Elky, Bite it and if it feels hard I keep it, also good ones will make a pleasant tone when dropped on a wood surface flat side down, If it "poofs" or " accordions" while cutting, ditch it immediately. After that install on low speed then I drop the shaft tip side down about 50-100 times on its face and edges against concrete garage floor, put back on lathe and shape... Call it a day. Id say I'm having great luck with a good ol Elky for now on. also to avoid bad fraying I shape the top with 220, 400, 800, 1,000. They hold chalk extremely well, granted I use Taom V10. I have had zero glazing problems, mushrooming or miscues, this is surprising.