15 · Quality Control & Testing
Week 16 · 12 hours
Objective
Define what “acceptable” means in measurable terms, arrange independent verification, and hold back payment until it’s met.
Why it matters commercially
Quality standards you didn’t write down are quality standards you can’t enforce. Once you’ve paid the balance, your leverage is zero. Inspection before final payment is the cheapest insurance in the whole business — a few hundred dollars against your entire inventory.
Core concepts
Defect classification
Every inspection needs an agreed defect taxonomy. The standard three tiers:
| Class | Definition | Footwear examples |
|---|---|---|
| Critical | Unsafe, illegal, or unsellable in any circumstance | Broken shank, exposed nail/staple, missing country-of-origin marking, mismatched pair, wrong size in box |
| Major | A reasonable customer would return it | Sole delamination, visible glue on the upper, seam skipped/broken, colour off standard, bite line visibly uneven, left/right asymmetry |
| Minor | Noticeable but tolerable | Slight loose thread, minor glue mark inside, faint scuff, small stitching wobble |
Write your own list, footwear-specific, into the tech pack. Include photographs of what’s acceptable and what isn’t wherever you can.
AQL sampling
You cannot inspect 300 pairs individually, so inspection uses statistical sampling under AQL (Acceptable Quality Limit), per ANSI/ASQ Z1.4 or ISO 2859-1. The inspector draws a sample size based on lot size and inspection level, and the lot passes or fails based on the number of defects found against agreed limits.
A common footwear standard is AQL 0 / 2.5 / 4.0 — zero critical defects tolerated, 2.5 for majors, 4.0 for minors, at General Inspection Level II. Confirm with your inspection company and state it in the PO.
The three inspections
| Inspection | When | Purpose | Cost |
|---|---|---|---|
| Initial production check | First 10–20% of the run | Catch a systemic error before the whole lot has it | $200–400 |
| During production (DUPRO) | ~40–60% complete | Verify corrections held | $200–400 |
| Pre-shipment inspection (PSI) | ≥80% produced and packed | The one that gates your final payment | $200–400 |
At 200–300 pairs, one PSI is the minimum and is non-negotiable. If your budget allows a second, add the initial production check — catching a systemic fault at pair 30 rather than pair 300 is worth far more than its cost.
Third-party inspection companies: SGS, Bureau Veritas, Intertek, TÜV, QIMA. Typically priced per inspector-day.
Write this into your PO, verbatim in substance: “Balance payment of 70% is due against (a) copy of Bill of Lading and (b) a passed pre-shipment inspection report from [inspection company] at AQL 0/2.5/4.0, General Inspection Level II, conducted at ≥80% production completion. Buyer to arrange and pay for inspection.”
Physical testing
Visual inspection catches appearance. Laboratory testing catches the failures that appear three months after your customer bought the shoe — and those are the ones that kill a young brand’s reputation.
| Test | Standard (typical) | What it protects you from |
|---|---|---|
| Sole bond / peel strength | SATRA TM404 or equivalent | Soles separating. The #1 footwear failure. Never skip this |
| Whole-shoe flex | SATRA TM92 (Bally flex) | Upper cracking and bond failure at the flex point |
| Outsole abrasion | DIN (ISO 4649) or Akron | Soles wearing through fast |
| Slip resistance | SATRA TM144 / ISO 13287 | Injury claims and bad reviews |
| Colourfastness to rubbing | Crocking test, dry and wet | Dye transferring onto socks and trousers |
| Seam strength | Seams opening | |
| Chrome VI in leather | ISO 17075 | A regulatory and skin-safety problem |
| Nickel release | EN 1811 | EU compliance on metal hardware |
| Restricted substances | REACH / your RSL | Customs seizure and liability |
Acceptance thresholds vary by construction, material and market. Do not invent numbers. Ask your test house or factory for the standard acceptance criteria for your construction type and write those into the tech pack.
A realistic minimum test package for a first run: $400–1,200. Sole bond strength, whole-shoe flex, colourfastness (dry and wet), plus chrome VI if you’re using leather. Ask your factory first — many have in-house testing and will run these for free or cheap, though third-party results carry more weight if you ever need to enforce something.
Your own testing
Free and genuinely informative:
- Wear the confirmation sample for two weeks before approving bulk. Nothing substitutes for this.
- Flex the sample 500 times by hand at the ball. Look at the bond line and the upper crease.
- Soak a scrap of upper material and rub it on white cotton, wet and dry. Crude crocking test.
- Try to peel the sole on a sacrificed sample. You did this in Module 2; now you know what good looks like.
- Leave a pair in a hot car for a day. Adhesive and foam problems surface fast under heat.
Do this
1 · Write your defect list (3h). Footwear-specific, three tiers, with photographs where possible. Add it to the tech pack as section 16.
2 · Get inspection quotes (2h). Three inspection companies, for a PSI at your factory’s location. Note cost, lead time and booking notice required.
3 · Agree the test package (2h). Ask your factory what testing they do in-house and what it costs to add. Decide your package and add the acceptance criteria to the tech pack.
4 · Amend the PO (1h). Insert the inspection-gated payment clause. Get the factory’s written agreement to it before the bulk order.
5 · Destructive test on your proto (2h). Sacrifice one shoe of the proto pair. Cut it in half, exactly as in Module 2. Compare the reality to your tech pack. This is the single best check that the factory built what you specified — and it will find at least one substitution you didn’t know about.
6 · Self-test protocol (2h). Write your own two-week wear-test protocol for the confirmation sample, with a daily log sheet.
Deliverable. A footwear-specific three-tier defect list in the tech pack; three PSI quotes; an agreed test package with written acceptance criteria; a PO amended with the inspection-gated payment clause and the factory’s written agreement; a documented destructive teardown of your own proto.
Self-check
- Define critical, major and minor defects with a footwear example of each.
- What does AQL 0/2.5/4.0 mean?
- Which inspection gates your final payment, and when in production does it happen?
- What is the most important physical test for a sneaker and why?
- Why cut your own proto in half?
Traps
Paying the balance before inspection. This is the mistake. Everything else is recoverable.
Inventing acceptance thresholds. Made-up numbers in a tech pack are worse than none — they make you look uninformed and they’re unenforceable.
Inspecting too late. A PSI at 100% packed leaves no time to rework. 80% is the convention for a reason.
Assuming the confirmation sample represents bulk. The confirmation sample is made by the factory’s best technicians, slowly. Bulk is made fast. This gap is precisely what inspection exists to measure.