HAND RUBBED FINISH
Wet or dry paper in 180 or 220, 280 or 320, 400, and 600 grit. Finer grits may be added later.
Sanding block (home made)
C - Clamp or vise.
Your knife blade arrives from us with a 220 grit, belt ground finish on the major parts and it's probably spotty gray or brown. It may look awful, but that mottled color is the result of a heat treating - freezing technique to make good stainless even better.
First, you have to be able to hold or clamp the blade very firmly for you to be able to keep the flat parts true. If they get "rolled" at the edges, the knife usually appears to be of much poorer quality than when the flat areas are done properly. You may use a vise, or simply C - clamp the handle area to a handy length of 2" x 4" lumber.
Second, make a sanding block from 3/4" to 1" thick wood, using the pattern below. The working, contact area should only be around 3/8" to " inch wide, with the thicker part of the wood used just to make the grip more comfortable. The narrower working surface allows a better concentration of force which will make the abrasive work more efficiently. While the working surface of the sanding black is only about " wide and 4" Long, it's a good idea to put just a little belly or crown into the long dimension of the surface. Just a few thousandths, say 20 or 30, will be plenty.
The crown, or high spot in the center of the working surface of the sanding block, makes it easier to finish the center part of a large flat area and the edge radius fits the inside curve where the bevel of the blade meets the body of the knife. Be sure to use an extra hard wood or even micarta to make the sanding block to prevent getting ripples showing in the finished blade.
Soft pads or fingertips don't work for sanding on hardened steel. The idea is to have the block level things off, not to follow the small irregularities in the metal that are already there.
Knuckle clearance on the sanding block should be enough so that you can run your hand up over the blade without touching the knuckle. Saves skin!
Next, your wet or dry paper should be torn across the short length of the sheet in quarters, for minimum waste, and held on the sanding block as shown in out sketch.
When section A is dull, usually within a dozen firm strokes, move the next section into position at the bottom of the block without tearing off the used area. As sections dull, simply move over to the next fresh area so that only about " at each side of the strip is not used.
Sanding strokes should be in a straight line with firm, two - handed, down pressure. Your "off hand" supplies a lot of extra cutting pressure by riding along with the thumb atop the back of the sanding block. The first blade will take about half an hour per inch, per side, from rough to near mirror finish, full length, both sides. The next grits are faster! When I say you should sand in a straight line, I'm not saying that you have to sand lengthwise along the blade. The idea is to have all the scratches from the size grit you're using at the moment going in the same direction.
Now you can start. Begin with 180 or 220 grit, using just enough water or Cool Tool II to keep the grit clear and cutting. Avoid building up a muddy layer on the blade. Do both sides, top and bottom, with particular care in the area where the bevel joins the body. There always seem to be a few deep scratches left over, coarse grinder marks lurking there. Try to keep your strokes even and parallel. We've found that a diagonal stroke is often the best way to begin with the first grit because you can get plenty of downward pressure and have good control. ( It doesn't much matter which way you run the paper while you're sanding, diagonal, across the blade or lengthwise along the blade. The important part is to get all the marks from one grit going in the same direction so they will be easy to see when you do the next grit in another direction. Grinding marks, going in the other direction, will then be easier to see and eliminate. ) If there is a problem with grinder scratches in the plunge cut, a small, high speed grinder is really handy. They are sold in quite a variety at hobby and tool shops, and can be a great asset if used carefully. Their major problem is that they tend to dig in just a bit, producing an rippled finish.
There is no need to polish the tang of any knife when it is going to be covered with the handle. In fact, polishing the tang will reduce the strength of both the glue joints and solder when you assemble the parts.
Barry Posner has been experimenting with various machinists cutting fluids, and found that a product called COOL TOOL II, mentioned earlier in this section, gives downright remarkable results when hand polishing stainless steel. He uses it instead of water, to float away the rubbing residue and make the abrasive paper grains cut more aggressively. We found that COOL TOOL II will reduce effort and time in hand rubbing by as much as 30 per cent. Results were so impressive that we now stock COOL TOOL II. As we introduced this stuff to the local guys, virtually every one of them came back to thank us, it's that good.
Getting rid of the 220 grinding marks can also be done with a coarse stone, as we mention in detail in another section.
Finding those left over scratches from coarser grits is not so hard if you put a few lines of marker ink along the blade each time you change grits. The marker ink will stay in any old gouges and make them easy to find.
