Articles on Damascus knives, knifemaking, Japanese swords and heat treating of steels

I have tried to keep these articles simple in order not to defeat the purpose of offering useful information to the beginner or layman, but yet enough to help him get the job done right. Much metallurgy has been left out in some areas and may be explained in a more appropriate place or at a later time as I get time or become more learned myself in some areas. I welcome my colleges to pick, tear and criticize because not to correct me on an error would be the worst of sins.

Metallurgy of Knife Steels

By Dr. John Verhoeven

For a more in depth journey into the realm of metallurgy, Dr. John Verhoeven has finally finished his book dedicated to the knife maker industry and he has weeded out the stuff that we as knife makers do not need to make our blades. This is one of the most important attempts by any metallurgist to explain what it is that the knife maker needs to know to get the most out of his craft. John has also been working with me on solving a puzzle about induced imbrittlement of cold rolled and annealed 1095 steel. Although we know the solution to the problem, John nor I have yet to discover the actual cause but given a little time I figure that John should be able to run it down.

Is Damascus steel really stronger?

I get asked this kind of question a lot lately and I also hear things like, Jeez Damascus is a lost art, isn’t it? Or Damascus is sharper than ordinary steel and on and on. Well these are valid questions and can not be answered in a few words like yup sure is or nope it aint.

The problem of a short answer is also due to, what is Damascus steel? Many folks have heard the term Damascus, have heard of Japanese swords and have been subject to some misleading information along the way. I sometimes hear people say things like; Samurai Japanese swords are folded a million times and can cut machinegun barrels. Or how about the story of the blade that cut the anvil in half that made it. Or the Japanese sword that is so sharp that it will cut a leaf in half upon contacting the sword edge as it floats down the creek. And then there is the old falling silk scarf story. Hey Kevin Costner showed us that one in a movie, right.

In a way, I hate to lift the veils of lore and let the bright rays of enlightenment shine in, but some of us are taking these things a little too serious, aren’t we? And yet we can’t help but wonder at times if just maybe there may be a very small glimmer of truth somewhere in one or more of these tails.

In June of 2002 I held a Damascus symposium here at the shop and one of the featured speakers Dr. Sung Beck is a Grandmaster Swordsman. He delighted us with his exquisite collection of Chinese and Japanese swords and also with his finely tuned wit and story telling abilities.

His humorous stories had a point though, pun not intended, and gave us just a little insight as to what it was and is all about. His stories told us how to straighten a bent Japanese sword by banging it over a log or using a monkey wrench and how to pick out a good one for battle; they were truly enlightening and gave us all something to think about. Dr. Beck made many comments from his observations from his past training of cutting numerous things for practice with Chinese and Japanese swords over the years and some of them made perfect sense and others I will have to think about for a spell.

OK, before we get rolling let’s start with just a smattering of background to pave the way. Damascus is a place in Syria and is where westerners first observed the famed swords of the Far East. Actually they were made in India from a steel called wootz and only discovered in the city of Damascus. Wootz steel is melted in small sealed clay crucibles from steel scraps and carbon bearing materials and after solidifying, were then forged at a very low heat into sword blades. Sword remnants tested for content were often found to contain a fair amount of sulfur and phosphorous. It is believed that this made the cast ingots red short, difficult to forge and is very likely the governing secret to the success of Damascus blades. The higher heats that the European smiths were accustomed to, would have crumbled the steel and it also would not have produced the kind of steel that made them famous. Although the task of forging at such a low and narrow band of temperature was difficult, the first side-affect or benefit was tougher and springier steel with superior edge holding properties. The second benefit was the pattern formed by the ghosting of the dendrites which were formed during the slow initial cooling of the ingot. It was discovered recently by Al Pendray and Dr. John Verhoeven that the trace amounts of vanadium were responsible for forming the Damascus patterns because they aligned along the grain boundaries of the dendrites and due to forging at a reduced heat, retained the image throughout the forging process. Although it was the dendrite pattern that gave rise to the Damascening, they soon learned also how to enhance the patterns mechanically.

During this same time frame the Japanese were discovering the methods of producing fine steel blades from iron ore panned from the rivers. This panned ore was smelted in a wood coke furnace and the crude metal was broken up into pieces, forged flat and stacked into billets. These stacks were forge welded together and forged to length. Then it was folded first length wise and after welding and forging again folded sideways and welded again. This process was repeated from 8 to 16 times in order to refine the impurities out of the steel and to remove excess carbon. If you will get out your calculator, you will find that 16 folds will give you 65,536layers of steel if you start with one single layer, if you started with an 8 layer stack, 17 folds will give you 1,048,576 layers. How many layers would you get if you folded the steel one million times? Now this is assuming that you would have the time or, due to material loss from scaling, any thing left to work with.

