Unconventional (Free) Sharpening Materials

I admit it, I am an incorrigible scrounge and recycler. I hate waste. I also hate dull tools with an incandescent passion. (What a weirdo. Sighs deeply, looks downward, shakes head.) At some point, these two intersect: here's what I've learned.

1. Old, worn grinding wheels from a bench grinder:

People don't have a clue:  I have been given these, found them at the dump,  pulled them out of the free box at garage sales. As a hand tool, they will literally last you forever, and save your files in the process.

I use the flat side to put a quick-and-dirty edge on shovels, hoes, and "beater" axes and hatchets. The abrasive is hard enough to grind through a hardened (temper burned) layer on many hand tools (like the cheap fibreglass axe you use to chop roots). Not as quick as diamond, but pretty good. Grinds out nicks too. It's also good for rust removal and first-pass edge repair of scavenged tools like hedge trimmers or beater mower blades. Moisture and freeze-thaw does not seem to affect them in the slightest. My nephew broke one in half by accident; what luck -- now I have an extra for another work area.

2. The underside of paving stones:

Yeah, this makes a grinding wheel look positively elegant in comparison, but it's fast and effective. As a material, the bottoms are generally very flat and typically are made of a very dense concrete conglomerate.

Great for shovels that see hard use/abuse. I set the stones on the ground where they can't move and use the full length of handle to grind at a 45-degree angle. The edge doesn't last, of course, but you can refresh it in 10-20 strokes and keep cutting sod/gravel or whatever.

3. Ceramics:

You all know this one. It's the "bottom of a coffee cup trick" for kitchen knives (which is somewhat effective if you still have a bit of an edge left; otherwise you are tilting at windmills, though I admire your optimism). If you see black stuff on the ceramic, you are removing tiny amounts of steel.

Ceramic comes in many levels of coarseness. The coarser the material, the faster it grinds away steel. It also loads up quickly with steel "flour" and ceases to cut unless you scrub/grind away the debris.

Scrap ceramic tile is a a common source, and easy to scrounge. It's everywhere. As well, big-box stores will happily give you a bunch of samples, large and small, for free. Just say you're planning renovations and "the wife" (a phrase I loathe) wants to see how they'll look in the kitchen/bathroom. It gives you an idea of what their actual cost is -- probably  a penny per unit. If you need eco-points, take a cracked/chipped on that will be tossed out anyway.

How do you grind off the glaze? You work it on the underside of a flat paving stone. (This is also a rough-and-ready method to flatten carborundum sharpening stones that have dished out.)

Can you really polish up the blade of hard-used pruning shears with a bit of broken teacup? Yes, if you're patient. Do it outside with a cup of tea, and listen to the birds. It's a lot more satisfying than sitting in a cubicle.

4. Toothpaste:

Toothpaste (especially the nasty paste-type samples you get from the dentist) contains a micro-abrasive. It's brilliant for scrubbing rust spots out of stainless steel knives and sinks. Just put a dab on a cotton rag and polish away.

There you go, full confession. Thoughts? Additions?

Cement. I have sharpened and smoothed more things that I care to admit on cement. You can get a good long stroke on a patio or sidewalk, and a good angle on a curb.

I like the grind wheel idea, I have a pile of them too, I'll dig one out to misuse :D Thank you for that one!

As far as tile, be sure to get a piece of quarry tile, that's my favorite for sharpening with. No glaze to remove, and a nice medium fine grain, not as fine as porcelain wall tile.

Pearl, what exactly is quarry tile? A source of medium grit ceramic would be amazingly useful. You're right, I find that wall tile is rather too fine a grit. I am intrigued.

Quarry tile looks like this:



My dad was a master mason tile setter, I worked with him for a while (I loved it, but I'm just not strong enough to do it all day, it's very heavy work) and we put quarry tile into a lot of restaurant floors etc. It's pretty common floor tile, I saw it listed at Lowes just now when I was looking for a picture. Terracotta is also orange looking, and unglazed, but it's a very soft tile, breaks easily, often hand made or hand made looking, it's not useful for sharpening. Quarry tile is the machine made, harder, more processed version. Terracotta looks like this:

Good info, thanks. I guess I didn't know it was different from other type of floor tile.

Checking the big box websites, it looks pretty expensive. I'll have to ramp up my scrounging skills to get a free sample or broken piece.

Douglas Alpenstock wrote:Good info, thanks. I guess I didn't know it was different from other type of floor tile.

Checking the big box websites, it looks pretty expensive. I'll have to ramp up my scrounging skills to get a free sample or broken piece.

