Why is the zip is curved / humpy after stitching continuous zip chain to the product?
Spiral / coil zips have an S twist and Z twist in the teeth creating a ‘smile’ or ‘frown’ appearance when the teeth are joined. The left and right teeth should be both in the same direction/condition. If this is not the problem, check the sewing tension is equal on both sides of the zip.
Why is the slider sticking / jamming on the chain after insertion?
Check that there is sufficient clearance for the slider to pass along the length of the zip. Check that there is no adhesive accidentally applied to the zip teeth or inside the slider during insertion. Check that no side seams interrupt the travel of the slider along the chain. Recommended distance is 2mm from the […]
Why are there stain marks to be found on the fabric adjacent to the zip?
Check for any solution / sprays / polishes being used on the zip teeth. Check for any excess oil being used on sewing threads if sewn application or check temperature of heat seal if sealed zip application.