Now when the sword is forged out of this steel, all of the layers will be lined up and going in the same direction. Any flexing of the blade sideways will be stretching half of these layers and compressing the other half. For sure, this would be as strong and resilient as a modern day forged blade of solid non layered steel. In fact I think that it can be argued that the layered steel would be more resilient because any stress cracking may be stopped as it reaches the next layer. Flexing the sword blade up or down would be the same as any other homogenous blade as each layer is undergoing the same stresses.

Modern day Damascus or Pattern welded steel is manipulated in various ways to produce some very striking looking patterns. Many of these layers will be aligned in such an order as to produce a sound blade, but some of the layers will be running contrary to that which will produce a good blade. In other words some layers will weaken a blade because of an adverse alignment of weld lines. In such a blade, if you flex the blade sideways, the layers do not just stretch or compress, they could pull apart at the welds. A multi bar composite blade or a sanmai blade will have built in factors favorable to the strength of the blade if done in the right way.

A many layered blade will likely have weld lines running across the edge and this will give the edge a micro serration edge. This edge will feel sharper than a homogenous blade and will out cut a conventional blade using a slicing motion. By folding the steel billet like a paper airplane, according to Dr. Beck, the Japanese could improve the swords cutting abilities on the tip’s first couple of inches. This is the working part, the rest of the blade is there to put the first two inches into proper reach. He also suggested that the sword could be made to cut either on a forward slice or on a rearward slice depending on the way the folds were made.

When you boil it all down, cutting is a function of blade geometry, hardness, toughness, sharpness, micro edge serration and technique. Yes Damascus can be stronger, no it sometimes isn’t. Yes Damascus does feel sharper and for many cutting tasks will out perform a conventional blade.

It is interesting to note that Damascus swords and the Samurai swords had a parallel history a world apart from each other and both had an impact on the rest of the world. It is also interesting that both art forms were very nearly lost, indeed, one had to be reinvented. The modern day Damascus or (pattern welded blade) is a blend of both ancient arts and has taken on a life of its own. According to Dr. Verhoeven, pattern welding predates both of these technologies. Check out the Historical Background of Damascus steel by Dr. John Verhoeven

Today’s patterns have transcended those of ancient times, but are they as battle worthy? I believe that many modern day smiths have the capability of producing a blade just as battle worthy as their ancient counterparts and better. And yes there likely are a some blades that although very beautiful will not stand up to battle conditions.

If art is truly, “form follows function”, then where does that leave some of today’s stunning looking blades? I would suggest that the really true art form is in both beauty and functionality.

Author: Lyle Brunckhorst

Prelude to an edge

An excerpt from my book "The Secret World of Sharpening"

Throughout the ages there has been as much mystery and as many fairy tales surrounding knife sharpening as there has been about the mythical swords of lore. This has been due in part because of the age-old family practice and tradition of keeping secret and protecting the processes and procedures in the making of edged weapons and tools. Also, your uncle Al was not about to tell you how easy it was to sharpen his hunting knife, in fear that you wouldn't see him in the same glorious light. It is no wonder that so many folks find it intimidating to sharpen their own cutlery. OK, so there is no real secret on knife sharpening, the process is just clouded up with a lot of misinformation.

The purpose of this booklet is to dispel the myth, to explain and simplify sharpening and to show you how to get an impeccable edge with little effort. But first, let's talk a little about the knife, because it takes a good knife; to first take, and then hold, a good edge.

Hi, I'm Lyle Brunckhorst. I have been making knives since 1976. A few years back, when I lived in Montana, I went under the name of Bronk's Custom knives. Although I grew up on a ranch, the name was the result of my old side kicks shortening my last name, not because I was good at breaking broncos. Nowadays I go under the name of Bronk's Knifeworks. I would like to share with you some of my hard-earned expertise on sharpening the knife and what I have learned about knives in general.

It's hard to imagine civilization without knives. Fact is civilization could not exist, as we know it, without cutting tools. Nearly every aspect of our lives have been provided by, or improved by, something that goes cut. From the veggies you cook in the pan to the clothes on your back, from the house you live in to the car you drive. You know, even the animals in the forest have their own set of cutlery, claws and teeth.

