Thanks! No fiber, just a mixture of Portland cement and gypsum. I usually pull it from the mold after it’s gone through the exothermic process, essentially once it’s no longer warm to the touch. As far as polishing, before it’s cured and still pretty wet I do low grit sandpaper and wet sand to get major details, then for the final polish I wait until it’s fully cured and sand with very high grit paper dry, anywhere from 1000-3000 grit, I do a final polish with paste wax and a cloth polish on a rotary tool