Stability and Safety Testing Before Launch: Third-Party Made Products
Before a third-party made cosmetic launches, it needs stability testing, packaging compatibility checks, preservative challenge and microbiological testing, a safety assessment and evidence for any claims. Ready formulas often carry some data already; custom formulas and claim studies are usually commissioned by the brand. Write who does what into the brief and contract.
A product made by a third party is not ready to launch until it has passed stability, packaging compatibility, preservation and safety checks, and you should know before you place a bulk order which of these the manufacturer runs and which you must commission yourself. Most launch problems that show up as separation, colour change, odour, leaking packs or customer irritation complaints were visible in a test that was skipped or rushed.
This guide covers each test in plain terms, who normally commissions and pays for it, what to write into your brief, and where the manufacturer's responsibility ends and yours begins. It sits inside the wider journey described in the complete guide to third-party cosmetic manufacturing in India.
Why testing sits before bulk, not after
A sample that looks good on the day it is filled tells you very little about the product in month six. Emulsions can split, fragrance can shift, colour can fade, a pump can seize, and a preservative system can weaken once a formula meets a particular plastic. These things take time to appear, which is why stability work runs alongside development and sample approval rather than after production.
Ordering bulk before the evidence is in means that any fault is discovered after you own thousands of filled units and printed cartons. Ordering after means a fault costs you a reformulation and a delay. The second is cheaper every time.
The tests, one by one
Stability testing
Stability testing asks whether the product keeps its appearance, colour, odour, texture, pH and performance over its intended shelf life. It usually has two tracks.
- Accelerated stability. Samples are held at raised temperatures, often alongside cold storage and light exposure, to push ageing faster and flag weak formulas early.
- Real-time stability. Samples are held at normal storage conditions and checked at planned intervals for the full claimed shelf life. Typical programmes run for months, and the real-time track often continues after launch.
Temperature cycling (alternating warm and cold periods) is a common addition for creams, lotions and anything that may travel through hot and cold climates. Ask what the pass criteria are before the test starts, for example no visible separation, no change in colour or smell beyond an agreed tolerance, and pH within an agreed range.
Packaging compatibility
The formula must be tested in the pack you will actually sell it in, not only in a glass jar in the lab. Plastics can absorb fragrance or oils, pumps can clog with thick or particulate formulas, and some actives stain or soften certain materials. If you change the bottle, closure or liner after approval, treat it as a change that needs fresh checks. The packaging guide explains who sources which components and why that matters here.
Preservative efficacy (challenge) testing
Any water-containing product needs a preservation system, and a challenge test checks that it works. The lab deliberately introduces a controlled set of microorganisms into the product and measures how well it reduces them over a set period. This protects your customer and your brand from products that grow mould or bacteria once the consumer starts dipping fingers into a jar.
Run the challenge test on the final formula in its final pack type where possible, because open-mouth jars and sealed pumps put very different stress on a preservative system.
Microbiological checks
This is separate from the challenge test. It counts and screens for unwanted organisms in the finished product, and it is usually repeated as part of batch release. Ask whether the first pilot batch and the first production batch are both checked, and ask to see the results rather than a one-line statement.
Safety assessment and patch testing
A safety assessment reviews every ingredient at its concentration in your formula, considers how the product will be used, and concludes whether it is suitable for the intended market. Many brands also ask for a patch-style tolerance study on volunteers for products meant for sensitive areas or sensitive-skin positioning. Requirements vary by product type and by the country you sell in, so check current rules with your regulatory adviser before you decide what to commission.
Claim substantiation
Stability and safety are about the product. Claim substantiation is about what you say on the label and in adverts. If your pack says long-lasting, hydrating or non-sticky, you need evidence that matches the exact wording. A manufacturer's ready formula comes with its own ingredient story, but proof for your marketing claim is generally your responsibility unless the contract says otherwise. Keep claims modest until the evidence exists.
Who commissions and who pays
This varies by manufacturer and by whether you are buying a ready formula or a custom one. Use the list below as a starting checklist for the conversation, not as a fixed rule.
- Ready formula (private label). The manufacturer often already holds stability and preservation data on the base formula. Ask for it. You may still need to confirm it in your chosen pack, and any fragrance, colour or ingredient change you request can invalidate older data.
- Custom formula. The manufacturer's R&D team usually runs development-stage stability and preservation checks, and the cost may be inside a development fee or quoted separately. Get this stated line by line on the quote.
- Third-party lab studies. Independent patch studies, extended real-time studies and claim-specific trials are normally commissioned and paid for by the brand, because they support your claims and your market.
- Packaging tests. Whoever supplies the packaging should be able to supply specification data, but the compatibility result belongs to the filled combination, so agree who runs it.
Write the answer to each line into your manufacturing agreement. Silence in a contract is how a brand ends up discovering, after launch, that nobody was responsible for the challenge test.
What to put in your brief
The earlier your intended conditions are on paper, the more useful the testing is. Include these in the brief and sample request:
- The target shelf life you want to print on the pack, and the storage conditions you expect customers to have.
- The markets you will sell in, since climate and rules differ.
- The exact pack: bottle, jar, pump, tube, liner, closure and any decoration.
- Any claims you plan to make, in your actual draft wording.
- How the product is used (rinse-off, leave-on, on the face, around the eyes, on children), which affects safety review.
- Which test reports you expect to receive and in what form.
Reading the results
A test report is useful only if you can tell what it covered. Check these points whenever a report arrives:
- Does the batch number or formula code match the sample you approved?
- Was the product tested in the same pack you are buying?
- Are the test conditions and intervals stated, and the pass criteria defined in advance?
- Is the testing lab named, and is the report signed and dated?
- Do results cover the shelf life you plan to claim, or only part of it?
If the answer to any of these is no, ask the manufacturer to close the gap before you approve the bulk order. Be wary of a supplier who offers a certificate in place of data. The quality system guide covers what certificates do and do not prove.
When a change restarts the clock
Approved does not mean permanent. A new fragrance, a different supplier for a raw material, a changed pump or a different batch size can each justify a re-check. Agree up front which changes need your written sign-off and which need fresh testing. The tech transfer guide applies the same logic when a product moves between factories.
A short note on Harrods Health
Harrods Health runs an in-house R&D lab and works with both ready formulas and custom development, and you can read how testing and quality fit into its process on the testing and quality page. Whichever manufacturer you use, ask for the evidence in writing and match it against the checklist above.
If you want to discuss a specific product, pack and target market, you can start with the contact page.
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