Society however, has yet to design a knife that doesn't need to be re-sharpened from time to time, unless you believe in the ginzu fairy, so sharpening all of these cutting tools is an important enterprise.

It's also important to note that civilization cuts many different kinds of things in many different ways and this leads to many different kinds of cutting tools. A pair of scissors has very little resemblance to a milling machine used to make various metal parts, but they both cut and they both need to be sharp.

When design follows function, as it should, it dictates the shape of the tool and the angle at which it is sharpened. When this basic rule is followed and the craftsman does an exemplary job, the results can be a real work of art. Design can also dictate the material from which the cutter needs to be made of as well. The scissors don't have to be made of high-speed steel, but the end mill does or, it will go dull from heat building up by the friction created while cutting metals with it.

Not every one uses industrial tools, but we all use knives and scissors in our every day life and we can all benefit greatly by keeping them sharp. A sharp knife or scissors is much safer and easier to use and yet so easy to sharpen, that using a dull one is really quite needless and senseless.

Proper knife design is the first issue to consider, as it dictates not only the performance of the knife but also how it is to be sharpened. For instance, a knife designed to chop veggies and slice tomatoes will be quite different from the survival knife intended to chop saplings, split firewood or perform other camp chores.

Knives used for slicing need to be thin in the blade cross section in order to reduce drag and sharpened at a very narrow angle to get a very sharp edge. In contrast, the camp knife needs to be thicker in the cross section for added strength and it is usually sharpened at a steeper angle for a more durable edge.

Choosing the right kind of steel used to make a knife is also very important, as many kinds of steels will not make a satisfactory blade. It is the additives that make the critical difference. Of primary importance is the amount of carbon added to iron to make the steel, with six tenths of one-percent carbon considered minimal for a good knife and .84 % optimal. The carbon does two things: it allows the steel to be hardened during heat treatment in order to support and edge better; and, it forms very hard little iron carbides in the matrix of the steel that is resistant to abrasion (or plainly put, dulling).

The secondary importance is the alloys added to the steel for such things as improved hardenability, stainless qualities and performance. While it is beyond the scope of this booklet to explain all of the important functions of the alloys added to steel, some you may find interesting.

Chromium is added to steel mainly as an agent to make it more hardenable. It is added in much greater amounts, usually with nickel, to make the steel stainless. These can be pluses in the making of a knife, but there is always a trade off. A rustproof knife is nice, but not all stainless steels will make a good knife. The ones that do can be pricey, hard to manufacture into knives, require exacting heat treatment and will never be as resilient as a lower alloy steel. The reason for this is the chromium makes it harden fully whether you want it to or not and it is more prone to being brittle. The past few decades have seen real improvements in using sophisticated steels in the manufacturing of cutlery, mainly due to the influence of the custom knife-maker and the advent of laser cutting technology. Some steels can not be punched out of a sheet or ribbon of steel without fracturing.

There are a number of alloys that form carbides that are even harder than that of iron and carbon, such as chrome, molybdenum, tungsten, vanadium and others. Some of these very same alloys are used to also improve edge retention while at high heat such as high-speed steel lathe tools for cutting metals. Vanadium is the chief alloy, besides carbon, in Carbon-V steel, longtime used by Case cutlery, and should be used in more knife applications in my opinion. Vanadium is used to refine the grain and it also makes the hardest of carbides. Grain refinement is very important as the finer the grain the stronger the steel and the better the dispersion of carbides in the matrix.

I can not over emphasize the importance of proper heat treatment (hardening and tempering) the steel, it is by far the most important aspect of making any cutting instrument. When you alter the amount of carbon or any of the alloying agents, or add new alloying agents, you change the way the steel responds to heat treatment and change the optimum recipe for heat treating the steel. A very good knife can be made from simple plain carbon steel with proper heat treatment. The Japanese sword is a prime testimonial to that. Proper use of alloys can greatly enhance steels in many different ways, but the criteria for heat treating gets more eccentric and exacting as the alloys get more complicated

Proper heat treating while crucial to hardening does several things. It is used to remove the stresses induced during forging and grinding, to refine the grain structure, to soften the steel to make it easier to work, to harden the steel so it will hold an edge and to temper the steel back from full hardness to make it less brittle and to give it resilience.

