It's frustrating when you buy a new dress shirt, only to discover the collar has curled after washing it. Dress shirts are intended to be worn clean and crease-free, so having the collar pushed upwards isn't acceptable. Depending on the severity of the curl, you may be able to iron it back down with a steam iron. But for severe curls, even this won't work, which is why it's recommended that you take preventive action to protect against curled collars in the first place.
Watch the Humidity
One of the most common reasons why shirt collars curl is because they are stored in a humid environment. If the humidity inside your home is above 50%, the excess moisture will settle on your shirts, causing the collars to curl. This is why it's a good idea to closely watch your home's humidity, using a dehumidifier if necessary to bring it back down.
Remove from Washer and Dryer Promptly
Another common cause of this phenomenon is failure to remove dress shirts from the washer and dryer in a timely manner. The longer you let them sit, the greater the risk of curling to the collars. So to prevent this from occurring, try to get into the habit of removing your dress shirts from the washer or dryer as soon as they are finished.
Button the Top Button
After washing and drying your dress shirts, hang them on a clothes hanger with the top button fastened. Keeping this button fastened will help your shirts maintain their shape, which should reduce the risk of curling to the collars.
Of course, we can't talk about ways to prevent shirt collars from curling without mentioning collar stays. These small, narrow pieces of metal are placed inside the shirt collar, keeping its shape and form while preventing it from curling. Some dress shirts are sold with collars stays, but even if yours did not come with them, you can usually buy them either online or at various department stores.
When in doubt, have your dress shirts professionally dry cleaned instead of washing them at hand. Washing machines can wreck havoc on dress shirts, wearing down the fabric and causing the collars to curl. Dry cleaning, on the other hand, offers a safe and effective way to clean dress shirts without causing the collars to curl. And besides, it will leave your shirts nice and "crisp" afterwards, making it well worth the minimal investment.