Before switching to the next finer grit, always wipe the blade clean and inspect the surface to be sure there aren't any leftover scratches from the last grit. Any "grinder tracks", which are normally scratches running across at 90 degrees to the edge or back of the blade, show up easily. If you're working with the blade clamped down, put newspaper under it and change the paper with each grit to prevent contamination. Don't be afraid to bear down firmly with both hands. Proceed on through all 4 grits. The first grit is the hardest work and uses the most paper.
Our drawings show specific directions for each grit but that's not important as long as you use each size grit at an angle different than the previous grit. If you are tempted to work all of the grits in a lengthwise motion, don't. You'll always have some deep ones left over that show up at the last polishing and ruin the whole job. You MUST change direction with each new grit.
Check the blade under florescent light. It'll reveal flaws that an ordinary bulb does not. There is a bit of a trick to seeing the actual surface of the steel and not the bright reflections. ( On the other hand, when displaying a knife, by all means, use incandescent light to flatter it.)
The rub with 600 grit is done three times, if 600 is the finest paper you intend to use. First, at a 45 degree angle, then along the length of the blade. Stop at that point, do your guard and grip work, then come back for a third and final 600 grit rub -- BUT -- use oil instead of water this time, rubbing along the length of the blade again. Be sure to run the grit full length with each stroke so you don't get little scuff marks that happen when you reverse direction in the middle of the blade. If you are going to use finer grits than the 600, you need only do the 600 grit rubbing in one direction. The last grit used should be the one run lengthwise, for the most attractive looking finish.
If each progressive grit is done correctly, you'll start to see a mirror effect at the 400 grit, and it'll show very well at the second 600. Yes, that ugly mug staring back at you from the polished steel is really you. If there's the slightest hint of left over scratches from a previous grit at this point, you have to get rid of them or they'll be there to haunt you forever. Once those are out of the way, a light buffing with white or green compound will heighten the luster -- but it is not necessary for a working type knife.
Finishing paper is now available in 1,000, 1,200, 1,500, and 2,000 grit, for a super, hand rubbed surface.
If you're working with a slightly longer blade held in a vise, try to work on to the tip as opposed to having the tip at the end of your stroke, farthest from the body and working off the tip. Most injuries in hand rubbing occur when you run over, and off the point. Your arm is already programmed to make the back stroke, and is going to do just that, even if it means ramming the thumb right into the tip. Having the point towards your body might be a bit unsettling at first, but helps a lot in keeping you from slipping off and collecting a nasty cut. Believe me, they don't have to be sharpened to cut!
Knives with a grind line part way up the blade require a bit more care than the full Vee ground styles. The two flat, parallel surfaces above the Vee grind should be treated as separate areas and sanded with extreme care to prevent the crisp junction of bevel and body from disappearing and the blade getting rounded. This also applies to types with a false edge at the tip. Although relatively small, this area should be kept crisp and well finished, adding a great deal to the quality of your finished blade. If feeling the flat is a problem, making it difficult to keep the sanding block flat on the surface, try working the strokes in a long diagonal. This gives you more surface area to contact and a far better sense of how the block is settled onto the surface of the blade. You should go over the entire blade with one grit at a time. While narrow sections of a blade are harder to keep flat, you'll quickly discover that they also are a lot faster to polish than a much wider section. There's a lot to be said for having a grind line halfway up the blade on a two inch wide bowie.
You'll learn to hate false edges after polishing one. False edges are so narrow that there is virtually no way to keep the sanding block flat on the surface. I beat this problem with a trick that I picked up for polishing those little ridges on the back of a Japanese blade.
With the blade clamped firmly, horizontal and spine up, sand along the length of the false edge with diagonal strokes, moving sideways a bit with each back and forth movement. Watch the scratches left by each stroke to be sure that you are cutting flat on the metal. Now, using the same grit, switch direction of your stroke and go over the length of the false edge again. Each time you get a nice, even set of sanding scratches from one end to the other, switch directions and do it again. This lets you work from a visual reference rather than the tactile feedback that you get from the block moving across the metal.
Blades with fancy choil designs, or filed backs are the most difficult to finish and require more patience. Your rubbing paper must be wrapped around small dowels. or "V" shaped blocks, to get into the filed cuts, and it's usually impossible to rub in different directions. Filed decorations are also somewhat rougher than the rest of the blade, since they're cut by hand and impossible to clean up on the belt grinder. Shaped stones, used in die work, adapt themselves readily to finishing small areas of a knife blade.
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If you do not have a workbench, or want to take your knife polishing project "on the road", you might find that anchoring the blade can be a real problem. My son, Kirk, worked out a handy device that allows you to hold a blade without much regard for where you are. The gadget looks like a rather short, crude canoe paddle. The idea is to sit on the paddle part, and use a C-clamp to hold the blade to the handle part of the shape. The "paddle" doesn't have to be rounded, and could be made is several sizes to accommodate different sized blades, or even chairs.
