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Question: I wear my climbing shoes in the gym two to three days a week and also outside, and have for several years. The rubber looks good, but I’ve recently started to slip off footholds, particularly on slabs. I keep my shoes in my pack in the car, and they’ve gone through hot and cold days. Can shoe rubber age? Can I sand them down to expose “good rubber”? Or do I need to suck it up and buy a new pair? —Rick Watson
Gear Guru Says: As you’ve observed, dirty or old climbing rubber won’t stick as well as clean or new rubber, with the loss of performance determined by “how dirty” or “how old” the rubber is. I can ballpark the number based on tests I conducted on an adjustable friction board with a slab of granite glued to it. The board measured the maximum angle I was able to stand on with clean vs. dirty rubber—dirty meaning gummed up with chalk, grime, and dust, much as you’d see on your gacky shoes after a weekend sliding off your project. According to the slipboard, the dirty rubber had 10-percent less holding power, e.g., if clean rubber stuck to a 70-degree slab, then the dirty rubber maxed out at 63 degrees. On some routes—most cracks and climbs with large holds spring to mind—the decrease in performance won’t matter much. But on tech faces and polished gym holds, your feet will skip off when they should stick. Dargh, my shoes suck!
In the pre-sticky-rubber days—before 1982 or so—we’d spit-shine our EBs and turn the soles face-up in the sun to warm them before trying tricky, footsy routes, which was basically every route back then since so few climbs ventured beyond vertical. We did this because we thought that clean, warm rubber was stickier. Time has only proven the thesis correct. If anything, keeping your shoes clean today is more mission-critical than ever because modern sticky rubbers pick up more dirt and chalk than the hard soles of yore—back when you could count all the 5.12s on your fingers and toes.
I didn’t test whether old rubber is less sticky than new, but I can affirm, based on anecdotal evidence, that it is. Rubber, natural and synthetic, oxidizes, or hardens, with age, not unlike our own mortal containers. And when it hardens, it becomes less sticky. Climbing rubber also polishes with use and feels slippery, particularly so when you climb indoors, on holds that buff the rubber rather than grind it down like rock. (If you have a pair of dedicated gym shoes, you’ll notice how much shinier the toe zone is than on your outdoor pair.)
Storing your shoes, dog, or baby in the car generally isn’t a good idea, either. On a hot day in Texas, the inside of a sealed auto parked in the sun can soar to 150° F and beyond. Rubber will survive the heat, but the glue that holds it to the shoe is heat sensitive—your sole could delaminate.
OK, so your shoes don’t grip so great anymore. Don’t panic—the three tips at right will get them minty fresh, gripping like new.
REVITALIZE YOUR ROCK SHOE RUBBER
1. Wire-brush or swipe polished soles with coarse-grit sandpaper to expose fresh meat. Notice how the soles on new shoes aren’t smooth but instead have a brushed texture—aim for this. If your shoes are simply dirty, skip this step.
2. Wash the rubber. Plain water and a nylon (or wire) scrub brush will do the trick. At the crag, you achieve about the same thing by spitting on your hand and rubbing the soles until they squeak. Gross but effective.
3. Skip step 2 and get a store-bought rubber cleaner and revitalizer like Shoe Spray ($20) from Tension Climbing. This elixir will clean rubber until it feels spanking new. You can also use alcohol or a “tape-prep” spray like Mueller Pre-Tape, which you might have in your tape kit. Alcohol will effectively wash the rubber especially if you scour it with a toothbrush. Muller spray has alcohol, plus harsh chemicals. Use sparingly.