About Zips
Basics Structure Strength Functions Sliders Platings
A: How to Determine the Quality of a Zipper
Tape: The dye for the tape should be even without stains or scars. The tape should be soft to touch.
Teeth: The surface of the teeth should be smooth and there should be no noise when they are used.
Slider: The slider should go smoothly, freely and be secure.
Cord: The cord should fit the tape well and be secure.
Top Stop: The top-stop must come together with the first tooth on the zip. However the distance must not exceed 1mm.
Bottom Stop: The bottom stop must secure the teeth.
B: Allowable Tolerance of Zipper Length
Due to the friction caused by machinery during the manufacturing process, zippers require an "allowable tolerance". The longer the zipper the bigger the allowable tolerance will be. Industry standards are as follows:
| Zipper Length | Allowable Tolerance |
| Below 30 | ± 5mm |
| 30 - 59 | ± 10mm |
| 60 - 99 | ± 15mm |
| 100 + | ± 3% |