Sourcing custom bags looks simple until the first shipment arrives. The bags are a slightly different shade, the handles are stitched narrower than the sample, the fabric feels thinner than what you approved, and the supplier’s answer is that this is normal production variation. At that point you discover what your due diligence was actually worth.
This is a guide to doing that due diligence before the money moves. It is written by a supplier, which you should factor in — but everything below is checkable, and most of it is what a competent buyer would work out after two or three painful orders.
Start by being honest about what you are buying
There are three kinds of supplier in this market and each has a legitimate place.
A direct factory owns machines and staff, and is genuinely good at the narrow set of products those machines make. Ask a non-woven bag factory for canvas totes and paper bags and it will quietly subcontract them, usually without telling you.
A trading company owns no production and buys from whoever is cheapest that month. The good ones add real value in communication, quality management and consolidation. The bad ones add a margin and a layer of distance between you and the person who can actually fix a problem.
A sourcing partner with a core production base sits in between: a primary factory relationship for the main product line, plus vetted partner factories for adjacent categories, with one team accountable for the whole order. That is our own model — non-woven production runs in an SGS-verified facility in Wenzhou, and canvas, paper and film products are produced through partner factories under the same specification and inspection discipline.
None of these is inherently better. What matters is that you know which one you are dealing with. A supplier who is evasive about it is telling you something.
Verify the company actually exists
This sounds obvious and it is routinely skipped.
Ask for the business licence. Every registered Chinese company has one, with a unified social credit code. The registered scope tells you whether the entity is licensed for manufacturing or only for trade, and the registered capital and establishment date tell you how long it has existed.
Ask for third-party verification. An SGS, TÜV, Bureau Veritas or Intertek supplier assessment means an inspector physically attended the site and confirmed what is there. This is materially stronger evidence than photographs, which can be anything. Ask for the report, not a badge on a website.
Do a live video walk of the floor. Not a pre-recorded film. Ask them to walk from the raw material store through cutting, printing, stitching and packing, in one unbroken take, and to show you the machine nameplates. It takes fifteen minutes and it settles the question.
Check that the addresses agree. Business licence address, the address on the quotation, the shipper on past bills of lading, and the location in the video should be consistent. Where they are not, there is an explanation, and you want to hear it.
The questions that separate a supplier from a broker
You do not need to be a manufacturing expert. You need to ask questions whose answers require operational knowledge.
What fabric weight would you recommend for this use case, and why? A supplier who answers “whatever you want” is not engaged with your problem. A good answer contains a trade-off — this weight for this load, at this cost, with this consequence for print.
Which print method are you quoting, and what is the setup cost? If tooling is not itemised, it is either buried in the unit price or has not been thought about. Both are bad.
What is your in-line inspection interval, and what happens when a check fails? The answer should describe a procedure, not an intention.
Can I nominate my own third-party inspector? Hesitation here is the single most informative reaction in the whole conversation.
What are the carton dimensions, pieces per carton and gross weight? A factory knows this without checking. It also changes your landed cost, so you want it early.
Read the quotation properly
A price on its own is not a quotation. What you need to see is what the price is a price for.
Material and fabric weight in gsm or ounces. Finished dimensions including gusset, stated as width by height by gusset. Handle type, length and attachment method. Print method, number of colours, print area and number of faces printed. Lamination if any. Packing method, pieces per polybag and per carton. Tooling and sampling charges as separate lines. The Incoterm the price is quoted on. The production lead time and what it is measured from.
When two quotations differ by a wide margin, almost always one of those lines differs too. The 20 gsm difference in fabric weight that nobody mentioned, or a single-face print quoted against a double-face requirement. Line them up side by side before you conclude that one supplier is expensive.
Be equally wary of the quote that is far below the others. Fabric weight, stitch density and handle reinforcement are the three places where cost is quietly removed, and all three are invisible in a photograph.
The sample stage is the real due diligence
Everything before the sample is conversation. The sample is evidence.
Order a pre-production sample made to your final specification, and when it arrives, measure it. Width, height, gusset, handle length, handle width. Weigh it and check the fabric weight against what was quoted — a gsm cutter and a precision scale is how the factory does it, but a kitchen scale and arithmetic will catch a serious discrepancy. Load it with the weight it is meant to carry and lift it by the handles thirty times. Look at the print under daylight, not office lighting, and against your Pantone reference.
Then keep it. The approved sample and the signed specification sheet together are the reference for the pre-shipment inspection, and they are what any dispute is settled against. A supplier who does not want a signed specification on file is a supplier planning to argue later.