Heat Treating Simple Carbon Steels

Lets say you have a blade forged or ground out of some simple steel like 1060, 1084 or 5160 and you are ready to make it hard so it will take an edge before the final polishing, handle fitting and sharpening. You now need to heat treat it so that it will be a good blade and perform like a knife supposed to.

It helps to know in what condition the steel was before you started and what you may have done to it in the process of shaping the blade, especially if the steel is not so simple in composition. But we are working with simple so I will try and keep it that way.

Annealing a blade will make it much easier to drill, file, sand and form in the cold state. This process is done by heating the blade to above non magnetic and cooling very slowly. This will result in the carbon disassociating with the iron and other elements and becoming pockets of pure graphite. In turn the iron has no carbides and is very easy to cut. This also produces a very large and weak grain structure.

Normalizing will reduce stresses induced in the steel during grinding or forging and it will also reduce the grain size of the steel. By heating the steel to above the A3 temp and let it transform into austenite, the grains are forced to re-crystallize because the crystalline structure is arranged different atomically for austenite than pearlite or any other form of the steel below the transformation. This re-crystallization starts on the grain boundaries and spreads inward toward the center of the grain. When you allow the steel to cool to below the transformation it happens again and you will get further reduction in grain size. However if the cooling takes place very slowly, as in annealing, the grains will begin to align and cannibalize themselves and grow into larger crystals. Also the grain growth is faster at elevated temperatures, so be careful not to heat much beyond the transformation temperature. Cooling in still air will be sufficient to get good grain reduction. Do this at least three times to ensure good grain structure.

In simple steels with negligible alloying elements such as chromium, re-crystallization takes place very fast upon cooling. Pearlite will start to form long before martensite upon cooling of the austenite. When pearlite begins to form on the grain boundary it spreads across the grain at one half the speed of sound. The trick is to cool the steel from austenization temperature fast enough to lower the temp at which pearlite starts forming to below the temperature at which martensite forms.

For every steel chemical composition, there is a curve that can be plotted to show at what rates of cooling and from what upper temperature to what lower temperature is required in order to induce the formation of martensite. This is called the time temperature chart or graph.

Steels that have no alloying agents require a very fast rate of cooling to prevent the formation of pearlite so that you can obtain martensite.

The temperature at which steels undergo transformation varies with the chemical markup of the different steels. Adding carbon lowers the temperatures at which transformation takes place until about .85 percent carbon. This is referred to as eutectoid steel. At this point the austenization temperature will rise again if the carbon content is increased.

The graph will show that eutectoid steels will harden from 1450 degrees Fahrenheit. In practice this is difficult to do because you have no leeway. A good rule of thumb is to heat the steel to non-magnetic and then add another 50 degrees. This will get the job done with practice if you don't have a way of accurate measuring controls. It can be tricky judging the added 50 degrees. Another way is to get yourself a Temple stick in the proper range and watch for the stick to melt on the steel.

Ok so you have decided to heat the 1060 to 1550 degrees three time for the normalizing and again for the quench. Allow a little time for the steel to get evenly heated through out and for the carbon to go into complete solution. Caution, if you are using fully annealed steel or other wise known as sperodized steel, you may need to add a step prior to normalizing. Check out the following article on grain boundary embrittlement.

When the steel is heated to austenite the extra spacing will allow the small carbon molecule to slip between the iron molecules and when it cools slow enough to form pearlite or ferrite the carbon will escape back out before it is trapped in a vice like grip. It is this condition of carbon entrapment that we get martensite and this condition is under a great deal of strain.

Now that the blade has reached 1550 degrees for a long enough time to be in solution, it needs to be quenched before the grain grows any larger. Note, grain growth is small at this temperature but is present. The target temperature will be about 400 degrees or less in less than 3/4 of a second in time. This means that you have to remove the blade from the heat source and insert into the quench plus the time that it take the quench to get the blade down to 400 degrees.

There are many kinds of quenches that can be used for various steels and the various desirable results and the various sizes of things to be quenched. Knife blades cool fast so are a bit easier to get results. Water would be used on this steel if it were in thick sections but is to severe for thin knife blades unless you are practiced and can stop the process just below the start of martensite formation and before disaster strikes from over stressing the blade. Hot oil is safer for steels in these thin sections. The oil must be hot so that it is very fluid or it will not cool the steel proper. Use a oil with a high flash point if you can to reduce the fire hazard such as hydraulic fluid, heat to above 120 degrees Fahrenheit and suspend the hot blade from a wire and let it go straight down into the oil, bob the knife blade up and down to facilitate cooling. If the blade goes in sideways, one side will cool faster and warp the blade. So remove the blade from the heat, swing it over the oil and plunge it straight down and bob up and down, all in less than three quarters of one second.

