Trims quality control is the cheapest point at which to stop a problem. A loose snap, a zip that catches or a label in the wrong colour costs pennies while it's still in the carton – and hundreds of euros once it's sewn into a run of 500 garments or returned by a customer. This article explains how brands and factories check trims in two places, on arrival and in the finished garment, which tests they use and how much to sample.
The two checkpoints
- Incoming trims inspection – before anything reaches cutting and sewing. You check that what arrived matches the approved sample: quantity, size, colour, function and paperwork.
- Finished garment inspection – during production and at the end. Here you check how the trim has been attached: is the button sewn securely, is the snap set correctly, is the zip inserted straight?
Many problems that look like "a bad trim" are really fitting problems – a snap set with the wrong die, for example. That's why the two checkpoints work together.
Classic sew-on snap buttons SP517 – 15 and 23 mm Nickel Free
Snap fasteners E-2278 Gun Metal 40 mm – 4 pieces, "Teardrop" design, Luxury model
Metal buttons with a pink finish 6104047 Col 255 – 22 mm handmadeIncoming inspection: what to check
| Check | How | Typical problem |
|---|---|---|
| Quantity and packing | Carton count, carton labels, spot check of packs | Shortages, mixed colours in one pack |
| Size | Calipers: button diameter in mm/ligne, zip length, elastic width | An 18 mm button instead of 20 mm, a zip 1 cm short |
| Colour | Compare with the approved sample in a D65 light box | Shade variation between lots |
| Function | Open/close, slide, stretch | Zip catches, snap doesn't click |
| Appearance | Visual check for scratches, rough edges, marks | Sharp edges, peeling plating |
| Paperwork | Test reports, certificates | No nickel test report for a kidswear run |
The pull test: buttons and snaps
A pull test checks that a trim will stay on the garment under real-world load. It matters most in childrenswear, where a detached small part is a choking hazard.
- How it's done: the trim is gripped with a clamp attached to a force gauge, the fabric is held fixed and a force is applied and held for about 10 seconds.
- What force: set by the buyer's specification. As a guide, inspection companies use around 50 N for small parts, while children's garments usually call for more – often 70–90 N.
- Pass criteria: the trim must not detach, loosen or tear the fabric. For snaps, the unsnapping force is also measured, using a separate method (ASTM D4846).
Tip: run pull tests on finished garments from the actual run, not on a fabric offcut. Fabric weight and density change the result more than the button itself.
Zips: cycles, action and strength
During garment inspection, each zip sampled is opened and closed about 20 times. You're looking for catching, splitting behind the slider, missing teeth, loose stops and – on auto-lock sliders – whether the lock actually holds. In the lab, zips are tested more thoroughly: lateral chain strength, slider pull-off force and resistance to repeated opening. The European specification for zips is EN 16732.
A common source of complaints isn't the zip itself but how it's sewn in: stitching too close to the teeth, stretched tape that ripples, or lining that gets caught in the slider.
Colour and colourfastness
- Match: assessed in a light box against the approved lab dip or sample, under D65 and a second source to catch metamerism.
- Fastness to washing and rubbing: tested under the ISO 105 series (e.g. C06 for washing, X12 for rubbing). Results are graded on a 1–5 grey scale; for apparel the usual requirement is grade 4 or better.
- Colour migration: especially dark elastics and tapes on light fabric – check by washing a finished garment.
AQL: how many pieces to check
You rarely check everything. ISO 2859-1 sets out a sampling plan (AQL) based on lot size. General inspection level II is the most common:
| Lot size (pcs) | Sample | Major defects accepted (AQL 2.5) | Minor defects accepted (AQL 4.0) |
|---|---|---|---|
| 281–500 | 50 | 3 | 5 |
| 501–1,200 | 80 | 5 | 7 |
| 1,201–3,200 | 125 | 7 | 10 |
| 3,201–10,000 | 200 | 10 | 14 |
If the defect count exceeds the acceptance number, the lot is rejected or goes to 100% inspection.
Defect classes
- Critical – a safety risk or legal breach: a snap that pulls off a babygrow, a sharp edge on metal hardware, a cord in the neck area of young children's wear. The usual acceptance level is zero.
- Major – the garment doesn't work or can't be sold as first quality: a zip that won't close, the wrong colour, the wrong button size.
- Minor – cosmetic, doesn't affect use: a small scratch on the inside, an uneven thread on a label.
Incoming inspection checklist
- Approved sample and spec in the inspector's hands.
- AQL sample drawn from different cartons.
- Size with calipers, colour in a light box.
- Function test: 20 cycles for zips, click for snaps, stretch and recovery for elastic.
- Pull test on 3–5 finished garments from the first pieces.
- Nickel (REACH) paperwork and, where needed, OEKO-TEX.
- A written report with a decision: accept, reject or re-sort.
Recording results and feeding back
Inspection is only worth something if the results reach the supplier. For every lot, record the date, order number, sample size, defect count by class and photos of every major and critical defect. Keep one sample from each accepted lot – if a complaint comes in months later, you'll have something to compare against. A good supplier prefers a clear report to a vague "we're not happy": it lets them find the root cause and fix it in the next lot.
Trims from Bul-tex
Bul-tex manufactures and supplies garment trims – buttons, snap fasteners, zips, labels and elastics. Before placing a production order you can ask for samples to test on your own fabric. For runs with specific inspection requirements, get in touch. More manufacturing guides are in our production articles.