Structure payment to reduce your exposure
Bank transfer with a deposit at order confirmation and the balance against shipping documents is the market standard, and it is reasonable for both sides — the factory has bought material and committed machine time, and you have not yet seen the goods.
What makes it safer is the sequencing. Release the balance against a pre-shipment inspection result, not against a promise. If the order is large enough to warrant it, appoint a third-party inspection company; the cost is small relative to a container of unusable bags. For a first order with a new supplier, consider splitting the volume — a smaller initial run tells you a great deal for a fraction of the exposure.
Red flags
A price far below every other quotation. Nobody in this industry has a secret cost advantage of thirty percent. Something has been removed from the specification.
Reluctance to allow inspection or a factory visit. There is no good reason for this.
No written specification sheet. If it is not written down, it is not agreed, and you will discover the difference at the port.
A published minimum order quantity that never changes regardless of product. An unprinted ultrasonic-welded bag and a full-colour laminated bag have entirely different economics. A single site-wide number means nobody has costed your job.
Certificates supplied as images. Ask for the certificate number and the issuing body, and check it against the issuer’s register.
Claims that cannot be evidenced. “Certified compostable”, “food safe”, “recycled content” and similar are testable statements. If a supplier makes them casually without asking which standard you need, they are not thinking about your regulatory exposure — and it is your brand on the bag, not theirs.
Communication that degrades after the deposit. Response time during production is the best available proxy for how a problem will be handled.
A checklist you can work through
Before requesting quotes: define the use case, the load the bag must carry, the quantity range, the destination, the date you need stock, and whether the artwork is ready.
Before choosing a supplier: business licence checked, third-party verification report seen, live video walk completed, addresses consistent, itemised quotation received, tooling and sampling costs stated separately, carton data provided.
Before paying a deposit: specification sheet signed by both sides, dieline issued and artwork approved on it, sampling scope and cost agreed, payment terms and Incoterm in writing, inspection arrangement agreed.
Before releasing the balance: pre-shipment inspection completed against the signed spec, AQL result reported, packing and carton marks verified, shipping documents checked.
Our own version of that sequence is set out stage by stage in how it works, and the inspection detail is in quality and compliance.
Frequently asked questions
How do I know if a supplier is a factory or a trading company?
Check the business scope on the business licence, ask for a live unedited video walk of the production floor, and ask a specific process question — inspection intervals, machine count, stitch density. A trading company will answer in generalities because it is relaying, not operating. Note that being a trading company is not disqualifying; concealing it is.
What does an SGS verification actually prove?
That an independent inspector attended the site and verified the company’s existence, scale and stated capability at the time of assessment. It is not a quality guarantee for your order, and it does not replace inspecting your own goods. It does establish that the entity you are dealing with is real and operates where it says it does.
Should I always ask for the lowest price?
No, but you should always ask why a price is what it is. Compare specification lines rather than totals. The cheapest quote in a set is usually cheapest because something was removed, and fabric weight is the first thing to go.
Is a physical sample worth the cost?
Almost always. A pre-production sample costs a small fraction of a production run and is the only way to test the specification against reality before committing. It also gives you the reference object for the pre-shipment inspection.
What payment terms are normal?
A deposit at order confirmation with the balance against shipping documents is standard for bank transfer. Requests for full payment up front on a first order are unusual and worth questioning.
Can I send my own inspector?
You should be able to. Buyer-nominated third-party inspection is routine and a supplier who resists it is telling you something important about how the shipment will look.
Next step
If you want to test the process described here, start with a real enquiry rather than a general one: the bag, the load it carries, the quantity range and the destination. You will get an itemised specification and a price you can interrogate. Request a quote.
Buyer Summary
A useful supplier comparison is based on the same written specification and approval standard, not the lowest headline unit price. Check how each factory controls materials, samples, production changes and pre-shipment inspection.
Related Sourcing Resources
Frequently Asked Questions
- What should buyers verify before selecting a manufacturer?
- Verify legal identity, production capability, material control, sampling process, quality records, export experience and communication ownership.
- Why should quotations use the same specification?
- Without matching dimensions, GSM, handles, printing, reinforcement and packing, lower prices may describe a materially different bag.
- Is a pre-production sample necessary?
- Yes. It establishes the approved standard for dimensions, material, construction, artwork and finishing before bulk production.
Prepared by the Global Bag Supply sourcing team · Updated August 8, 2026
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