What to send your assessor

• Full formula for each product, with INCI names and percentages, and the format (puck, croap, tub, tube, brushless, oil, aerosol).
• Lye figures, purity, superfat, water content, cured pH and free alkali results for any soap.
• Supplier specifications and SDSs for every raw material, including triethanolamine nitrosamine data where used.
• IFRA certificates and allergen breakdowns for each fragrance, in the right category for each product.
• Menthol, camphor and essential oil content stated separately.
• Stability data and, for water-containing formats, challenge test results.
• Draft label and claims, plus the filler's documentation pack for any aerosol.

Our CPSR document checklist has the full list, and the handmade soap CPSR guide covers the cold process basics if you also make bath soap.

Related reading

• CPSR for handmade soap
• CPSR for aftershave balm
• CPSR for beard oil and beard balm
• pH in cosmetics: why the safety assessor asks
• Restricted cosmetic ingredients: Annex III explained
• Fragrance allergen labelling: the 2026 and 2028 deadlines
• IFRA standards and certificates explained
• The cosmetic challenge test explained
• How to prepare for a CPSR: the document checklist
• All regulatory compliance articles

Myths we hear

• A shaving soap is just a soap with a different label. The chemistry may look similar, but the use is not. A razor passes over the lather several times, so the assessor judges irritation for abraded skin and may set a lower fragrance or menthol level than the same base would get as a hand soap.
• More menthol means a better shave. Past a modest level menthol stings on freshly shaved skin, and customers read sting as damage. In the EU it is also now a declarable allergen above 0.01% in a rinse-off product.
• A hard puck can never go wrong. It rarely needs a preservative, but free alkali, rancid oils, fragrance limits and allergen labelling all still apply. Low microbial risk has to be argued in the file, not assumed.
• Triethanolamine is banned in Europe. It is restricted, not banned. Annex III entry 62 allows it in rinse-off products without a fixed ceiling and at up to 2.5% in leave-on products, provided it is pure, low in secondary amine and kept away from nitrosating agents.
• My aerosol filler takes care of the compliance. The filler holds the pressure testing and container data, but the Responsible Person is answerable for the finished product. That data has to sit in your Product Information File.

What to do this week

1. Tell your assessor in writing that each product is a shaving product and say how it is used: brush or hand, wet face or dry, rinsed or wiped off.
2. Recalculate your dual lye recipe with both saponification values and the real purity of each hydroxide, then confirm free alkali and pH on three batches.
3. Check every fragrance certificate for the right IFRA category: 9 for the soap or cream, a leave-on category for any pre-shave oil or aftershave in the same scent.
4. List the menthol, camphor and mint or eucalyptus oil content of each product and add them to your allergen calculation for EU and NI labels.
5. For tub creams loaded with a wet brush, book a challenge test and ask the lab about a simulated in-use contamination study.
6. If you sell an aerosol foam or gel, ask the filler for its container specification, pressure test records and draft markings before you lock the formula.

Frequently asked questions

Official sources and legislation

• Regulation (EC) No 1223/2009 on cosmetic products (EUR-Lex)
• Regulation 1223/2009, consolidated text incl. Annex III (EUR-Lex, 1 May 2026)
• GB Cosmetics Regulation (assimilated Regulation 1223/2009, legislation.gov.uk)
• GB Annex III, restricted substances (legislation.gov.uk)
• SI 2019/696, Schedule 34: cosmetic products (GB amendments)
• The Cosmetic Products Enforcement Regulations 2013 (SI 2013/1478)
• OPSS guidance: Regulation 1223/2009 and the Cosmetic Products Enforcement Regulations 2013 (GB)
• Commission Implementing Decision 2013/674/EU: guidelines on Annex I (safety report)
• SCCS Notes of Guidance, 12th revision (SCCS/1647/22)
• Regulation (EU) 2023/1545: fragrance allergen labelling
• Regulation (EU) No 655/2013: common criteria for cosmetic claims
• European Commission: borderline cosmetic products
• Aerosol Dispensers Directive 75/324/EEC (EUR-Lex)
• The Aerosol Dispensers Regulations 2009 (SI 2009/2824, GB)
• IFRA Standards documentation (51st Amendment guidance)
• ISO 29621:2017 microbiologically low-risk cosmetic products