I was talking to an old Boy Scout buddy of mine the other day, reminiscing about the great times we spent together at summer camp in upstate New York. Eventually our conversation turned to a canoe race we were both involved in during the summer of 1978. The highlight of that race was when my buddy leaned too far going around a marker and capsized his canoe in the middle of the lake. As we were laughing about that he remembered the embroidered patch on his baseball cap curling up after his swim.
In his case, the patch curled up for two reasons. Number one, that was in the days before embroidered patches had plastic backing. And number two, when he sewed it on his ball cap he only used four single stitches.
Embroidered patches today are not likely to curl up unless they are exposed to excessive water followed by excessive heat. The plastic backing (especially on die-cut patches) takes care of that. But if you're using patches without a plastic backing they are still susceptible to curling if the garments they are attached to are exposed to the weather. To prevent curling there are couple of things you can do.
First off, if the patch is already attached to a piece of clothing, just run an overcast stitch around the entire perimeter. If you use the same color thread as the border, and you keep the stitch tight, no one will ever see it. If the patch hasn't yet been attached you can purchase some special glue at your local craft store to apply around the border. The glue should be sufficient to prevent curling in the future. And even if it does curl you still have the option to stitch it down.