Check restaurant construction sites. It's pretty common in the kitchens. It's really durable and easy to clean. Could find a tile setter, ask him if he has a scrap piece or two, we had a bunch. I wish I could have moved more tile than I did when we came to MO. I had broken quarry tile to make a patio with, that stayed at my house. Broken quarry makes lovely patios.

Hahah, the universe finally coughed up affordable quarry tile! 45 cents each for 6x6 tiles at my local Habitat for Humanity ReStore! They have a roughened top surface; I'll need to rub two together to flatten them for sharpening experiments.

And then, I'll strop the blades using plain old corrugated cardboard. I read about it somewhere -- apparently there's a little bit of clay in cardboard, and it acts as a fine abrasive to polish the edge. I tried it on my Buck knife and it worked!

Douglas Alpenstock wrote:Hahah, the universe finally coughed up affordable quarry tile! 45 cents each for 6x6 tiles at my local Habitat for Humanity ReStore! They have a roughened top surface; I'll need to rub two together to flatten them for sharpening experiments.

Check the back sides, they are often smoother.

Not these ones. The backs have deep grooves.

Douglas Alpenstock wrote:Not these ones. The backs have deep grooves.

Try 90 degrees to the grooves. Most have the grooves, I still use them.
Might depend on what you are sharpening....

That's true. Mostly this will be for rough garden work but I want to mess around and see if they can be adapted for beater kitchen knives. I also have a masonry wheel for my angle grinder if modifications are needed. At 45 cents I can afford to play.

I have to tell somebody...

I swear this is true...

I was clearing some small trees with my lil' Echo saw on Saturday and it was about half dull. Cutting small stuff so I wasn't too worried. Anyways, I hit a sandstone rock basically parallel to the bar and was like, "crap!" as it etched a line across the rock about 5 inches long. I swear to you all that after that the saw started spitting big ol'chips like I just got done filing!

I'll let you all know when I perfect this technique, hahaha.

That's pretty cool. I wouldn't make a habit of it though.

Dan Fish wrote:I have to tell somebody...

I swear this is true...

I was clearing some small trees with my lil' Echo saw on Saturday and it was about half dull. Cutting small stuff so I wasn't too worried. Anyways, I hit a sandstone rock basically parallel to the bar and was like, "crap!" as it etched a line across the rock about 5 inches long. I swear to you all that after that the saw started spitting big ol'chips like I just got done filing!

I'll let you all know when I perfect this technique, hahaha.

Ooooh, Not sure I'm tough enough to sharpen a running chain saw! non running ones, yes but.... ooooh... I won't be trying that technique!

They have a relatively new type of chain that sharpens by pressing it into a jig while running. I don't know anyone that's used one, but if nothing else, they look like they don't have as much usable life as a standard chain. Sharpening the outside of the top plate on a standard chain would eventually thin the plate and change its angle, so I imagine it would eventually ruin its ability to cut, but this could be a very handy thing to remember for emergencies when there is no time for a proper sharpening and ruining a chain would be acceptable.

I've never tried it, but I once heard that the edge of tempered glass (eg a car window rolled partway down) can put a fine edge on a blade.

Just thought I'd toss that one out there.  Seems like it could be a useful factoid when camping or whatnot.

I heard of the "tempered car glass" thing too. I'll try it.

I suspect it is used to strop/realign an existing edge, not sharpen it to create the edge. Usually with stropping, the blade meets the strop with the edge trailing, not leading.

I have tried the glass bit. Honestly, I am not a connoisseur of razor sharp blades, I'd rather have a slight bit of serration so things cut easier. So I could see where if you wanted ultra razor edge it would be great. If my knife is dull, that's not what I need. I did it once. Won't bother again.

My knives are tools. They take a lot of abuse.

Great discussion! I have been thinking along similar lines, as I recently realised quite how horrifically worn my lovely sharpening stones are. I have been struggling to get good edges on them recently, and think this is probably the root of the issue. I need a nice flat surface that I can flatten my stones off against. Something like the underside of a paving slab might be exactly what I need!

Years ago I read a series of books on making your own workshop tools from scratch - starting with a metal working lathe and working up, all using hand tools and casting of aluminium. Very cool books on bootstrapping from nothing.

In them there is a lot of discussion of how to get metal surfaces truly flat. Ideally you use a reference surface, but if you don't have one then you need to use three surfaces and work them against each other. It is possible to get two surfaces precisely dished to match the curvature of each other, but by introducing a third surface you can eliminate that issue and get all three perfectly flat.

You have three near flat surface A, B and C.

Grind A against B until they are level with each other - but each are still potentially dished. Now take A and grind it against C - again, they can end up dished.

