BUFFING the wood and the finish
Page 1 of 2, General Information
How It Works
An abrasive stick is held against a spinning cloth wheel until the cloth is "loaded" with the abrasive. Then the wood is held against the wheel so the abrasive can do its thing. The devil is always in the details, and a lot of woodturners have problems with those details.
The "system" that has become the accepted technique among woodturners is to buff with Tripoli and White Diamond, followed by an application and buffing with Carnauba wax. Tripoli is Jewelers Rouge that is about 900 grit in a comparison with sandpaper grits. White Diamond is a Tin Oxide that is about the same as 1500-1800 grit sandpaper.
There is always a question about how a 900-grit Jewelers Rouge can give a polished gloss, while a 900-grit sandpaper will leave a rougher looking matte surface. The answer is simple, it's all about the shape of the scratches.
Garnet, wet/dry, or Micro-Mesh abrasive particles have a more rounded shape, and they will leave a "U" shaped scratch pattern with sharp points between the individual scratches. .
Light will reflect from the bottoms of the grooves, and the surface will have more gloss that that left by the sharper Al-Oxide poarticles of the same size.
The 5 Rules of Buffing
Just as there are "5 Rules for sanding", there are some rules for buffing that will keep us out of trouble and help us develop a better technique.
Buffing is not a substitute for sanding.
It will not remove tool marks, torn grain, sanding scratches, or a rough wood surface. If anything, it will polish the wood surrounding the surface irregularities, and make them all the more obvious.
Always hold the work against the wheel in the trailing position and below the horizontal center of the wheel.
That means the wheel will be trying to throw the work away from its surface, and not pull it into the surface. If you can't tell which is which, rotate the work forward while the whell is not spinning. If it goes into the wheel, you are holding it wrong. If it rotates away from the wheel, or does neither, you are holding it right.
Less abrasive compouind and wax is better.
ALL woodturners use too much buffing compound or wax. If it feels sticky, you have used too much. Holding the stick against the spinning wheel for 1- second, and NO MORE THAN 2 seconds, will be enough to load the wheel. More than that and all the wheel will do is smear the compound around on the surface, rather than polishing it.
Less speed is better.
The faster the buffing wheel spins, the harder it becomes, and the faster it polishes the surface. Also, the faster the wheel, the more likely it will try to grab the work out of our hands.
900 - 1200 RPM is a good speed for an 8" buffing wheel.
Faster than that, and there is a risk of damaging the surface. Slower is just that - too slow. The only way most of us can get 1200 RPM is to spin the buffing wheels with the lathe.
Always remove any residue before using the next buffing wheel.
I know the instructions don't say to do this, and many woodturners don't. The problem is that the previous coarser compound will always compromise the present grit, it will eventually contaminate the other buffing wheels. We don't really want Tripoli in the White Diamond wheel, or White Diamond abrasive in the wax.
A buffed Aluminum-Oxide scratch pattern will have a higher gloss because of the new reflective surfaces that were created.
Light from these flat surface is reflected with little scattering. Light striking the grooves is scattered as before.
The effect is a higher gloss,
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