I have used PB for a few years now, and have had NO ISSUES what so ever. I follow manufactures melting instructions, and use cd 16 or 18 depending on FO. I use color, and go at 1oz/lb for FO. Matter of fact, I have a couple of my first pillars that I made still, and they are still looking like they just came out of the mold. Never had cracking or collapsing or blowouts(even with an 8hr burn). I make 3"x4.5 and 3"x10. Burn times are aprox 60-80 hrs for the small and I quit counting the clock after 140 hrs on the 10".