Anyone who has ever worn a dress shirt, Polo or golf style shirt knows the frustration that comes with a stubborn curling shirt collar. Usually after washing and drying a collared shirt, the collar curls up at the corners, making for an unattractive and annoying problem. Properly pressing and in some cases pinning the shirt collar are the two most effective ways for dealing with a bothersome curling shirt collar.
Lay the shirt out on the ironing board and unfold the collar. Lay the collar out flat, and in a straight line.
Iron the collar using high heat or steam until it stays flat. Flip the collar over and repeat.
Spray starch lightly on the collar and iron it again. Flip the collar over, spray starch and iron. Iron the tips of the corners as flat as you can.
Place magnetic collar stays on the shirt collar if ironing and starch is ineffective. These are available at most clothing stores where cuff links and dress shirts are sold.
Many golf apparel stores have collar stays, magnetic stays or collar pins available for Polo and golf style shirts. If your shirt is specifically intended for work or sporting events, you can have a logo patch sewn or ironed on the collars. This will prevent the collar from curling, but it will still need to be ironed properly.
Always exercise caution when using an iron to avoid serious burns. Unplug the iron immediately after use.