Most laminated (Damascus) steel is not at its best if polished to a brilliant finish. When you plan on etching to bring up the pattern, very little hand rubbing is needed. Once you have worked out the grinding lines, you are essentially finished. Etching will actually wipe out 220 grit, hand rubbed, scratches.
Many acids may be used to bring up the Damascus pattern, but ferric chloride seems to be about the safest of the lot. It doesn't make your skin smoke, and only has to be rinsed off soon, not "right now". When etching with conventional acids, establish the right depth and then finish (after cleaning and neutralizing ) with diluted phosphoric acid. It will leave a finish similar to the Parkerizing treatment, with its' rust resistant properties.
You might be surprised to find that the acid attacks the hard steel more vigorously than the soft. Use a solution of baking soda in water to kill the acid after you've reached the depth of etching that you were after. At this point, the steel is still extremely susceptible to rust. An oldtrick used by gunsmiths is to warm the steel and melt a little bees way right into the surface. Don't do this if you plan to blue or blacken the steel. Once the steel enchant has been neutralized, a bit of rubbing with crocus or 2,000 grit paper will brighten the softer steel left standing slightly above the harder layers.
This technique does not work with really bold striped bars with a low number of layers, like 30 to 50, especially if they are a type with layers of pure nickel laminated to steel. For those, polish as absolutely high as possible and bring up the color with either gun bluing or black oxide.
Those little, high speed grinders are handy for cleaning up small areas, but don't try to do bigger portions of the blade. They leave dimples and ripples that are hard to get out if the stone or drum isn't worked with precise cuts.
Don't leave the freshly rubbed blade in your vise when interrupted or going off to tackle something else. The metal is so clean from the rubbing process that it will rust very quickly, and that sharp point is dangerous to anyone walking by.
Add some baking soda to your rinse and lubricating water for the rubbing and you'll find that the blades will be far less likely to rust. Even stainless steel will rust very quickly when it is absolutely clean, like it is when being polished.
Camphor of gum, found at any pharmacy, will do a lot to prevent rust in an enclosed space, like a tool box or blade storage container. It comes in a cake. Just cut the glassine envelope that it's wrapped in, and it will be effective for about three months. That's calendar months, not knife makers' months. Knife makers' months are around a year long, like when he says you'll get to your order next month.
Bolsters require a more precise method of hand rubbing to keep the metal flat enough to make the near invisible joint required for a first class knife.
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You'll need a flat plate of something hard, steel, or better yet, a good sized chunk of polished stone. You can find bargains on broken marker stones at almost any stonecutter or try a granite machinists' flat. If you don't get the one accurate to a tenth, they're relatively cheap.
Using rubber cement, glue a whole sheet of waterproof finishing paper to the stone with the abrasive side up. I recommend a grit between 220 and 400. If the stone is larger than the paper, put the paper at a corner. This face-up paper will act as a holder to keep a second, finer sheet of abrasive paper in place on top of it. You may switch the second sheet instantly to suit exactly what is needed.
With the right grit in place, laying atop the glued down sheet, add a bit of water or Cool Tool II and begin rubbing, moving the knife blade back and forth over the paper with a hearty amount of downward pressure. The water will keep the paper cutting just a few strokes longer. The blade will level itself and true up the metal as you rub, without any rocking to round the edges and spoil the bolster joint. This trick is also handy to polish the choil area of hollow ground blades or preparing areas for guards.
HEAVY DUTY SANDING BLOCK
One of our innovative customers came up with a new sanding block. He uses a eighteen inch length of square hardwood about an inch and one quarter thick, and glues his wet and dry paper right around three sides of it with spray glue. The hardwood has a rounded handle at each end. With a hand pushing at each end, you can really bear down on the block to get rid of those stubborn scratches. "Brownells', the firearms wholesaler for gunsmiths, offers a dandy sanding block in their catalog. If using this with a knife blade which already has a sharp edge, be very careful with the length of your stroke.
Below, is a variation which many find useful for sanding areas where a lot of control, two handed, is needed.
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HOLLOW GROUND BLADES
You wouldn't think that it would be practical to hand rub a hollow ground blade, but Clint Breshears does it, and his product indicates that the technique is darned effective.
Clint made a special set of curved sanding blocks, matched to the diameter of the wheels he prefers for hollow grinding. The blocks have about half or a third of circle shaped at the top, and the rest is simply shaped in a convenient way to be clamped into the vise. The wood he used is about an inch and a half thick. He cuts the arc of each just about an eighth of an inch smaller than the actual radius, and covers the surface with one eighth inch rubber, although he says leather might work as well.
