--Photo by Gendo Taiko
If your taiko head looks like this, it's over. Stop using it.
This is a picture of a 100% handmade, makeshift shime drum (as you can tell from the flimsiness of the base).
Turned out the skins weren't too strong either, resulting in tears. As you can also see, the skin underwent several surgical procedures to try to bring it back to normal, but with limited success. When a drum head tears, or you get a hole in it, you'll never recover the sound, and you won't be able to tighten it as hard. Hence the need to replace it.
However, there are times when buying/making a brand new head isn't an easy option, and if possible, you want to continue using the torn head. Full recovery is impossible, but you can give it some first-aid care if you want to salvage it.
Here's what you need:
1. Twine (synthetic or natural, stronger the better)
2. Stitching needle (strong one used for leathers)
3. Leather punch
4. Wet towel
With those items, you can stitch your head back together again. Here's how to do it:
1. Using a towel, wet the area that contains the tear. You want to avoid wetting the entire head, focus just on the area around the tear. Wet it until the area becomes soft and flexible. You may need to let the towel sit on the area for a while for it to be sufficiently moist.
2. Using a leather punch with holes that match the width of your needle/twine, punch holes along both sides of the tear. Punch holes so that they are spaced evenly, and no more than 1cm away from each other.
3. Thread the twine into your needle, and begin stitching. Make a nice strong knot on your first stitch to keep the thread in place.
4. While threading, pull the twine tight so that gap of the tear closes. Be careful though- pull too strong and you might cause another tear. If the skin is sufficiently wet, it shouldn't require much strength.
5. After the final hole, tie the twine in such a way that the thread doesn't come loose. I usually tie it tight to one of the previous stitches.
6. Now you're done with the stitching. Let the skin air dry for a few days and you'll be good to go.
And that's it.
Note: You can't use the stitched head for playing any more (it'll mess with the stitches, and it simply won't sound good). Keep the stitched head on the back side (non-playing side). It can't be used for playing anymore, but without it, you can't tighten the shime drum, so it'll still serve a purpose.