When I started looking for an OEM partner for our mouthwash line, I assumed the hard part would be finding manufacturers willing to work with a brand at our volume. It turned out finding candidates was easy. The hard part was figuring out which ones were actually capable of delivering what they were describing in their introductory emails.
I spent about two months doing proper due diligence on three shortlisted manufacturers before making a final decision. Looking back, the process taught me as much about what to look for as it did about any specific supplier.
How I Built the Shortlist
I started with trade platform searches and referrals from people I knew who’d done private label in the personal care space. The referrals were more useful. A name from someone who’d actually placed orders and received product tells you something that a listing with good photos doesn’t.
I ended up with three manufacturers I thought were worth a serious evaluation:
The first was a large facility with broad capability across cosmetics and personal care, clear ISO certifications, and a well-organized English-language website. They clearly had experience with international clients.
The second was smaller, more specialized in oral care specifically, and came recommended by someone who’d sourced toothpaste from them. The contact was responsive and specific in their initial answers.
The third was mid-sized, quoted the most competitive pricing, and had an impressive list of claimed certifications — though I hadn’t yet verified any of them.
Round One: Asking the Same Questions to All Three
I sent each manufacturer the same set of questions and paid close attention to both the answers and how they were delivered.
I asked about their formulation process for alcohol-free mouthwash, their preservative system, how they handle stability testing, their MOQ for a custom formula, and what their lead time looked like from formula approval to first shipment. I also asked for references from existing clients in markets similar to mine.
The first manufacturer answered thoroughly and specifically. They described their preservative challenge protocol, told me their accelerated stability testing ran to 12 months, and gave me two client references without hesitation.
The second was equally specific on formulation questions — more so, actually, since oral care was their focus. They pushed back on one of my assumptions about formula compatibility in a way that was clearly informed by real experience rather than a desire to close a deal.
The third gave me broad, reassuring answers that didn’t actually address what I’d asked. When I followed up with more specific questions, the responses got vaguer. The pricing was attractive but the information gap was getting harder to ignore.
Sample Evaluation
I requested samples from all three and specified exactly what I wanted to evaluate: a standard alcohol-free spearmint formula at the volume we were planning to launch with, in the packaging type we’d tentatively chosen.
The first two delivered samples within the timeframe they’d quoted. The third was two weeks late and sent a sample in different packaging than I’d specified, with an explanation that was hard to follow.
On the samples themselves: the first was technically competent but the flavor profile was generic — it would have done the job but wouldn’t have stood out. The second had a more interesting texture and the flavor balance was noticeably better. Both cleared my basic evaluation criteria for foam, rinse feel, and aftertaste.
The third’s sample, when it finally arrived, had a slightly off-smell that neither of the others had. I didn’t take it further.
Verifying the Credentials
This step is easy to skip and worth not skipping.
Both remaining manufacturers had provided certification documents. I checked that the certificates were current (they were), that the facility address on the certificate matched what I’d been given (it did for both), and I looked up the certifying body to confirm it was legitimate rather than a self-issued document dressed to look official.
I also asked each manufacturer whether they could produce under OTC drug GMP standards, since we were considering a fluoride variant down the line. The first could; it was a different production line with separate documentation. The second didn’t have that capability but was transparent about it and suggested a pathway if we needed it in the future.
The Decision
On technical capability, both remaining manufacturers were qualified. The decision came down to communication quality, formulation depth, and a gut sense of how problems would be handled.
The second manufacturer — the specialist — had been more candid throughout the process. They’d pushed back once, acknowledged a limitation, and given more specific answers consistently. That pattern is what I’ve come to associate with suppliers who will tell you something has gone wrong before it becomes a crisis, rather than after.
We went with Cinoll for our mouthwash line. The formulation depth in oral care specifically, the quality of answers throughout the evaluation, and the early evidence of honest communication made it the more defensible choice even at a slightly higher unit cost than the alternative.
What I’d Do Differently
One thing I’d change: I’d ask for references earlier. I asked at the beginning of the process, but I didn’t actually call the references until I was close to a final decision. Two of the four references I contacted gave me genuinely useful information — one mentioned a delivery delay that had since been resolved, which was worth knowing. I should have made those calls in parallel with the sample evaluation rather than after it.
I’d also ask more specifically about what happens when a batch fails QC. Not as a gotcha question, but because the answer reveals a lot about how the manufacturer operates under pressure. Both of the manufacturers I took seriously had clear answers. A supplier who hasn’t thought about their rejection and reprocessing protocol is one who hasn’t had enough production volume to encounter the problem — which is its own data point.
The evaluation process is slow and it costs money in samples and time. But the cost of getting it wrong — a production run that doesn’t meet spec, a supplier who disappears when something goes sideways — is significantly higher. The two months I spent evaluating were not the most exciting part of the project. They were probably the most valuable.
