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COA, SDS and spec sheets: the documents to ask for before you pay a deposit
Five documents, what each one proves, who owes it to you, and which of them you will be asked for later by a retailer, an insurer or a marketplace.
Documents feel like the boring end of making a product, right up to the week a marketplace asks for one you do not have and your listing goes down. They are also the cheapest thing to get right, because the moment to ask is before you pay a deposit — when you still have leverage — and the cost of asking is one email.
The five
| Document | What it proves | Whose job | Asked for by |
|---|---|---|---|
| Specification sheet | What the product is meant to be | Supplier | You, and any second supplier |
| Certificate of analysis (COA) | What this particular batch actually was | Supplier, per batch | Retailers, importers, you |
| Safety data sheet (SDS) | Hazards, handling, transport classification | Supplier | Freight forwarders, warehouses, employers |
| Stability study | That it survives its claimed shelf life in your packaging | Supplier | You, insurers, retailers |
| Safety substantiation file | That the product is safe for its intended use | You, built from their testing | Regulators |
Spec sheet and COA are not the same document
This is the distinction worth internalising. The specification is the target: pH 5.0 to 5.5, viscosity in a stated range, fill weight 30 g plus or minus 2%, appearance and odour described. It is written once and it governs every batch.
The certificate of analysis is the measurement: this batch, made on this date, tested at pH 5.2, viscosity here, micro count below the limit. One per batch, with a batch number that matches the code on your pack.
A supplier who sends you a spec sheet when you asked for a COA has either misunderstood or is hoping you will not notice that nothing was measured. Ask again, specifically, naming the batch.
SDS, and the initialism that will not die
MSDS is the old name. The globally harmonised format has been SDS for over a decade and has sixteen standard sections in a fixed order. If you receive something calling itself an MSDS with a free-form layout, it is old, and it may predate a reformulation. Ask for a current one.
You need it more often than you would guess: freight forwarders ask before an air shipment, third-party warehouses ask before they will hold stock, and it determines whether anything in your product is restricted in transit. Alcohol content and certain propellants and essential oils are the usual surprises.
Stability is the one people skip
A stability study is what lets you print a period-after-opening symbol or a best-before date without guessing. It has to be run in your final packaging, not in a generic jar, because the container is part of the system — a formula that is stable in glass can separate or lose preservative efficacy in a particular plastic.
It takes time, which is why it gets skipped. Accelerated testing gives an indication in weeks; real-time testing takes as long as the shelf life you want to claim. Start it when you approve the formula, not when you approve the packaging, or it will be the thing holding your launch date.
What is yours rather than theirs
Safety substantiation is the one that belongs to you. Under the current US cosmetics regime the responsible person — almost certainly you — must hold records adequate to substantiate the safety of the product. You build that file mostly out of documents your manufacturer produces: the formula, the ingredient safety data, the stability work, the challenge testing, the COAs. But holding it is your obligation, not theirs, and “my manufacturer has it” is not the same as having it.
What the rules actually ask of a first-time brand, and which parts fall on the facility instead: FDA requirements for skincare after MoCRA.
Ask at the quote stage, in one line
“Which of these will you provide: specification sheet, COA per batch, SDS, and a stability study in my final packaging?” Sent with your quote request, it costs nothing and it sorts suppliers quickly. A facility with a quality system answers yes to all four in a sentence. One that hesitates has told you something useful before you spent anything — which is the same function as the seven checks, performed by a different question.
Get the answer in writing alongside the price, because all four are costs. A stability study is a real line in your batch budget, and it belongs in the plan rather than in a surprise — the seven lines a batch is made of.
Batchkind builds the document list for your category, marks which side owes each one, and shows the rule or the practice it comes from.
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