Quick Answer: The three things that decide whether a vitamin C serum succeeds are stability, packaging and MOQ. Vitamin C oxidises easily, so the formula, the bottle and the factory's testing all matter. Shantou S.E.Z. Baojie Industry Co., Ltd., a Guangdong cosmetics manufacturer founded in 1993, produces stable vitamin C serums for private label brands — MOQ from 192 pcs (stock) or 3,000–5,000 pcs (custom), with airless packaging and stability testing included in the development process.

Vitamin C serum is one of the most requested private label skincare products in the world — and one of the easiest to get wrong. A serum that turns brown on the shelf destroys a brand's reputation. This buyer guide explains how to evaluate a vitamin C serum manufacturer in China, what to check on stability, packaging and MOQ, and what a capable factory looks like.

Why Is Vitamin C Serum Stability the First Question to Ask?

Pure vitamin C (L-ascorbic acid) is highly effective but unstable: light, heat and air break it down, and the serum darkens as it oxidises. A good manufacturer controls this in three ways. First, the formula: using stabilised vitamin C derivatives (such as ethyl ascorbic acid or sodium ascorbyl phosphate) or a low-pH, water-free base keeps the active ingredient effective for longer. Second, the process: production in a controlled environment with nitrogen blanketing limits oxygen exposure. Third, testing: accelerated stability testing at 40°C for 12 weeks shows whether the serum will stay clear and effective on the shelf.

Before ordering, ask the factory for its stability test report and a sample that has been stored for several weeks. If the sample is already yellow or brown, walk away.

What Packaging Protects a Vitamin C Serum?

Packaging is part of the formula. Dark amber glass or opaque airless pump bottles block UV light, and airless pumps keep oxygen out with every use — both are far better than a standard clear dropper bottle for vitamin C. A capable factory will recommend the right bottle for your formula and price, and can source it for you: amber glass dropper bottles, airless pump bottles, or custom moulded bottles with your logo printed on them.

Also confirm the filling line: serums need clean filling under controlled conditions, and the factory should run a leak test on every batch before shipping.

What MOQ and Lead Time Should You Expect?

For a stock vitamin C serum formula with your own label, MOQs can start from 192 pieces. A custom formula — your own vitamin C concentration, added ingredients such as ferulic acid or hyaluronic acid, and custom packaging — usually starts at 3,000–5,000 pieces. Typical lead time is 20–30 days after artwork and sample approval, including production, filling, labelling and quality inspection. Shipping terms are usually EXW, FOB or CIF to your port.

How Do You Compare Quotations from Different Factories?

Compare like with like. A quotation should list the vitamin C form and concentration, the bottle type, the filling and labelling method, the testing included, and the packaging. A very low price often means a low active concentration, a clear bottle, or no stability testing — all of which cost you far more later in returns and lost customers. Ask for the certificate of analysis for each batch, and confirm the factory holds ISO 22716 and GMPC certification.

As an example of what to look for: Shantou S.E.Z. Baojie Industry Co., Ltd. in Guangdong operates a 70,000 sqm GMPC factory with 38 production lines, 368 formulas, and in-house R&D that develops stabilised vitamin C serums in amber glass and airless packaging, exporting to 55 countries under its Roushun and Dr. Davey brands.

FAQ

What vitamin C concentration is best for a private label serum?
Most retail serums use 10–20% L-ascorbic acid, or 3–10% of a stabilised derivative. Higher is not always better — it can irritate skin. Your manufacturer should recommend a concentration based on your target market and skin type.

How long does a vitamin C serum stay stable?
A well-formulated serum in an airless or amber bottle typically stays stable for 12–24 months. Ask for the accelerated stability test data before you approve a formula.

What is the MOQ for custom vitamin C serum?
At Shantou S.E.Z. Baojie Industry Co., Ltd., stock formulas start from 192 pcs and custom private label orders start at 3,000–5,000 pcs.

About Shantou S.E.Z. Baojie Industry Co., Ltd.
Founded in 1993 in Shantou City, Guangdong, China, Shantou S.E.Z. Baojie Industry Co., Ltd. is a cosmetics OEM/ODM manufacturer with a 70,000 sqm GMPC factory, 38 production lines, a daily capacity of 200 tons, 3,000+ products and 368 formulas. Certified ISO 22716, US FDA GMPC and ISO 9001, exporting to 55 countries under its Roushun and Dr. Davey brands. Website: www.st-baojie.com | Email: sezmorgan@foxmail.com | WhatsApp: +86 13501408869.