Nothing will give calluses to one's hands as quickly as heavy doses of deadlifts, pullups, or kettlebelling. Basically any of the "pulls" will mess up hands!
The tearing or ripping of these hardened palm calluses are called "rips." Rips have been wrongly embraced by some weightlifting cultures as some "red badge of courage." These folks proudly display photos of bloody palms, covered in now-pink chalk dust, with captions like, "Check out these babies! I worked out hard." The caption should have read, "Look at me. I'm an idiot who didn't take care of my hands. Now I'll have to cut back my training until it heals."
There is no pride in getting a rip. It generally means that one hasn't properly addressed the needs of their hands. (Yes, rips and tears do happen to those who do spend time treating calluses...so don't jump my case.) Let's face it: Rips are injuries. They are cuts or deep scrapes on the gripping side of the human hand. And they affect not only further weight or gymnastics training, they adversely interrupt everyday life!
I bring up this topic because I got a rip the other day while doing pullups. It was after a few days of weighted pullups and kettlebell deadlifts and cleans. I went into this workout looking at my hands thinking, "I should have shaved these calluses off." But for saving the minor inconvenience, I did not. I went straight into the workout even though I knew better. I got the rip, then had to finish my workout hanging from my fingertips.
Treatment of calluses: I've tried a lot of techniques and tools to treat my calluses. I've almost completely abandoned the pocketknife and teeth-gnawing tactics for more effective methods. The above photo is of the Ped Egg. It's like a cheese grater for dead skin. If you watch the commercial, you'll see it's marketed towards a woman's feet...far from a bulky powerlifter! But the Ped Egg works wonders on palm calluses. I tried one at a local gym (eeewww....community egg. Yeah, I know it's disgusting.) Now I have my own.
I also use a pumice stone. For a few dollars, a stone can get some of what the Ped Egg cannot. I use the Ped Egg on the dry, hardened skin before my hands get wet, and the stone while washing my hands or during a shower. This combination ensures I remove whatever I possibly can.
Other options are Dremel tools (I'm serious!) and callus shavers. With my Ped Egg success, I haven't tried either of them. For what it's worth, with the exception of pumice stones, work on calluses when your hands are bone dry!
For when the callus rips: After a rip, it is best to cut away the flap of skin. I've used everything from a thumbnail, to pocketknife, to scissors, to nail clippers, to my teeth. I like to cut the flap when my hands are moist, either from sweat or after washing. The skin cuts cleaner. If you wait until the flap "hardens," you lose that pliability of the skin. Of course washing is critical, and covering during subsequent workouts until it heals is a good plan.
Take care of your hands. There is no elite status for those who bleed during a workout session. Blood on equipment is not only slippery, it's unsanitary and potentially deadly. Rips happen. Let's keep them to a minimum, so we can maximize our training.