just an observation. Is it in the spring, or is it because plastic is more malleable and creates stress razors easier over time?
Plastic clothes pins become brittle and break because they are an oil base product and dry up with exposure to the sun and heat.
Poor structural design. Plastic is slick and requires more spring force to hold clothes in line. To increase the force per PSI, the plastic pins should have a small stress area where the pin meets the product. The contact area should be reduced a hundred fold. Plastic structural design is faulty. To reduce production cost, the load bearing cross sectional area is too small. An I bean construction with increased web thickness should be incorporated into the plastic pin design. Unfortunately, plastic gets a bad name because the structural engineer conformised on the plastic pin design. Protective coatings are available to prevent environmental conformise. None are employed on plastic pins in order to be competitive. The question remains If a structurally competitive pin cost more than the fatigue design, would the purchasing customer select the superior design even though it cost more? If not, no matter how superior the new design, the product would go bankrupt. The follow up question is raised Does the customer select and purchase the lower cost failed plastic structure simply because the wooden design initially cost more? Do plastic pins cost more in the long run because of the higher failure rate? How can customers be intelligently informed during the selection process adequate to make an informed decision?
