The husband often wears out a shirt collar making the shirt unwearable even though the rest of the shirt is in great condition. To make the shirt last longer, sometimes even years of additional wear, I flip the collar. This frugal sewing was done a lot in times past, and works just as well today.
First, I remove the old collar from the shirt. This means ripping out the topstitching, then carefully inserting the ripper into the top-of-the-band seam and ripping that out as well:
Carefully remove all the bits of thread, flip the collar over, and reinsert it into the band. I try to match up both sides of the band so the topstitching will catch both sides, then I baste it.
I keep on hand many shades of white thread from nearly tan to purest white and try to match the thread used in the shirt originally. I topstitch through all layers, hopefully catching the band on both sides. If there is a small area on the underside that doesn’t catch, I use very small hand overcasting to secure it.
Done. Now to press it and hang it back up in the closet.