The gi, sometimes called dogi, is the traditional uniform of the Japanese and Okinawan martial arts. A traditional gi consists of a white, long-sleeved, kimono-style jacket and white drawstring trousers. Modern gi sometimes incorporate piping or stripes. They come in black or blue, or even red or flag patterns. Modern gi can also sport patches representing the style, school, rank, role, or country of the wearer. Sewing a patch on a gi is a simple process requiring few tools.
Consult with your organisation about the appropriate locations for your patches. Most schools have specifications for exactly where the patches should be worn. Most also ban unapproved patches.
Measure to find the correct location for the patch. Pin it to the gi using two or three pins.
Put on your gi and your belt. Be careful not to stick yourself with the pins or knock the patch loose. Check the patch in the mirror or have your assistant check it for you. Make sure the patch is straight, shifting it slightly if necessary. Add a couple of more pins to make sure the patch doesn't move while stitching.
Thread the needle with about 2ft. of thread. Knot one end of the thread. Leave an ample amount of the unknotted end of the thread hanging from the other side of the needle,
Insert the needle from the inside of the gi at the edge of the patch. Pull all of the thread to the outside of the gi, checking to make sure the knot is holding on the inside. Catch a small amount, about 1/16 in., of the underneath side of the edge of the patch with your needle. Pull the thread through. Insert the needle back into the gi just under your stitch on the edge of the patch. Insert the needle from the inside of the gi about 1/8 to 1/4 in. from the first stitch. Repeat the process until you have gone all the way around the outside edge of the patch.
Remove all the pins.
If your patch is worn on the right or left breast of the jacket, it is especially important to check to make sure the patch is straight while wearing the jacket and your belt. What looks straight when your jacket is laid out on a table rarely looks straight when you are inside the jacket. When catching the edge of the patch with your needle, don't poke all the way through the patch, just pick up a small amount of the edge stitching. Also keep your stitches underneath the edge of the patch as much as possible. The goal is to have as few stitches as possible show when wearing your gi.
If you compete in tournaments, check the administrators' requirements before sewing on patches. Some tournaments will not allow you to wear an organizational patch while you are competing. If the gi or the patch is extra heavy, you may need to use a thimble to push the needle through the fabric.