How to commission cosmetic stability testing
Agree the test plan with your safety assessor before booking a laboratory. Use the final formula and production packaging, identify the sampled batch, and commission stability, microbial quality and preservative efficacy work as appropriate. Send complete reports and supporting records for assessment. Factory coordination can be handled by Cambridge China Bridge.
Start with the assessor’s testing brief
For Great Britain, a cosmetic’s safety must be checked by a qualified safety assessor before it is made available to consumers. Bring the assessor into the project before buying a laboratory package. Ask them to identify the evidence gaps for your formula, intended users, application area, storage and use after opening.
Agree a written plan covering stability, microbiological quality, preservative efficacy and packaging compatibility. Ask the assessor and laboratory to explain any omitted work and record the justification. This guide concerns commissioning the tests; use our cosmetic safety assessment guide for the wider file.
Freeze the formula and identify the samples
Give the assessor the complete formula with ingredient identities, concentrations, functions and raw-material specifications. Identify compound ingredients and their supplied composition rather than sending only the consumer ingredient list. Arrange confidential disclosure directly to the assessor where necessary. Record the formula revision, manufacturing process, batch identity and filling date.
Prefer samples made using the intended production process and filled into the intended sale packaging. Tell the laboratory whether they are development samples or production samples. Ask the assessor to confirm whether they represent the product you will sell. Keep matching retained samples and link dispatch records to laboratory receipt using our sample chain-of-custody guide.
Include the actual production packaging
Specify every material touching the formula, including the container, lining, seal, closure and dispensing components. Supply material specifications, supplier references and assembled packs. Discuss how the product will be transported, stored, opened and dispensed. A formula tested in a laboratory vessel does not establish how it behaves in your chosen retail pack.
Ask for observations on separation, colour, odour, viscosity, acidity, leakage, evaporation and dispensing performance where relevant. Agree how to investigate interaction between the formula and packaging, including possible migration where the assessor identifies a concern. Use our formula and packaging compatibility guide for the separate pack trials.
Commission distinct tests with clear outputs
Separate microbial quality testing, which examines contamination in the submitted sample, from preservative efficacy testing, which challenges the product’s protection against introduced microorganisms. A satisfactory contamination result alone does not establish preservative performance during use. Ask the assessor whether challenge testing is appropriate and what evidence supports any proposed omission.
For each study, agree the method and version, sample quantity, storage conditions, duration, observation schedule, acceptance criteria and reporting format. Ask how the microbiological method accounts for the formula suppressing microbial recovery. Request stability observations and results over time, rather than a pass certificate alone. Check the laboratory’s relevant capability through our laboratory accreditation guide.
Deliver evidence and control later changes
Send the assessor the signed laboratory reports, agreed protocols, sample identities, formula revision, packaging specifications, batch records and any deviations or failed results. Ask for the reasoning supporting shelf life, storage advice and use after opening. The safety assessment should take the form of a cosmetic product safety report signed by a qualified safety assessor.
If results fail or remain inconclusive, agree investigation and corrective work before treating the study as complete. Refer later changes to fragrance, preservative, ingredients, manufacturing or packaging back to the assessor for a decision on further evidence. Cambridge China Bridge’s staff in China can coordinate factory records and sample dispatch against the agreed brief.
Frequently asked questions
Can I use the factory’s existing cosmetic test report?
Send it to your assessor with the tested formula, batch and packaging details. Ask whether it represents your product and whether its methods and results answer the agreed brief.
Does a microbial pass replace a challenge test?
A microbial quality result concerns contamination in the sample. A challenge test examines preservative performance against introduced microorganisms. Ask your assessor which evidence your product needs.
How long should cosmetic stability testing take?
Ask the laboratory and assessor to agree the duration, conditions and observation schedule for your formula and proposed shelf life. Ask what interim results can support and what remains unresolved.
Do I need more testing after changing the packaging?
Give the assessor the changed materials, closure and dispensing details. Ask whether existing evidence remains relevant and what compatibility, stability or microbiological work should be repeated.