Define before you quote
How to write a product specification sheet for a Chinese factory
The specification sheet is the shared definition of what is being quoted, sampled, produced, inspected, and accepted. If a requirement matters after production, it should be identifiable before the supplier prices the job.
- Editorial status
- Source-checked buyer guide
- Last reviewed
- Prepared by
- AllForSourcing Editorial Desk
Research basis: Manufacturing and procurement guidance from ISO, NIST, and the UK government, translated into a buyer workflow for cross-border production.
Boundary: This guide does not select product standards, tolerances, test methods, or market-access requirements for a specific model. Those decisions require product and destination-market expertise.
Direct answer
A useful spec closes decisions; it does not collect adjectives
“High quality,” “premium material,” and “same as sample” sound clear in conversation but do not define an acceptance test. A factory needs measurable requirements, named references, approved alternatives, and a rule for changes.
A good first version does not need to be a 40-page engineering package. It needs enough controlled detail for three suppliers to quote the same product and for an inspector to decide whether one finished unit conforms.
The minimum viable specification
| Section | What to define | Evidence or reference | Common failure |
|---|---|---|---|
| Document control | Product ID, revision, owner, issue date | Versioned PDF and revision log | Factory quotes an obsolete attachment |
| Intended use | User, environment, performance outcome | Use cases and excluded uses | A technically similar product is unsuitable in use |
| Geometry | Dimensions, tolerances, interfaces, weight | Numbered drawing or CAD reference | Nominal dimensions are treated as approximate |
| Materials | Grade, formulation, hardness, thickness, approved substitutes | Standard, data sheet, colour code, approved sample | “Equivalent” material is substituted without approval |
| Appearance | Colour, gloss, texture, print, workmanship limits | Master colour, artwork file, defect board | Cosmetic expectations exist only in chat |
| Performance | Load, leak, cycle, temperature, fit, electrical or other tests | Test method and acceptance value | Supplier chooses a test that cannot answer the buyer’s question |
| Packaging | Unit pack, carton, labels, barcode, protection, pallet | Dieline, packing drawing, carton-mark file | Product passes QC but arrives damaged or unfulfillable |
| Inspection | Defect classes, sample plan, checks, release gate | Inspection checklist and approved sample ID | Inspection finds a defect nobody agreed was rejectable |
Write requirements that survive translation
Too vague
“Strong retail box, premium printing, no scratches.”
There is no board grade, compression expectation, artwork revision, colour target, scratch definition, viewing distance, or sampling rule.
Controllable
Name the material, drawing, test and limit.
Reference the approved dieline and artwork revision; define board construction; specify the agreed compression or transit test; classify visible print defects with an approved sample or defect reference.
- Use one requirement per line.It is easier to translate, answer, revise, and inspect than a paragraph containing several conditions.
- Give every drawing a number.“See attached” becomes ambiguous as soon as two files have similar names.
- State the unit.Dimensions, force, temperature, colour tolerance, weight and time require explicit units and test conditions.
- Separate shall from may.Mandatory requirements, supplier proposals and optional features should not look the same.
- Ask suppliers to mark exceptions.Silence is not acceptance. Require a line-by-line deviation list with the quote.
The sample needs an identity
“Same as approved sample” is only useful when everyone can identify the same object. Give the retained sample an ID, approval date, photos, revision, signer, and custody location. Then state which attributes the sample controls and which remain controlled by drawings, test methods or written limits.
Example sample record
- Sample ID
- AFS-27 / Revision B / Unit 02
- Controls
- Exterior colour and texture; logo position; assembled fit
- Does not control
- Material chemistry; internal dimensions; packaging; regulatory compliance
- Custody
- One signed unit held by buyer; one sealed unit held by supplier
Add a change-control sentence before the purchase order
Many disputes begin with a change the factory considered harmless: a resin grade, adhesive, sub-supplier, coating, chip, connector, packaging board, process temperature, or production site. List the changes that require written buyer approval and require the supplier to explain the reason, affected lots, timing, validation evidence, and price or schedule impact.
Working language: “No material, component, sub-supplier, production site, tooling, process, artwork, packaging or test-method change affecting the approved specification may be introduced without the buyer’s written approval of a documented change request.” Adapt the clause with qualified contract advice where needed.
Issue the specification as a quotation control
- 01
Freeze a dated PDF revision. Keep editable source files under buyer control.
- 02
Send the same revision and commercial quantity scenarios to every supplier.
- 03
Require a compliance matrix: comply, exception, proposed alternative, or information needed.
- 04
Record every approved clarification in the next revision; do not leave binding decisions in chat.
Public source citations
ISO 9001 in the supply chain
iso.org | standards organization guidance | checked 2026-07-15
SPEC-02NIST Manufacturing Extension Partnership supplier scouting request fields
nist.gov | official manufacturing program | checked 2026-07-15
SPEC-03NIST: Tolerance Specification and Related Issues for Additively Manufactured Products
nist.gov | government research | checked 2026-07-15
SPEC-04UK government guidance on technical specifications
gov.uk | official procurement guidance | checked 2026-07-15