Challenge Testing for a Home Based Business

RenKBRenKB Member, PCF student

I was wondering how much of the product testing process could be reasonably handled on site for a home-based business? Could anyone also share which equipment they would recommend purchasing to manage that? Thank you, and any input is much appreciated.


  • Some things to consider:

    1 At least rent a small office or warehouse. Unless you only plan to service customers by Email/mail, they won't trust a business located in a garage.

    2 You'd need at least a makeshift cleanroom
    and/or glovebox
    to work with bacteria.
    You'd need a way to dispose of bacteria before disposal, by either degrading them with chemicals
    On the cheap you can probably use concentrated Sodium hydroxide (be careful) to kill bacteria, then neutralizing it with acid.
    or flaming/incineration
    You just can't flush live bacteria down the drain.

    3 As anything bacterial sounds scary, neighbors might complain to the regulators.
    Another reason to rent a small office or warehouse IMO.

    4 For some reports, you may need a licensed microbiologist to sign them.
    But you can offer yours as 'preliminary testing', 'as-is', 'not guarenteed', or something like that.

    5 You need to make sure you get quality bacteria, and they can reproduce. Cultivation on agar plates, and watching under microscope is required in every bacteria batch.

    Other than that you can give it a try, if you have the time. It doesn't seem to require investing a huge amount of money  ... unless your local regulations are really stringent.
  • RenKBRenKB Member, PCF student
    Thank you, Gunther. That is very helpful. I agree that a rented space would be best. What if I just wanted to do stability testing? Are there any particular incubators you would recommend?
  • When you say "home-based business," in which country are located?

    A lot will depend on the local cosmetics regulations. In Malaysia, where we are, nothing less than an audited GMP facility will be accepted. The other alternative is to produce illegally, which many do, but it does limit where you can sell.
    Dr. Mike Thair
    Cofounder & Chief Formulator
    Indochine Natural
  • RenKBRenKB Member, PCF student
    Definitely not interested in anything illegal. Located in USA! 
  • Bill_TogeBill_Toge Member, Professional Chemist
    if you're not intending to run a full microbiology lab I'd suggest outsourcing it to a third party; it will need an awful lot of investment in the site, equipment and specially qualified/trained staff
    UK based formulation chemist. Strongest subjects: hair styling, hair bleaches, hair dyes (oxidative and non-oxidative) I know some stuff about: EU regulations, emulsions (O/W and W/O), toothpaste, mouthwash, shampoos, other toiletries
  • MicroformulationMicroformulation Member, Professional Chemist
    The absolute maximum I would recommend anyone doing is perhaps using the Microcult slides as a tool WITH outside testing. Unless you are a microbiologist, you really should outsource this testing. If the testing is too expensive, this speaks to an issue with your Business model and funding, not a Technical issue. Microformulation Cosmetic Consulting provides Custom Formulations for both large Commercial accounts as well as smaller entrepreneurs. We can provide Naturally compliant Formulations under the NSF, NPA, Whole Foods and USDA Organic Certifications. BS.Pharm Albany College of Pharmacy, Union University.
  • SibechSibech Member, Professional Chemist
    A quick caveat, I am not based in the US and can't guarantee my suggestion necessarily comply with those regulations.

    Personally, I would definitely outsource the actual microbial challenge testing. For new developments in a small company, I would find a microbial testing kit to use during development and then get the challenge test of a seemingly microbially stable formulation completed elsewhere.
    If you use an external safety assessor they are also more likely to immediately accept an approved report from an accredited lab than in-house testing (where the methodology will be looked more into).

    Also, when doing challenge testing on a new product consider sending multiple samples with different preservation systems - you'll save yourself a lot of waiting time this way if some are rejected.

    What if I just wanted to do stability testing?
    As for general stability testing, in general, you should get equipment for measuring your stability endpoints (these vary depending on the product but can include a viscometer, refractometer, colourimeter (particularly for colour cosmetics), microscope and ). A centrifuge for a quick and dirty stability test and an oven + freezer for accelerated and freeze-thaw stress tests.

    Dabbling Formulator — Qualified Cosmetic Safety Assessor — experienced in claim substantiation & EU regulatory affairs.
  • My advice is to buy an incubator that doesn't reset itself during brief power outages.
    Especially useful when samples are left overnight, so nobody's able to quickly reset it.

    Even old-school dial-type models are preferable to modern electronic ones IMO.
    Either that, or an UPS + battery cabinet.
  • MarkBroussardMarkBroussard Member, Professional Chemist
    I'm a degreed Microbiologist and formulator and I would not conceive of ever trying to do my own in-house challenge testing.  This is from both a business/product liability and practical perspective.  It simply is not practical and I suspect way beyond your technical capabilities to set up for in-house challenge testing (no offense intended)

    As Mark noted above, send your products out to a professional laboratory for Preservative Challenge Testing (reduces your liability) and when you're making production batches, use microbial test strips as an internal check, coupled with plate count tests performed by a third party lab.

    Product Stability Testing:  Simply buy an inexpensive oven for elevated temperature and use your home freezer for freeze/thaw testing. 
    Chemist/Microbiologist formulating in the Organic & Naturals & Clean Beauty arena under ECOCert/Natural Products Assn/Whole Foods/National Organic Program/Clean At Sephora/Credo Clean guidelines focused skincare & haircare products. 

    See website for details
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