Re: the seal of cotton...
Forgot to add that I also carry a needle and thread to sew, but have never chosen to do so... If I can't get a seal, I mop up the mess inside the tire [carry a plastic grocery sack and paper towels for this], check for thorns, just throw in a tube and utter some expletives. However it is nice to know the needle and thread are an option for one of those
Castaway nightmare experiences. Yep, nice bits of cotton can also be found in the cotton compression bandages everyone has in their first-aid kits...
Re: plugging valve cores
Full disclosure - I hate presta valves. All my mountain bike wheels have Schrader valves. Yep, I drill every single rim and then retape. Schrader, instead of presta valve, costs me about 1 g more weight. I'm a weight weenie, but no lost sleep. Wider area at base of stem will seal and is not a problem with rims wider than about 20mm [inside]. I either use custom turned-down [lathe] aluminum racing wheel valve stems [off a Mazda racing parts web site -?-] or lately, I just make my own from 20" Continental BMX tubes, which are threaded full-length [you want full-length threads to lock down the stem with a nut for tubeless sealing]. How does an entire Schrader tube cost less than one tubeless presta valve? The hole in the rim is larger than a presta, but I can pull out the stem and run either a Schrader or presta tube in a pinch. No more lost pump head adapters causing stress... Pull into a gas station and just add air... Walk over to the compressor in my garage and just fill 'er up... Put a metal valve remover cap on the stem, like the ones you get with a Slime bottle, and you can easily remove the valve core to add more Stan's/sealant
without breaking the bead.
End of presta hatred.
Not yet - forgot my main point - IMHO, Schrader valves do not clog as easily as presta valves.
...maybe even something from the first aid kit... The cores tend to get plugged up so it's nice to be able to replace them when it gets too hard to pump...
Tim