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Name: Peter
Status: Other
Grade: Other
Location: N/A
Country: N/A
Date: April 2005


Question:
I like to wear shirts in the office, which I do not need to iron after washing, so called non-iron shirts. Unfortunately after a few washing cycles this property gets lost, they become wrinkled and need to iron them. I wonder, what kind of technique (chemical and/or physical treatment) is applied by the shirt manufacturers to achieve this effect and what can I do at home to make it non-iron again



Replies:
Peter,

I'm not certain but I believe the perma-press or non-iron pants and shirts are cotton blends with polyester. If so, and if the textile material has enough polyester in the blend, then the structural properties (integrity, strength, stiffness) of the material is controlled by the temperature at which polyester softens (a thing called "glass transition temperature").

So if I were to guess, I would say that repeated washing at high temperatures will bring the polyester past this glass-transition -become rubbery instead of glassy- and the press (structure) that was developed in the clothing during its production becomes gradually lost. By the way, the glass-transition temperature is not an established number; it also depends on the environment (water or solvents), stress (the washing cycle), etc.

Ironing (bringing the textile material past its glass-transition temperature) and then allowing it to cool with the structure desired (wrinkle free and with ironing seams) allows the clothing to regain its original pressed look.

Cotton does not have this ability because cotton fibers interact well with water and allows the fibers to be deformed.

So: you have a few choices, (a) wash the material at lower temperature settings, low stress cycle, weaker detergents - to reduce loss of structure (b) find clothing with more polyester in it - to strengthen structures, or (c) iron every now and then and making sure that the clothing cools in a dry, pressed state - to regain structures.

Greg (Roberto Gregorius)



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