My specialty.... So, for most woods, I will turn down to 1/4 inch thick or thin walls. Some woods that are more stable you can leave a bit thicker, but woods that are more crack prone need to be down to 3/16 or so, but I never measure. Generally I have found that woods that have the spring sap running will crack less than late summer or winter harvested trees. This may not be true for some woods, but for Pacific Madrone, my favorite, this is true. I do use a recess on all of my bowls. If you get metal stains, a few drops of concentrated lemon juice, as soon as it comes off the lathe will get rid of the stain in seconds. If you wait a day or two, it can take longer, and it can bleach the wood. You have to take care with tools and hands after sharpening because you have metal dust on them. I wipe both hands and freshly sharpened tools with wet shavings so my bowls don't get metal dust freckles. Make sure to round over your rims. With most woods, I will wrap the rim with stretch film. I don't do this with maple, which has lots of sugar in it, and it will mold under the plastic. I start them drying on the concrete floor where it is cooler. I move them up onto a wire rack after 3 or 4 days. they are dry enough to sand out in a week max, even here in the Pacific North Wet. To mount them for sanding, I have one chuck with those extended finger jaws on them. You have to wiggle the recess around a bit to get all 4 jaws to seat in the recess. I do not tighten up very much, only enough to hold it for sanding. You don't need the grip for sanding that you do for turning. I sand at as slow of a speed as I can, which is max 15 rpm, and slower if you can get it. This way you can keep the abrasives on the bowl as it spins. Impossible to do at 50 rpm. I also made an 'articulated arm for sanding' (there is a video on that), which has become essential for this type of bowl sanding. The articulated arm takes all of the weight of the sander so all you have to do is squeeze the trigger. This makes it possible for the other hand to slowly spin the bowl for sanding. I never bothered with the microwave. It takes too much time and they do dry so quickly. I figure they are dry enough to sand in 3 or 4 days, weather depending. I tried wet sanding a few times, and just found that to be too messy, and not as fast as dry sanding. The only exception here is if I am doing more of a vase form out of wet burl. When that dries, it has a very 3D type of surface, which is essential to the final 'feel' of the form, so I wet sand it to maybe 320, apply some wipe on poly, and let it dry. Then more poly and one of the synthetic steel wool pads on my sander. The more they warp, the better I like them. People love the 'organic' shape of warped bowls. Oh, they never sit flat on a table. Not sure if I would use a tenon. The main problem with using a tenon is that it leaves a much thicker area of wood in the form when drying, and that thickness can add drying stress, and as we all know, drying stress is relieved by cracking...
robo hippy