I apologize that I couldn't be arsed to read the whole thread - it may be that someone already advised the following: to avoid leaks during patching, a good vulcanizing is a must. And for a good vulcanizing, the surface must be clean. And that doesn't mean "it looks clean to me". As a matter of fact, I carry a little bottle (really tiny, 2 ml vial) of isopropanol. Ethanol will work just as well. With that isopropanol or ethanol I clean the surface of the tube after the buffing, and then apply the patch. Apply pressure for 30 seconds, and that's it.
Since I've followed this exact procedure from the very beginning of my tube patching days, the number of leaky patches that I've created is close to zero. 1, to be precise - that was on an extremely dirty 12" stroller (pram for you Brits) tire.
Originally Posted by
FBinNY
One of the most important steps is to "stitch" the patch down. You can't do this with gentle finger pressure, you need intense local pressure to work the patch into the tube and make a proper bond. They make
tire stitchers, which are basically wheels on a stick specifically for this job. You don't need to go out and buy one though. Anything that will let you massage the two together will work. I use the rounded end of a 6" adjustable wrench on a table top, using a rocking motion to do the job, you can improvise with anything, but take a minute and stitch the patch down, especially at the edges and you'll have better results.
BTW- if you use patches like Rema, you're also supposed to remove the cellophane on the outside after you've stitched the patch. The cellophane inhibits the curing process (according to Rema) and prevents good bonding.
BTW- there's also a bit of chemistry involved, and there are slightly different formulations of the butyl in tubes. IME- every once in a while you'll run into a mismatch that won't bond no matter how hard you try. In Germany, Rema offers patches of different material and glue for various types of tubes, but only one (the basic butyl) is sold here in the USA