As soon as the blade can be handled, clean it and sand a shiny spot on side of blade, check edge with a file to ensure it is hard enough to skate the file and as quick as you can, get it into a tempering oven at 425 degrees Fahrenheit for one hour. Cool the blade to room temperature check the shiny spot for color, it should be a pale straw, and replace back into the oven for a second tempering. If you are have trouble detecting any color on the shiny spot, sand another one next to for a comparison. The second temper is to remove any retained austenite that may have triggered to martensite during the cooling from the first temper.

Wow, you have just done the most important single thing that makes a good blade and now you are now ready to clean it up and stick a handle on it. If you want to check out the true hardness of the finished edge after the tempering, use a trick learned from Wayne Goddard and put a good edge on the blade, then place the side of the edge on something smooth like a brass rod exert enough pressure to flex the edge over a bit and drag the edge over the bar. You should see the edge flex as you move the blade along the bar and spring back again. The edge should spring back to it's original position and not stay bent if to soft or chip if to hard.

Effects of Alloys in Heat Treating Steels

Coming soon:

Hardenability of steels.

Stainless steels.

Carbides and wear resistance.

Sharpness, a factor of carbide size.

Grain Boundary Embrittlement.

Break it and then go fix it.

The Double L story.

Some times when we set out on a new venture, we have little or no idea just where it will eventually lead us and this is exactly what happened here at the Double L, a subsidiary of Bronk’s Knifeworks. The Double L Hoofknife was designed for performance and economy of use by allowing the user to change out the blade as it wears out. This reduces the cost by using the same handle over again and of course a better blade will last longer as well.

I had been working on a research project regarding grain boundary embrittlement of alloy steels in regard to steels such as E52100 and O 1 tool steel. These are steels that I have considered using for some new projects in the future and they require special handling as far as heat treating is concerned. This is the irony, 1095 (the steel used in the “Double L Hoof Knife”) is regarded as non alloy (10XX) steel and should, by its very nature, not have these same characteristics and problems. However fate sometimes does not bend to our beckon and call and reaches out to us with new lessons to be learned.

It should be noted here that the steel mills do not control the individual batches to the nth degree and often trace alloying elements are introduced into the batch from the various sources such as scrape piles of used steel. This will lead to some considerable differences in the steels giving that a small change in the steel chemistry will profoundly affect the steels characteristics.

I dug out the spec sheets of some the shipments of 1095 that I had received over the past couple of years and yes, I did notice that there was indeed a varying trace amount of chromium in some of these batches of steel. Chromium is added to many steels to aid in the hardening process. This is a good thing as a rule and can simplify one of the difficulties of hardening steels, if added in sufficient quantity, but it does require some adjustment to the process because it consequently will also affect the carbon migration. While not enough chromium is present to make the hardening noticeably easier with the 1095 steel, it did prove out in a full days worth of further testing to significantly affect the processes of achieving the optimum desired result required in a first class hoof knife.

A first class hoof knife is one where the edge will last due to its hardness and yet the blade will be strong enough to withstand the rigors of use. It is also worth while to build this knife so that it is economical to use, hence the replaceable blade.

The problem is the time and temperature curve required to disperse the carbon uniformly through out the steel. 10XX steels usually only require a short amount of time to do the job at elevated temperatures but testing here in the shop has demonstrated that trace amounts of chromium can require a much longer soak time at elevated temperatures to get the carbon into full solution and uniformly dispersed from fully annealed steel.

If the carbon is not allowed enough time to go into complete solution, the carbon will form on the grain boundaries as carbides which are very brittle leaving an undesirable grain boundary configuration and brittle blade.

Although this will add a significant amount of time to heat treat blades, it is the only viable solution to achieving truly stunning performance from a blade and it will become standard operating procedures here at the shop. I have destroyed many of the blades in testing and am confident that even though the “Double L Hoofknife” blades are very hard on the cutting edge they are also very resistant to breakage.

Achieving a truly great hoof knife has been a long and arduous task. It has drawn on the experience of the makers 27 plus years in the knife making field, has required much analytical testing, much field testing and last but not least the feedback from our farrier friends and customers who use our knife to make their living.

