Thank you for the question.It is actually a very thin coating on clothing that makes it stain-repellent. It is possible to buy stain-repellent sprays, such as Scotchgard, which you can apply to most fabrics. Unfortunately, companies keep the exact materials secret, so it is difficult to say exactly how the sprays work. I know that sprays often contain Teflon or polyurethane, as these substances are "hydrophobic," which means that they repel water. This is why many cooking pans are coated with Teflon. Typically, the hydrophobic materials exist as tiny particles mixed in a liquid which can be sprayed.