Dissertation on finishing materials , etc. [long]
RonZ
>This is posted in response to Doug Trembath below and possibly others might benifit from it or would like to comment.
I don't think you'll get an actual grit rating on 0000 steel wool or buffing compounds as their composition is not like abrasive paper
Sandpaper:
It leaves scratches hence stopping at 400 and using material that will leave less such as 0000 steel wool or 3M synthetic equivalent for example. The random placement of the abrasive such as 0000 steel wool or tripoli on a buffing wheel randomly leave striations that are less noticeable than abrasive paper striations as applied on the lathe, unidirectional.
Even finishing up to 12000 via micro-mesh will leave scratches but they are undecernable by the naked eye.
Myland�s Sanding sealer
Here you want to stop at 400 because any further sanding with higher grits will close the woods pores and not allow the finish to meld with the wood. This is the key phrase here, you're now making the finish and wood one. Additional applications of sanding sealer will then build on top of that as will the finish of your choice. I usually apply two coats. I will add here that I would use Myland�s melamine finish instead of continuing using the sanding sealer as Mike did, even though the properties are similar. I usually apply 2-3 coats of the melamine to make sure I have a tough finish before heading for the buffing wheel. I will also not use carnauba stick as I don't know how well it will meld with the melamine. I will use carnauba/bee paste wax [Myland's or equivalent] as it is tolulyne based and the thinner will assist in partial melding.
Steel wool - 0000
I first heard this rated at around 600 by Alan Holtham a professional turner in the UK. I then heard it from many other word of mouth sources. You can establish the correlation between 0000 steel wool and tripoli by taking a hand rubbed shellac finish, for example, that has been done the same way since the early 1800s and the introduction as shellac as a finish. Almost all professionals recommend 0000 after 400 grit hence being the next grade in grit ~600. The next step to obtain a higher gloss is to use rottenstone, the component used in Tripoli.
You can read Jeff Jewitt�s article on padding shellac here:
http://www.assoc-restorers.com/r-articles/padding_shellac.html
Buffing
As far as buffing numbers you must be thinking rouges instead of the tripoli and white diamond compounds. 20,000 grit is about one micron, not really applicable for woodworking.
They are usually rated as follows:
Tripoli is listed as a cutting compound, has the active ingredient rottenstone and is recommended for mild cutting action for copper, brass, and aluminum. This is good for the removal of lines left from the application of your finish.
White diamond has the active ingredient of tin oxide and is listed as an intermediate compound between cutting and polishing. It may be used for plastics and will cut and gloss in one operation. This is good for taking your project from the tripoli stage to a gloss finish.
Some have rated Tripoli at 1200 and white diamond at 2000 so to be safe one can give a range of 800-1200 for Tripoli and 1200-2000 for white diamond. Either way the sequence remains the same.
Additional References:
http://www.sydneywoodturners.com.au/site/articles/finishing/buffing.html
http://www.dicoproducts.com/buff_instructs.html#Definitions
http://www.ganoksin.com/borisat/nenam/buffing-material.htm
http://www.homesteadfinishing.com/htdocs/rubbingout.htm
Thanks for looking and I'm always open to suggestions and corrections.