When the blade has been polished to thirty micron on the grinder, switch over to the hand rubbing block, placing a strip of the right grit shop roll face up, on the curved and padded surface of the block. Work the blade back and forth, rubbing opposite the grinder marks.
First, any errors in clean up will become apparent with just a few strokes. Swear. Polish them out and rub again. It only takes a short time to get rid of the thirty micron scratches, eliminating all traces of a machine ground finish. From there, go to a finer grit, re polish and then buff.
Having a hollow ground finish without grinder traces in the metal is an exceptional indication of quality, and very effective in making sales.
SUPER SATIN FINISH
After blade, grip, etc. are assembled and polished to the final stage, use 500 grit paper on a sharp edged sanding block to apply the satin finish. You might decide that 500 is a bit too fine and use a grit as low as 320. Experiment.
Each stroke must run the full length and be exactly aligned with previous strokes. Move the 500 grit paper so that you have a fresh spot exposed on the edge of the sanding block for each stroke. Use light pressure and stop when you have an even satin finish. Don't try it on the guard.
If you have trouble keeping the strokes parallel, try clamping some sort of guide alongside the blade so one end of your sanding block can run along it as you work.
A QUICK AND DIRTY FINISH BY BUFFING
A half hour finish can be done by using four wheels in sequence, two for polishing and two for buffing.
The first wheel should be loaded with 220-240 grease less compound, the second 300 plus grease less, the third, black grease stick and the last, green grease stick. The grits may be used on plain hardware store wheels as long as they're well stitched to make the working surface fairly firm.
Grease less compounds harden if not kept sealed. They also smell terrible when they get too warm which spoils the hide glue. They will still work, even when rotten.
Make up grease less compound wheels by simply rubbing the moist compound onto the wheel while it's running. Boy, does it ever fly. It is not particularly easy to wash out of clothing either. Imagine mud made by mixing glue and grit. Smooth it and let it dry for about half an hour. When it's hard, beat the wheel with a small hammer to break up the surface into sort of a crazed pattern. Run the wheel on a piece of scrap steel for a minute to break it in. Grease less compound will actually throw sparks.
Begin cutting on the 240 grit wheel, holding the blade with the cutting edge down and at about a 45 angle so the polishing marks are at a diagonal across the blade. The 240 grit will heat things up quickly and throw sparks as it removes all the belt grinding marks.
Once the finish is even from end to end, move on to the 300 grit using it at a different angle, then use the black and finally the green buffing compound.
The transition from 300 to the black compound will take longest and probably show up some scratches that you'll have to get out before going on. Using the black compound on a stiff wheel, like the sisal or laminated cloth and sisal, will make it cut a lot better.
Final buffing with the green compound is sort of a burnishing process and doesn't take off any material, so ripples or scratches get sort of pushed along without being removed. The grit actually acts like microscopic hammers to flatten the tiny scratches left by the last grit. You cannot remove scratches from 320 or 400 grit paper with green or white compound! ( The exception is with AEBL or 440B. They seem to literally flow when buffed, even after hardening.)
If unexpected grinding marks suddenly pop out during the final buffing, it's an old problem that is caused by the malleability of the steel. What happens is that some coarse scratches literally have metal folded over them by heavy pressures during one of the first finishing stages. You then work over those hidden scratches until they are revealed again in the final stage. Changing your working angle with every pass on the early stages will generally avoid the problem if you also reduce the wheel pressure against the blade.
Change the angle of the blade when going from one grit to the next too. Left over marks are far easier to see if they're about 10 to 15 degrees different that the ones you're putting in.
This finish is fast, and not exactly a custom knife makers delight since it tends to round off the corners and blur the whole design. It does work fairly well with full flat ground blades, but is not recommended with fancier types with grind lines part way up the blade.
Normal safety precautions should be taken when buffing and the blade should be cooled regularly to prevent softening at the cutting edge. Never buff with the cutting edge upwards!
ANOTHER FAST FINISH
Hollow ground blades may be finished to a very nice degree right on the grinder with no hand rubbing. After grinding to the finest "J" weight belt, switch to the micron type belt. This one will wear out in a couple minutes, but it refines the surface about as far as you can go with an abrasive belt. Micron belts will dig in at the plunge cut if you're not careful so kill the very edge of the belt with a sharpening stick.
You should rock the blade just a bit, so the scratch pattern of the belt is at a slightly different angle for each pass. You'll be able to tell how good a pass is by how clearly it cuts.