We have had to replace very few blades and we will continue to do so if any one does have a blade break providing they send it back for analysis. And as always we consider problems here as opportunities to improve what we consider the worlds finest hoof knives. Contact bronks@bronksknifeworks.com

Distributed by Delta Horseshoe Co., 4000 Alvis Court, Rocklin, CA 95677, 1 800 931-7181.

The road to success.

The road to success is very often strewn with the carcasses of failures and projects that ended in disaster. In fact it is usually the expected norm in my shop with new projects and it has become my old ally and friend.

After some 26 years of experimenting with heat-treating techniques, I still get thrown an occasional curve. Sometimes when we feel that we have a handle on things we can get an unexpected surprise.

Some years ago, I was commissioned to grind and heat-treat points for some broad heads and had to case harden the lot. Experimentation proved that I could soak in Kasinite to carborize and quench the points in cold water with no problem. In reality, the points came out of the quench unaffected by the quench to my surprise. The solution was an easy fix however, by placing a screen and air hose in the bottom of the quench tank. The points had huddled together all of the way to the bottom of the quench tank and had used each other to stay warm thereby not becoming hard as planned..

When I started mass-producing hoof-knife blades under the Double L brand, I had trouble doing a differential hardening getting consistent edge hardness with 1095 steel. The airflow was not the answer this time as it cooled the hot oil quench too much and gave an inconsistent depth of hardness up the blade. This time the use of a pump moving the oil laterally across the top of the tank was the answer. Keeping the blade from warping would require the flow to be divided into two separate streams converging on the blade evenly from both sides.

I have been teaching the ABS style of differentially hardening a blade here at the shop for some time and have seen a number of blades pass the journeyman’s type of test often. I prefer the spring back blade as opposed to the edge quench for this test as the edge quench is too soft and allows the blade to bend over the vise jaws in a tight radius. This puts undo stress on the edge leading it to crack during the test. The spring back blade bends over the vise jaws in a wide arc leaving the edge more in tact.

It was no great surprise to me when I decided to try my hand at clay hardening a Damascus blade. Sure I performed the obligatory experiments and all went just as planned, no sweat I said. I was feeling like I had it down, after all, I turned a railroad spike into a tanto that had a nice Hammond and it took a full ninety before snapping. I was full of confidence, I buttered up the blade wired it down and proceeded on to disaster with full colors flying. Sure enough it curved up just like it was supposed to but it also took a dive to the left. No problem I thought, it can be straightened. Then disaster struck as the blade began cracking along its length in several places.

After placing a frantic call to long time friend Michael Bell, I was reassured that I was indeed on the right tract, but just needed to refine my technique just a little. Yea I new the hazards of water quenching high carbon, but I wanted the distinct Hammond line and the satisfaction of knowing that it was a clay hardening.

Michael will tell you that getting into the knife-makers hall of fame is like getting into the philharmonic orchestra, it takes a lot of practice.

My shop is strewn with the carcasses of the past disasters and experiments, but I hear that Michaels pile of rejected swords and knives is awesome, as he does practice his trade very well. I think that you will find that all of the better known and successful makers have had their bone piles as well.

Failure is nothing to worry over, as true success is impossible without it. Indeed I welcome it now as I know that most of what I have learned is the result of it. Good makers like Mastersmith Ed Caffrey join me in the belief that experimentation is the backbone of our industry. If you produce blades without doing it, you’re cheating your self and your customers. Funny thing about a blade is that you can’t tell a bad one until you need it.

The Ginsu Concept

The Ginsu knife has come and gone but the snake oil concept lives on and thrives within the world of infomercials on late night and daytime TV.

I remember well the Ginsu adds, where a pitchman would take a serrated knife cut a shoe in half then dull this knife on a hammer head, proceed to an abrasive brick or some other abrasive board and cut into it with the knife. He would then pick up a ripe tomato and cut it into thin slices. Wow what a knife huh?

After making knives for some years I had the opportunity to watch one of these infomercials and I watched with intent interest because I wanted to know how it was done.

Sure enough the pitchman used the exact same routine and yep it sliced the tomato very nicely.

Now I'm going to try and tell you how you can perform this magical for yourself.

First off the hammer head being flat will only dull the tops of the serrations and second the abrasive soft brick will be cut mainly by the tops of the serrations as well.

Now the real trick is to saw into the brick quickly as you can and then the remainder of your sawing motions are done with side pressure to the blade so as to re-sharpen the edge again.

Simple and easy with a little practice.

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