Several years ago I worked with my good friend and camping partner Phil Brennion, professional woodturner from Chino Valley, Arizona, to write an article on his method for turning translucent ponderosa pine vessels. Phil, a true turning perfectionist and demonstrator, has this infectious ability to get you to try new turning techniques and finishes.
This past summer, a 20’-high, 6’-diameter white pine in our back yard evidentially decided it had endured enough Iowa winters and shed its needles. When cutting the tree down and removing the limbs for the burn pile, I decided to save a few sections from the trunk for practice pieces for my son at the lathe. Little did I know at the time, but I’d be the one learning from these scraps and Phil’s advice. After mounting a piece about 12” long between centers and letting my son Carter practice his gouge techniques, I told him the next night we’d screw a section to a faceplate and let him turn a few small end-grain bowls. After screwing a piece about 6” long in place, it hit me this was the perfect opportunity to try a translucent. Since it was scrap wood anyway, there was nothing to lose but a little time. Shown below is the process I used.
With tailstock supporting the stock, turn the trunk section round, removing the bark as shown below. Consider hanging a piece of plastic behind the lathe to catch any moisture.
Slide the tailstock out of the way and rough-out the inside using a small sharp gouge. Since my stock was only about 5” in diameter, I started with a ¼” gouge for the rough cuts as shown below.
Next, as shown below, I turned the outside to shape for a wall thickness of about ¼”.
With the piece turned to rough shape, I rotated back and forth between the inside and outside of the vessel using the 1/4” gouge to finalize the shape, bringing the wall thickness down to about 1/8″. To ensure even wall thickness I gauged the thickness between my thumb and middle finger as shown below. 
In addition, I moved the halogen light I use when turning next to the vessel to see if the light shining through the vessel wall was even. It’s easy to get the wall thickness near the top edge thinner than that at the bottom. Light gouge cuts near the base evened out the wall thickness. At this point the vessel is so thin and soft you can actually squeeze the top, opposite edges of the rim and slightly distort it. When turning the vessel to final shape, it is important not to get a knife edge as the top edge. Consistent wall thickness is the goal.
Then, I sanded the piece running through 100-, 120-, 150-, and 220-grit sandpaper. Not only does sanding smooth the interior and exterior surfaces, but by applying just enough pressure, you can heat the piece and drive any moisture from the vessel. The vessel walls must be extremely thin for this to work. Measuring the wall thickness with a digital caliper, the thickness measured 9/128″.
Although the vessel was translucent at this point.I decided to push my luck and make two more cuts on the already sanded inside surface. The vessel was so soft at this point it actually distored slightly from the pressure of the gouge against the inside wall. But, with two more light cuts and additional sanding, I was able to bring the wall thickness down to 5/128″ (measured with a digital caliper). Also notice the top edge of the vessel is not flat, but slightly wavy. I believe this happens for two reasons. First, when sanding the top edge, even the slightlest amount of pressure distorts the rim. And secondly, the softer wood probably sands more than the harder wood. Frankly, I like the contoured top edge.
Finally, I applied two coats of Minwax Antique Oil Finish.