Jamie's questions about buffing have stimulated me to brazenly trot out my ignorance and ask a few of my own questions about this vexing technique?
1. What is the purpose of buffing? Not, 'what's the point' with implied derision, but what are people who buff aiming to achieve?
2. What can be realistically achieved with buffing? Can fine scratches be removed? How fine? How about dust motes stuck in the finish? Finish drips?
3. What speed do you use for an 8" buff? A 4" buff? How can you recognize the right speed?
4. How do you tell if you're applying the correct amount of pressure? (I too have seen bare wood show up)
I apologize for including so many questions in one. Experience suggests simpler questions get better responses, but these are all really one problem for me. Thanks for the help.
Good answers so far; I'll probably repeat some of what Odie said. I've been using the Beal system about 6 months and buffed somewhere around 100 bowls. I use a walnut oil finish, and I soak it in over many applications, so I can't speak to harder finishes. If I haven't let the walnut oil sit for a while, some comes out with heat of buffing, leaving a greasy feel to the finish...but that goes away within a couple of days. Better to wait a week or so after the last coat of walnut oil. On to your questions...
1. I started buffing after seeing the rich depth or a fellow turner. It just looks better, very three dimensional. And that is true even without the carnauba. There's a noticeable difference with both the tripoli and white diamond.
2. For hardwoods, I sand to at least 400, softwoods, 800. Fine scratches will still be there, as far as I can tell. Part of reason I like an oil finish over a hard finish, oil hides any scratches, whereas the harder finishes bring 'em out. Fine scratches need removed with the proper grit of sandpaper...I've learned the hard way and had to go back, way too many times! As for finish questions, again, I use walnut oil.
3. As per instructions, 8" @ 1850, 4" @ 3000. I might get a bit faster results at higher speeds with 8", up a little over 2000, but I can't prove it. As already said, pressing hard doesn't really do anything more with buffing, and I don't think longer times accomplish much either. Just a fairly quick pass, overlapping, works best for me. I buff as much as I can with the 8", including what I can of the interior of bowls. As mentioned, the wheels can grab and send a bowl FLYING. Did it once and it flew at least 10 feet. Scary. Start carefully, hold tight, keep your head out of the line of fire.
4. I tried going WAY too hard for WAY too long with the Tripoli just to see what happened. Eventually I started wearing into the summerwood a little. I think it's like anything, practice teaches you. Feels funny at first, and within 10 bowls its habit, and second-nature in 20-50.
I really like the Holdfast buffing adapter. 8" from the headstock is a good distance. Any shorter would crimp my style, at least. I also like threading on, rather than using the morse taper. I'm probably kidding myself, but it feels faster. I don't use the included nylon washer...too easy to leave it on there and then run the risk of an unsecured chuck coming off with a heavy bowl.
One more that thought, already mentioned, but worth echoing. Go VERY light on the Tripoli and white diamond. Just a quick touch per big bowl for me. The carnauba is a bit more forgiving, but you really don't need much. A stick of each will last you many, many bowls.
Final thought: for utility bowls, I don't think buffing really adds much more than initial good looks with walnut oil (again I can't speak for other finishes.) Carnauba protects the bowl, but dulls pretty fast with salads. And there's some discussion on wether or not Tripoli and white diamond would render a salad bowl no longer food grade. Of carnauba IS food grade. All that said, for selling bowls, buffing sure is a quick spruce up for an already pretty good bowl.
Hope that helps!