Q: Why does my zipper separate after the slider passes?
Separation behind the slider means the teeth do not stay meshed after the slider has joined them. It is a gap, alignment or tooth-form question, and watching the meshed line just behind the slider shows where the failure begins.
- Close the zipper slowly and watch the meshed line just behind the slider.
- Measure the slider gap; an opened gap releases the teeth immediately behind it.
- Check for a bent or worn tooth in the first few elements.
- Confirm the slider and chain are a matched size and type.
- Test a new slider on the same chain to see whether separation follows the slider.
Separation that follows the slider is a slider defect, and the part should be replaced and the lot checked. Separation with a good slider points to chain dimensions or a damaged tooth, and the chain should be measured against the maker's drawing before more units are sewn. Keep the failed slider for the maker to examine.