Just4Fun":3kfw2q0s said:
Can I follow up the issue of how polished relates to sharp? Specifically, does a more polished result indicate a sharper chisel?
The reason I ask is that I have tried a 3000/8000 Bearmoo sharpening stone the same as shown above, with disappointing results. I usually sharpen with wet & dry (because it is what I have, so let's not get into a debate about that) finishing on a leather strop with Autosol. The result is a polished chisel that is pretty sharp. I tried the stone to see if I could get a better result. The chisel was noticably more dull after the 8000 stone than after 2000 or 3000 wet & dry, and didn't improve much when I stropped it. It didn't feel any better in use than when I use wet & dry, and I have abandoned the stone because of this.
Perhaps 'scratch-free' or 'much smaller scratch pattern' might be a more accurate term than 'polished'; 'smooth' rather than 'shiny'; I think the word is used as a sort of shorthand.
For a really good cutting edge, you want two faces meeting at a line (the edge itsef) both faces being as free of blemishes and scratches as you can achieve. If the back of a chisel or plane iron were left with the manufacturer's grinding marks, and the bevel made as smooth as possible, the result would be a ragged edge. Similarly, if the tool were just rough honed, the edge would still be ragged, to a degree. In that state, it could well be sharp enough for rough work like heavy chiselling with a big mallet, or rough jack planing, but for finer work, something better is desirable. Hence 'polishing' out the scratch pattern from the honing stone (which does the bulk of the metal removal to re-establish the cutting edge shape and geometry during a honing session) to smooth the cutting edge. Only the very edge needs 'polishing' in this way, on both the bevel and the back, just to get as near to smoothness right at the edge as you need.
I'm not suggesting that this is the 'right' way, but what works for me is as follows. Once a bevel is established by grinding, I hone the edge on a fine India oilstone until I can feel a burr right across the back at the edge, but don't 'back off'. Then transfer to a Welsh slate stone, and holding the tool a degree or so higher than I did on the India, draw the edge back several times, lifting off on the forward stroke. That polishes the very edge on the bevel side. Then flip the tool over, place it dead flat on the slate, and draw back, repeating two or three times, with just a little finger pressure at the cutting edge end. Sometimes, I need to flip from bevel to back three or four times to break off the wire edge. That gives me edges that are shaped on the India, and refined right AT the edge on both bevel and back on the slate, without need for stropping. I can then repeat the hone-and -polish sequence several times before needing a touch on the grinder.
The same principle will work with just about any sharpening medium - a very fine wet-and-dry will substitute for a slate stone, and whatever you have that works for the India.
Sometimes there's a bit of suck-it-and-see with sharpening media. You may need to fiddle about to find a particular combination of abrasives and minor modifications of technique until you get something that works consistently for you, but the basic idea is gross removal of metal by grinding the whole bevel, then establishing an edge by honing metal away, then polishing just the very edge for maximum sharpness.
It might be worth trying the 'draw back with a little pressure, lift off to return' trick with the 8000 stone, holding the tool at a slightly higher angle than on the coarser stones. It may work, it may not; but nothing lost for the sake of a bit of experimentation.