Now take B and C and grind them against each other - they are each opposites of A, so cannot have the same curvature as each other. Grind them flat against each other.

Then repeat the process back with A etc... eventually all three will be true flat. Neat process.

He was doing using blue ink and a scraper to lower high spots, but the process amounts to the same thing.

"Not sure I'm tough enough to sharpen a running chain saw!" Hahahaha that made me laugh super hard. I am going to refer to this incident like that from now on. But yeah, I won't be trying it again!

Michael, that is some good info right there. I wonder if that is my my two stones are underwhelming? They sure don't sharpen like they used to. I may get a third and try what you outlined.

I flattened my stones last night.

Used the back of a new large tile, plenty of water. It took about 90 minutes to do all the surfaces of my set of three stones. My coarsest stone was REALLY dished, and took about 30 minutes to do one face. I had the telly on for company.

The action shot shows that two ends of the stone have been flattened already, but the dished out middle portion hasn’t been touched yet. Still plenty of work to do.

All my stones were dished end to end, and side to side. When sharpening my large kitchen knives only a small part of the blade would have been in contact with the stone, at the edges of the surface. I’m keen to resharpen my knives tonight and see what difference it makes.

This was so easy to do, compared to buying sandpaper and gluing it to a reference surface. Thoroughly recommend it.

Horsetail herb is so high in silica that it can be used to polish steel cookware.  The truly frugal could grow their own Brillo pads.  

Sharkskin has been used since antiquity for sandpaper,

What about plain old sand and water as an abrasive?  

I have used aluminum foil and white vinegar to take rust off the rims of my bike.

And I have used shards broken glass to scrape an incredibly smooth finish on hardwood instead of buying sandpaper.

Cool observations! I had not heard of horsetail as a scouring pad, but it makes sense. The world is full of "found" abrasives, provided we have the good sense to see them.

The bar is raised a lot higher, though, when it comes to grinding tempered steel in a precise manner. It is a problem worth solving: the increased efficiency in hand tools ranging from knives and axes to shovels and grub hoes is tangible to the user. And, for me at least, it inclines me to reach for my sharp hand tools instead of electric/gas tools. My sharp tools are ready to go RIGHT NOW. By the time it takes drag out all that other stuff, my sharp tools (and yours) have already finished the task and are well into the next job. My 2c.

Agreed Douglas,

 I am making a Maassi styled hunting knife out of a cheapy internet-bought machetti because I think the design is a good one.   If I could find an old fire axe Id make a dovetail axe from it.    Sharp steel is good stuff.

as a kid I helped chop weeds from cotton they carred an old red brick and a piece of broken ceramic to sharpen hoes in the fields. I continued this practice with our veg garden plus an occasional swipe with a file

What you really mean is concrete.  Cement is only one ingredient in concrete.  Here is a recipe.  
3 parts aggregate like gravel, 2 parts sand, 1 part cement (Portland Cement) and enough water to make is feel like the consistency of peanut butter, pretty much 1 part water.  But the water is the tricky part, you do not want too little (though less is more) and most assuredly you do not want too much as too much water will weaken the concrete. Experience rules. Oh no taste tests to this recipe, wouldn't be good.  

I've had a ceramic rod from a metal halide stadium light bulb for years.
If you get a blade very sharp, then run it over that ceramic rod about 4 times it will shave you.
I like the tile idea, will have to try that for finishing garden tools after all the filing.

K Eilander wrote:I've never tried it, but I once heard that the edge of tempered glass (eg a car window rolled partway down) can put a fine edge on a blade.

I gave this a quick try as a strop, with the sharpened edge trailing the blade, and it does appear to work. It also roughens the glass edge a little, so I won't be using my car window (don't want to chew up the window seal). I am now on the scrounge for a discarded side window from a car -- there are zillions out there somewhere.

I'm not seeing any mention of lubricant in this thread. Dry sharpening is fine on disposable "stones" such as tile and concrete slabs, but fine stones will collect the fine metal bits and become glazed unless they're frequently flushed with thin oil or water. Diamond sharpeners don't seem to become loaded as quickly as others do.

I understand you are talking about single edge tools, but you can sharpen a pair of scissors on a mason jar, any glass container.
Act as if you are cutting a paper cup from top to bottom, basically you will open & close the scissors in the lip of the jar, several times, which will "turn" the edge more then grind it.
Like any edged tool the more you sharpen it, the easier it is to maintain, like pulling weeds every day keeps the garden clean.

