The measurement of pull strength is a critical testing procedure in the design and manufacturing of garments in the textile world. It refers to the maximum strength that clothing buttons could withstand when they are subjected to the tensile force applied, which could result in certain degree of deformation at the place where the buttons come into contact with the fabric or lead to the detachment of the buttons from the fabric.
All buttons used for the ready-made garments should be subjected to a pull test to ensure that they can be attached securely without coming off unexpectedly. This is critically important when it comes to the buttons designed for the infants or children who may swallow them if they fall off accidentally, leading to mechanical injury.
The testing method and procedures may vary from one standard to another. And different fixtures are used based on the type of buttons, ranging from eyelets, rivets/studs, snap fasteners, snap buttons to prong snap buttons.
Below are a couple of internationally acknowledged standards which most button manufacturers and testing organizations conform to.
ASTM D7142-2/ASTM F963/ASTM PS79-96/ASTM D1776/ASTM D4846-88
EN 71-Part 1
Regardless of the testing standard or testing organization, the pull strength of buttons attached to the garments can be measured in terms of N/KG(1KG=9.8N). As per AATCC (American Association of Textile Chemists and Colorists), the buttons subjected to testing should withstand a minimum pull force of 7.72KG and stay secured and intact without unfastening, breakage or damage for 10s. Generally speaking, buttons intended for the child wear should withstand a minimum pull of 90N, while button products designed for the adult clothing should withstand a minimum pull of 70N.