Originally Posted by
Crankycrank
I have made many attempts over the decades to make patches with old inner tube rubber and the results were iffy at best with too much time spent trying to make them work. Go for some Rema brand patches.
And use the Rema cold-vulcanizing fluid, not rubber cement. As @
FBinNY noted above, an effective patch is a two-part process involving a chemical reaction between the tube, the patch, and the vulcanizing fluid.