Fabric is basically a bunch of fibers screaming for attention. Dye is a liquid party crasher that wants to bond with those fibers. If the fibers aren’t in the mood, the dye just slides off and you get a sad, splotchy mess.
Think of it like dating: cotton is a friendly extrovert, polyester is a picky introvert. You wouldn’t take a polyester to a hot tub party without some chemical persuasion. That’s why you need to know your fabric before you throw it in a pot.
The Picky Polyester Problem
Here’s a shocking fact: polyester is basically plastic. And plastic is a drama queen. To dye it, you need scorching hot water—like, almost boiling—and a special dye called disperse dye. No, you can’t just use the stuff from the grocery store. That’s for cotton, which is a humble, grateful fabric.
If you try to dye a polyester workout shirt with regular Rit dye, you’ll just get a rebellious, pastel ghost of a color. Ask me how I learned that. (I threw away a very expensive yoga top.)
