Frayed Cuffs and Collars
You can extend the lives of favorite shirts or dresses if the only problem is fraying on the cuffs or collar. Before you try this with a pair of cuffs, make sure the sleeves are long enough that they will still fit when they are ¼″ to ½″ shorter. Do both cuffs even if only one is frayed, so they'll be even. Collars must be of a style that will allow them to be reduced in size as well.
Remove the topstitching from the collar or cuffs. Cuff buttons and buttonhole stitches will have to be removed as well. Remove the inside stitching where they attach to the shirt so you can open out the collar or cuff. You may not need to remove them entirely, depending on how they were constructed. Turn the collar or cuff so the right sides are together.
Stitch around the outside edge of a collar, tapering out from the edge that attaches to the neck. You don't want to change the size of that side of the collar. Sew only across the outer side of cuffs. Trim this new seam allowance. Turn, press, and reconstruct the cuffs or collar. Replace the button, and restitch around the buttonholes.
Suit-jacket cuffs can be repaired in a similar manner. Remove the stitches at the lining and at the seam so the jacket fabric can be unfolded. Press it flat. Fold along the original crease with right sides together. Stitch close to the edge, putting the frayed area inside the row of stitches. Turn. Press the sleeve hem so the stitching is just turned to the inside. Refold the lining and blind-stitch it back in place.
Before the days of effective detergents, shirts became stained where they rubbed against the back of the neck. Homemakers used to turn these collars. That is, the collar was removed and sewn on again upside down, hiding the stain under the fold in the collar. This method will still work if that's where the collar's frayed.