1. Locate the puncture. Assuming that you have already removed the tube, inspect it and locate the puncture. It can usually be found easily by pumping air into the tube to find where the air escaping. However, slow leaks can be a little more difficult to find. In those cases, inflate the tube and submerge it in water and watch for the escaping air bublle.
2. Prepare the tube. Use the tire rasp, to remove the outside coat on the tube. This coating is used in the manufacturing process to keep the tube from sticking to the mold. Unfortunately, this coating will also keep a patch from adhering to the tube. Prepared an area larger than the patch. If your tube has seams that will interfere with gluing the patch to the tube, they can be shaved off with a disposable razor. Note: If your patch aren’t sticking, it is most likely because this coating was not removed.
3. Apply the glue. Apply and work the glue evenly into the surface of the tube. While it may sound counterintuitive, in many cases the glue need to dry (no longer tacky) before applying the patch. So check the instructions for your rubber vulcanizing cement before hand. Here again, the area with glue should be larger than the patch.
4. Apply the patch. Press the patch onto the tube and hold it in place. Use the tire/tube stitcher tool to apply pressure to remove air bubbles under the patch while taking care to ensure the edges are firmly attached as it vulcanizes and cures. Don’t worry about the clear plastic film on the top of the patch, just leave it in place.
5. Check you work. Give the patch time for the vulcanization to cure. Generally, I leave them overnight. Inflate the tube and check for leaks. If it holds air you now have a spare tube.