Four-Way Stretch Setting It Correctly on a Tech Pack
Four-Way Stretch should be written into the tech pack with a value, a tolerance and a method. This removes ambiguity from quotations.
Definition to agree
extension in both length and width. Working figures for Four-Way Stretch normally sit around 30-60% typical extension in mainstream production. Note ISO 13934-1 cyclic extension on the tech pack so nobody tests against an older revision.
Target value
Open the specification at 30-60% typical extension, adjusted to the end use. Record elastane content alongside Four-Way Stretch, because blends shift the measured value. A result outside 30-60% typical extension usually points to process drift rather than to the fibre itself.
Method line
Always pair the target with ISO 13934-1 cyclic extension so the mill and the laboratory test the same way. Keeping reference values for Four-Way Stretch lets suppliers quote without extra sampling rounds. Ask for conditioning details together with ISO 13934-1 cyclic extension, since both affect the reading.
Tolerance line
State plus or minus limits to keep production realistic while protecting the requirement. Working figures for Four-Way Stretch normally sit around 30-60% typical extension in mainstream production. Note ISO 13934-1 cyclic extension on the tech pack so nobody tests against an older revision.
Approval step
Approve the result on pre-production bulk rather than on development fabric only. Record elastane content alongside Four-Way Stretch, because blends shift the measured value. A result outside 30-60% typical extension usually points to process drift rather than to the fibre itself.
