# Creases in wrinkle-resistant shirts **URL:** \ **Category:** Factual Questions\ **Created:** [December 18, 2006, 4:58pm UTC](https://boards.straightdope.com/t/creases-in-wrinkle-resistant-shirts/384652 "2006-12-18T16:58:52Z")\ **Posts on this page:** 3\ **Page:** 1
**Author:** ![CookingWithGas](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/cookingwithgas/32/485_2.png) [@CookingWithGas](https://boards.straightdope.com/u/CookingWithGas)\ **Post date:** [December 18, 2006, 4:58pm UTC](https://boards.straightdope.com/t/creases-in-wrinkle-resistant-shirts/384652/1 "2006-12-18T16:58:52Z")
I have a few shirts that are 100% cotton and billed as wrinkle-resistant (and they really are). What I can’t figure out is how the creases are permanent. How do they get the creases in? Conventional ironing won’t do this. ---
**Author:** ![Colophon](https://avatars.discourse-cdn.com/v4/letter/c/f05b48/32.png) [@Colophon](https://boards.straightdope.com/u/Colophon)\ **Post date:** [December 18, 2006, 5:16pm UTC](https://boards.straightdope.com/t/creases-in-wrinkle-resistant-shirts/384652/2 "2006-12-18T17:16:12Z")
Are they definitely 100% cotton? In my experience most crease-resistant shirts contain a small amount of polyester in the fabric. I always assumed that the creases were put in with a device hot enough to slightly melt the polyester into shape, but I could be wide of the mark with that one… ---
**Author:** ![According\_to\_Pliny](https://avatars.discourse-cdn.com/v4/letter/a/8e7dd6/32.png) [@According\_to\_Pliny](https://boards.straightdope.com/u/According_to_Pliny)\ **Post date:** [December 19, 2006, 11:03pm UTC](https://boards.straightdope.com/t/creases-in-wrinkle-resistant-shirts/384652/3 "2006-12-19T23:03:13Z")
Just heat and pressure. Probably the pressure is the real key, since when you overheat at home you (that is I) get scorch marks.