Knit Fabric Quality Inspection: Using the Four-Point System (AQL 4.0)

Fabric inspection is where most quality problems can still be corrected cheaply. Once the fabric is cut, the options are limited to sorting, discounting or scrapping. A disciplined inspection standard is therefore one of the highest-return controls a buyer can insist on.

The four-point system in brief

Defects are assigned points according to their length or size, regardless of type:

• Up to 7.5 cm – 1 point
• 7.5 to 15 cm – 2 points
• 15 to 23 cm – 3 points
• Over 23 cm – 4 points
• Holes and openings, regardless of size – 4 points

Each roll is inspected across its full width, usually at a viewing distance of about one metre under defined lighting. Points are totalled per roll, then converted to points per 100 square yards using the roll length and width.

Acceptance levels

• Points per 100 square yards – 20 or below is a common target for quality knits; 20–30 is acceptable for some programmes; above 40 should trigger rejection or negotiation.
• Individual roll limit – no single roll exceeding about 20 points is a practical rule.
• Critical defects – holes, needle lines, oil stains, wrong shade or width are usually rejection defects independent of point totals.

Common knit defects to watch

• Needle lines and vertical streaks from damaged needles or yarn tension.
• Barre marks caused by yarn lot variation or inconsistent feed.
• Drop stitches, holes and runner damage.
• Dye spots, uneven dyeing and centre-to-selvedge shade variation.
• Contamination with foreign fibres, most visible on dark shades.
• Width and GSM variation beyond the agreed tolerance.

Process recommendations

• Inspect 100% of rolls for critical defects and random 10% for points, or 100% if the program is high value.
• Record inspection results with roll numbers so any cut panel can be traced back.
• Issue a corrective action request with photographs for every failed lot.
• Review inspection data monthly with the mill to identify recurring causes.
• Keep reference samples of approved shade and hand feel for comparison.

Inspection is not an accusation; it is a shared measurement. Mills that receive structured feedback improve faster, and buyers who inspect consistently get better fabric at the same price.