Personal Care & Home Care · Choose a Material / Solution
Preservative system selector
Four answers narrow the field: what the product is, the pH of its water phase, how it is packed, and any claim you have to respect. The tool returns relevant systems with their published pH behaviour and their partner requirements. It returns no dose, and it never says a formula is preserved.
This selector narrows options. It does not preserve a formula, it does not predict a challenge-test result, and it does not state that any substance is permitted for your product in Canada.
1 · What is the product?
Where water sits in the formula changes the question before any preservative is named.
2 · What is the pH of the water phase?
Measured on the finished product where possible. Bands, not point values — the arithmetic below uses each band's representative pH.
3 · How is it packed? (optional)
Packaging decides how the consumer contaminates the product in use.
4 · Any claim constraint? (optional)
A constraint removes options. It never makes a remaining option effective.
Answer the product type and the pH band. Nothing is shown until both are chosen, because a single answer never selects a preservative system.
Use this when
- You know your target pH and want to see which systems are still in their window.
- A claim constraint has removed your usual system and you need the remaining structure.
- You are packing into an open jar and want to see how that changes the requirement.
- You want a written shortlist to take into a challenge-testing plan.
How the output is produced
- Nothing is shown until product type and pH are chosen — one input never selects a preservative.
- Weak-acid systems are ranked by the published pKa against your pH: at pKa the acid is half undissociated, and the undissociated fraction falls tenfold for each pH unit above it.
- Systems that are not weak acids are shown as pH-independent for this purpose and are not ranked by pKa.
- Packaging and claim answers filter and annotate the list; they never add a dose.
- Every result carries the same closing requirement: challenge test the finished product in its final pack.
What this page does not determine
- The selector does not tell you a preservative will work, and it does not predict a challenge-test result.
- It returns no use level for your formula. Typical published ranges are shown as context, marked as such, and are not a recommendation.
- It does not establish permitted use. That is a Cosmetic Ingredient Hotlist question for your specific substance and product type in Canada.
- It does not assess compatibility with your actives, fragrance, surfactant system or pack material.
- It makes no safety, irritation or therapeutic claim about any listed material.
Relevant Allzone products
These are catalogue identities relevant to this decision. A listing here is not a statement that the material is suitable for your formula, and it is not a permitted-use, safety or performance claim.
- PhenoxyethanolGlycol ether preservative that is not governed by a weak-acid pKa window.
- Benzyl AlcoholAromatic alcohol used as a preservative and as a solvent for other systems.
- Dehydroacetic AcidWeak acid (published pKa ≈ 5.27) supplied as the acid or the sodium salt.
- Potassium SorbateSalt of sorbic acid (published pKa ≈ 4.76); activity depends on formulation pH.
- Sodium BenzoateSalt of benzoic acid (published pKa ≈ 4.20); activity depends on formulation pH.
- EthylhexylglycerinMultifunctional wetting agent used alongside a preservative, not instead of one.
- Disodium EDTAChelant that sequesters metal ions carried in by water and raw materials.
- Citric Acid (Anhydrous & Monohydrate)Acidulant used to bring an aqueous phase down into a weak-acid window.
- Lactic AcidLiquid acidulant used for pH adjustment where a solution dose point exists.
- Sodium CitrateBuffer salt used to hold a target pH after adjustment.
Where this comes from, and what it cannot tell you
Published physical-chemistry constants (acid dissociation)
Supports: Sorbic acid pKa ≈ 4.76, benzoic acid pKa ≈ 4.20, dehydroacetic acid pKa ≈ 5.27. The undissociated fraction of a weak acid falls as pH rises above its pKa.
Limitation: The undissociated fraction explains why a system weakens with pH. It does not quantify antimicrobial performance in a real emulsion.
Universal · Physical constants; stable.
ISO 11930 — Cosmetics, evaluation of the antimicrobial protection of a cosmetic product
Supports: That preservation is established by challenge testing the finished product in its final packaging, not by the identity of a preservative on an ingredient list.
Limitation: A test result applies to the exact formula, batch, pH and pack that was tested. Nothing on this page predicts a pass.
International · Standard method; confirm the revision your laboratory runs.
Health Canada — Cosmetic Ingredient Hotlist
Supports: That restricted and prohibited substances in cosmetics sold in Canada are defined by the Hotlist, and that the Hotlist entry — not this page — is the authority for any concentration limit or labelling condition.
Limitation: The Hotlist states restrictions. It never states that an unrestricted ingredient is effective, safe in your formula, or approved for your product.
Canada · Consult the current published Hotlist before every formulation decision.
Related knowledge & tools
- Cosmetic Preservative Selection GuideThe reasoning behind the shortlist: water, pH window and packaging exposure.
- Surfactant Thickening and the Salt CurveWhy an electrolyte or pH change moves viscosity in a surfactant system.
- Personal Care & Home Care productsThe catalogue identities referenced by the selector.
- Personal Care & Home Care KnowledgeChoose and compare, learn, calculate.