Shoe upper defects: scratches, stains, creases and holes
The upper is the first thing a customer sees, so it's where a small defect costs the most. Many upper defects don't start at final inspection: they come from the leather or material itself, from cutting, or from handling between operations.
Scratches on the upper
What it is. Linear marks on the surface of leather or synthetic material, from faint to deep.
Where it starts. Some come from the hide itself, as natural scars and scratches that weren't avoided at cutting. Others come from tools and work surfaces, or from handling between cutting, closing and lasting.
Why inspection misses it. A fine scratch only shows when light hits it at a certain angle, and on textured or glossy leathers it blends into the grain.
How to prevent it. Inspect hides before cutting and mark the areas to avoid, keep tables and conveyors clean and free of sharp edges, protect components between operations and inspect under consistent, low-angle light.
Stains on the upper
What it is. Marks from adhesive, oil, water, dye or fingerprints that change the colour or sheen of the upper.
Where it starts. Adhesive application, oily machinery, handling with dirty or damp hands, and cleaning products that don't suit the material.
Why inspection misses it. On light colours a faint stain is easy to miss, and some only appear once they've dried.
How to prevent it. Control how much adhesive goes on and where, keep machines clean, wear gloves at critical stations, test cleaning products on each material and inspect after drying.
Creases in the upper
What it is. Wrinkles or folds in the upper that remain after lasting.
Where it starts. Uneven tension over the last, poor skiving, insufficient heat setting, or material stored folded.
Why inspection misses it. Many creases only show once the shoe comes off the last, or hide in flex areas such as the vamp.
How to prevent it. Set lasting tension correctly, control skiving and heat setting, and store hides and materials flat.
Holes in the upper
What it is. Punctures or weak spots in the upper that aren't part of the design.
Where it starts. Natural hide defects, needle holes outside the stitch line, or tool damage during cutting and lasting.
Why inspection misses it. They're often small and sit next to seams, folds or decorative perforations, where the eye reads them as part of the design.
How to prevent it. Inspect hides before cutting, check needles and cutting tools, and look closely at the areas next to seams.
How TreadlyAI helps
Photographing the shoe right after the stage where these defects start helps catch them before they move down the line. TreadlyAI highlights the defect area, records every inspection and alerts you when defects pass the limit you set, so you can fix the cause and not just the pair.
Other areas of the shoe
- Stitching: Loose or skipped stitches, thread ends on show and uneven seams. Cosmetic defects that can open up with wear.
- Bonding: Glue past the bonding line and soles that come apart. A multi-step process where every step counts.
- Sole: Cracks, scratches and warped soles. Defects that come from the material, from storage or from assembly.
- Finishing: Mould marks, uneven paint and dirt. The last chance to catch a defect before the box.
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