Update: my bone folder split right down the grain mid-sew
I was flattening a 40-page signature last Tuesday and the folder just cracked apart in my hands, the plastic had gone brittle after 3 years of daily use, so I switched to a cheap metal one from a craft store and it gouged my fingernail on the first pass, anyone else had bone folders that just snap on a random Tuesday?
Plastic folders get brittle from the oils in your hands over time, so three years of daily use is about the max you'll get out of one. Metal ones are too hard and scratch up your paper and nails, so try a real bone folder instead, they flex just enough and last forever if you don't drop them. Teflon folders are another solid pick if you want something that won't leave marks on your work.