Theory and practice of "wet" finishig a blade

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lonepine

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May 7, 2010
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J Hoover’s thread claimed he LIKED to hand finish his blades, and also wondered what lube others used for this process. Responses came back as if, yea, EVERYBODY uses a lube to hand finish their blades.

I guess I’ve known about this practice but I don’t know much about it. I though everyone but me did all their finishing with a belt grinder!?! There must be some pretty good benefit from using a lube to put up with the mess that it must make. It suddenly struck me that I am not the all-knowing genius/brainiac/Jedi knight that I thought I was.

What is that benefit of “wet” sanding/finishing?

How do you do it?

How do you deal with the mess it makes?

And the most important question, what the heck is a fishhook?????

- Paul Meske, Wisconsin
 
I'm too damn lazy to write a whole tutorial on hand-sanding :D I think there's one in the stickies thread.

The main benefit of wet sanding is to help prevent the paper getting clogged up with swarf (the tiny bits of metal you're removing as you sand). Similar to using honing fluid when you sharpen.

In the early stages, I scrub back and forth with my paper wrapped around a backer such as a worn file or brass bar. I alternate directions with each grit so I can see if I removed all the previous scratches.

A fishhook is the little swirly scratch you get when you switch directions with the sandpaper. Fishhooks have a nasty habit of appearing about three stages later and being a real bear to get rid of.

Mobil 1 is the best I've found for preventing fishhooks, I think because it does a good job of keeping the swarf in suspension in the oil itself, rather than grinding it back against the blade.

There shouldn't be much mess, it only takes a drop of lube. I wipe off the blade with paper towel when the oil starts to turn black and I feel the paper slippping. Then it's time for new paper and another drop or two of oil.

Once I've worked through my desired grits, I go one step further (higher grit) to ensure a clean even surface. Then step back down one grit and sand dry with fresh brand new paper on each stroke, in one direction only to get the final straight "hand-satin" look.
 
James, said it all except the sandpaper he's using and I now do. It's from Portugal called Rynowet I believe . This works real well for carbon steel and carbon Damascus. I am now trying another product which is I believe works better on stainless steels than the Mobile 1 Frank
 
I keep a little lid or bowl or whatever of water next to my hand sanding knife board, just dip the tips of two fingers in, drop that water on the blade. Sand until the paper quits cutting, or until I need to add just a bit more water. I wipe the blade down with a paper towel now and then to check the finish, alternate direction at least 30 degrees with each grit size, change water every grit for the finer papers, and I keep a little LED flashlight next to the board that I use to check good and hard for stray scratching before moving up to the next grit. Checking all angles of light and view can save you some work later.

I clamp the blade down good and firm, use a pretty solid steel bar to sand with, and often brace my knee under the knife board so I can really bear down on the work. Sanding goes lot quicker that way. I switch to a leather padded file for a paper backer when I'm doing the last strokes of the finish grit. It blends nicely.

For hollow grinds I have a set of steel 12" radius sanding backer and heat-bent plexi-leather backer that I made.

To me, fluid helps the sand paper cut more aggressively and keeps it from clogging early.

It doesn't make a mess to speak of.
 
I use 3M "automotive" wet/dry up through 1000grit, then Norton Black Ice in 1500 and 2000.

Frank Niro said:
I am now trying another product which is I believe works better on stainless steels than the Mobile 1 Frank
Click to expand...

Do tell!
 
Because my brain isn't hard-wired to be a craftsman things that seem obvious to you are not so clear to me sometimes. There seems to be an unwritten rule that for finish sanding blades, the blade is stationary and the sandpaper (wrapped around a firm backing) is moved along the blade. Why not the opposite, a stationary sanding block while you move the knife back and forth across the sanding surface?

Do some/most/all of your knives require hand finishing? I was under the impression that the Pros did all their finishing with the grinder belts. Time is money and a 600 grit belt is quicker than hand finishing. I feel lucky to make a decent grind of the bevels with an 80 grit belt. I try to use finer grit belts but like lightning, they never seem to hit in the same place twice. The speed of the Sears 2x42 doesn't help me except to accelerate the rate at which I make mistakes.

I appreciate the help with this.

- Paul Meske
 
It's just easier to clamp the blade down. Especially when you're changing sandpaper every few minutes.

A 600 grit belt finish will not compare favorably to a 600 grit hand polish. Proper hand-sanding involves alternating direction of attack with every grit, removing every scratch from the previous grit for a very crisp, even surface. Generally, belt finishes all run the same way (perpendicular to the blade) and merely mask previous scratches and flaws. At the right angle you can see the different scratches with the naked eye, under a loupe they will jump out like sore thumbs.

Almost everyone completes their hand-sanding parralel to the length of the blade, it looks nice and "flowy" that way and you can't really get that with a machine finish.

One popular way to get a desent satin machine finish is to use non-woven belts. They're just like the pads you scrubs pots and pans with and give a fairly good looking result.
 
Why not the opposite, a stationary sanding block while you move the knife back and forth across the sanding
Click to expand...
surface?


that is how I do it . I have a 2" x 12" flat piece of corian with leather glued to it and mounted on the bench . I lay a full sheet of paper across it and just move from section to section across the whole 11" of the paper . When that 2" section no longer cuts , I just pull it down to a new section of paper .
 
I use a stationary block with a granite surface and do all the movement with the knife blade. For whatever reason this just works better for me, but unless you use water or oil your paper will load even faster this way.
 
ONeill said:
That is how I do it . I have a 2" x 12" flat piece of corian with leather glued to it and mounted on the bench . I lay a full sheet of paper across it and just move from section to section across the whole 11" of the paper . When that 2" section no longer cuts , I just pull it down to a new section of paper .
Click to expand...

And me too though your sandpaper backing is better than mine, a hunk of 2 x 4 in the vise.

- Paul Meske
 
Justin King said:
I use a stationary block with a granite surface and do all the movement with the knife blade. For whatever reason this just works better for me, but unless you use water or oil your paper will load even faster this way.
Click to expand...

Maybe, just maybe, the paper loads up quicker because it's more effective?

Going the opposite way (stationary knife) would give the benefit of being able to see your work surface as you work on it. I should at least try it that way I guess.

Another thing I've done is to cut a 2 inch wide board to the proper length so that I can slip one of my 2x42 belts over the length of it and use it similar to how I would use a file, except that it's about 20 inches long.

- Paul Meske
 
Mike Barton brought me a couple of sheets of the Rhynowet and he swears that it lasts as long if not longer than Black Ice and it a fair bit cheaper. It is also red as opposed to black and you can use it dry on handle materials. I want to try some more. The Black Ice was a drastic improvement over the standard Klingspor sheets which are not cheap, mind you.
 
lonepine said:
Maybe, just maybe, the paper loads up quicker because it's more effective?


- Paul Meske
Click to expand...

That is possible, although I attribute it mostly to the fact that gravity just carries all of the swarf back onto the surface of the abrasive, where a lot of it will fall free when doing it the other way around. With coarser grits it is really a non-issue since the abrasive is pretty well worn by the time it loads up. With finer grits I just use plenty of water to float it off.
 
I use rhynowet and have not considered trying any other type since I started using it. My sanding fixture is steel with a piece of g10 layed over it. I use a variety of sanding sticks, micarta, wood, steel, some have a piece of 5-6 ounce leather epoxied to them.
 
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