Finally, switch to a plain cloth belt loaded with the black buffing compound. It will deliver a very fine finish that is very attractive and quite saleable on a working blade. Plain canvas belts are available from Tru-Grit.
If you prefer a matte finish, use Scotchbrite belts after the finest of the J weight belts. These spongy looking belts produce an even and attractive metal surface. Also available from Tru-Grit.
Cork belts will also produce an excellent bright, scratched finish that will stand by itself, or can be buffed to a mirror finish.
A second type of matte finish is done by having the blade glass beaded after grinding to around 320 grit on the machine. Many combat knives use this in conjunction with a patent coating like Kal-Gard, a relative of Teflon, or powder coating. In our local market, we have found powder coating to be much less expensive than some of the other types of 'patent' metal protection.
If there are grinding marks left in the glass beaded finish that you don't like, have your blades blasted with steel shot before the glass bead blast when you do the next batch. For some reason, the steel shot has the ability to mash those grinding marks down flat and invisible. This won't work with 50 grit marks, but does with 220 grit.
Chemical finishing is also possible, after the major grinding tracks are removed. Among the many, are, parkerizing, etching and chemical polishing.
ROUGH AND READY FINISH
It is possible to go from a ground 220 grit finish on a hardened knife, to a smooth beaded finish without any grinding scratches remaining. Have the blade bead finished, but, start with steel shot beading to smooth the surface and then finish with fine glass beading. Grind lines remain very sharp, yet the surface is very smooth and very nice for a utility of military type knife.
GETTING STONED FOR BETTER QUALITY
Cutting or polishing stones can handle a lot of problem jobs in blade finishing. I won't say I discovered it, because using stones to smooth metal dates back a bit farther than I do, and at least one modern maker (Ed Henry ) regularly used stones to refine the metal surface.
First, the coarsest "Carborundum" type stone, made of silicon carbide, can get the grinder marks out of a flat finish, hardened blade faster than rubbing with wet and dry paper and it'll keep the flat parts of a blade a lot closer to a true flat. You'll find them at your local hardware, and they're darn cheap.
Use bench sized stones, that is, about two by eight inches or larger. Small stones rubbed lengthwise can actually cut grooves in the blade and remove far too much material.
For flat finishing, you rub the blade on a firmly anchored stone, not the other way around. Get a new stone and use water or kerosene to keep it from clogging the cutting surface while you work. ( Water smells a lot better than kerosene but won't work if the stone has been pre-oiled at the factory.). Used stones have oil in them already, so you'll have to use kerosene with them. Try to get all the coarse stones' scratches running one way so they'll be easier to see when you go on to the next step.
There is simply no better way to get all of the slight ripples from the grinder and grinding belt scratches out of a large, flat ground blade. The coarse stones are self - leveling and far more aggressive than wet and dry paper when kept well lubricated. Maybe a trifle messy, but it works. After the coarse stone, go on to the medium and fine varieties. The grit varies from brand to brand, but they do about the same work.
Next, finer finishing on flat ground blades can be handled with finer stones. We stock Japanese water stones in 800, 1000, 1200 grits for fast polishing. The stones wear fast and develop a layer of mud as you work. Leave the mud, it cuts faster.
I recommend the Japanese water stones for all tiny knives and particularly for those in or near the miniature class. A 1200 grit finish from a stone is really an attractive satin that can be buffed with very little effort. Grind lines stay much crisper this way! You don't need all of the grits. 800, 1200 and then one of the finest would do the job beautifully. After 1200 grit, buff to a fine finish. Going to a mirror finish on the 6000 or 8000 grit stones is nearly impossible without Japanese polishers' skills.
A little buffing is essential. Even the finest stone, 8,000 grit, leaves some irregularities. What happens is, you polish on a layer of worn stone, loose and floating on top of the solid stone. Each time you press a little differently, you'll break through that layer and rub on the actual surface of the stone. That will make a slight difference in appearance. The finish is still a true 8,000 grit, but the stone leaves a different look to the metal than the mud did.
Finally machinists, Arkansas stone files can be used to shape and finish file work, terminator curves, plunge cuts and folder parts. Most of these have to be used with kerosene, but produce excellent results much faster than with wet and dry paper. A set of Arkansas hard "files" will also do nice job of touch up work on antique, collectors pocket knives.
Do not stone polish an area to be covered by a bolster. Stones will give a smooth finish, but not a particularly consistent or attractive one. You will have to do a final polish of the surface with wet and dry paper or by buffing.
Copyright Bob Engnath 1997