Douglas Alpenstock,
Birds of a feather, it was my job to replace the grinding wheel & set all the safety rules, like tool rest Distance, I set  the rest closer than called for, to off set wear.
I replaced good grinding wheel(8") when they wore to six inches, because of tool rest adjustment stopped & left a gap of more than 1/4 & kelp the old wheels.
To get them out of the work place, I got a pass, & they did very well on six inch grinding motors set up, still have some now that I am retired.

If you stress tempered glass just right you will crack it, & that crack will propagate with remarkable speed all across the pane .  Interesting thing to behold.  Try sharpening on someone else's car window maybe.

Justin, wise words. I doubt a light touch on a back window would cause a failure, but then again you don't know where the existing stress fractures are.

I just remembered I have tempered glass salvaged from the doors of a wood fireplace we reworked. I'll give it a go and report back.

I got curious and wondered if I was just parroting "psuedo lore", so I looked it up. Sharkskin was indeed used a sandpaper, has some association with luthiers , was cured with urine and called "Shagreen."  Its supposed to be very tough stuff, far outlasting its modern replacement, sandpaper.

In rural tropical locations, machetes are often sharpened on river rocks. In the places I've been, most village houses have one at their doorstep that has been there longer than anyone can remember. Find one that's the right weight, shape, and texture and you're set for life. They're a little rough at first, but after a few years' use they develop a nice flat surface, just like any manufactured stone.

Pearl Sutton wrote:Cement. I have sharpened and smoothed more things that I care to admit on cement. You can get a good long stroke on a patio or sidewalk, and a good angle on a curb.

I like the grind wheel idea, I have a pile of them too, I'll dig one out to misuse :D Thank you for that one!

As far as tile, be sure to get a piece of quarry tile, that's my favorite for sharpening with. No glaze to remove, and a nice medium fine grain, not as fine as porcelain wall tile.

Sometimes when I'm doing woodwork I'll use the driveway to round over edges.  It's like a huge sheet of 120 grit sand paper.  And, if I'm rounding over the end of a board at least 3 or 4 feet long, I can do it standing up.

 An excellent alternative to using car windows are the internal 'elements' found inside old/broken High Pressure Sodium (hps) lightbulbs such as the one pictured below.

The part you want to use is the white cylinder you can see suspended inside the bulb. That white cylinder is made from 'sintered Aluminum Oxide ceramic' and is pretty tough stuff (harder than all knife steels)  and sealed on both ends with a tungsten wire sticking out.

You can cut then grind or file those tungsten wires off flush to the ceramic to make it more user-friendly. Make sure you wash it well before using, as it's probably covered in heavy metals and toxic gik.

 If you have any friends in the electrical industry or know of any building maintenance personel they can probably get you a broken/old bulb for free (a new bulb work work just fine but not very cost-effective).

 It works excellent for honing just about anything to a razor's edge and one will probably last a lifetime, I've had mine for about 20 years now and it looks the same as when I made it no visible damage yet.

Brian, how would you characterize those bulb ceramic rods? Coarse, medium or fine grit?

I only ask because most commercial ceramic rods are way too fine for what I do.

01 At the  top end sushi restaurants where they serve real Wasabi, the root is grated with sharkskin.

02 Yes, I have encountered all manner of sharpening materials and systems. I get lured into trying these - those I can afford - and the results are mixed. What I find is some materials need to be paired with the blade material for the best results. Overall, diamond works in all cases followed by ceramic. Ceramic gets black with metal and - I usually only use this to sharpen sewing needles and penknives - this can be easily cleaned with an ink rubber. I work with electricity and an ink rubber is great for cleaning contacts. I used to repair computers and sometimes you get  a spoilt card or board with a stamp sized chip that has legs around the periphery. If you cut the legs off, the underside of the chip is a flat ceramic surface.  

03 I use these cheap kitchen choppers for gardening. The metal is akin to spring metal because the knife rings when you strike it. I always desire razor sharpness but I will settle for a bit of serration. Carborundum grindstones just seem to slide off this metal and carbide shavers can't seem to get any grip on the surface. The quick and dirty method here is to use a rat tail file along the edge.

04 Oh, on a final note my pair of Tullen snips has never been sharpened nor has any need of. I haven't the slightest clue what kind of metal it's made of.

Douglas Alpenstock wrote:Brian, how would you characterize those bulb ceramic rods? Coarse, medium or fine grit?

I only ask because most commercial ceramic rods are way too fine for what I do.

Wow great question!

 Well, on THAT scale, hmmm... I would have to rate these things as 'Infantecimal' !!!

Or 'nano-fine'

 I'm almost positive that is a word, although I think this is the first time in my life I get to actually use it haha!

...Smooth as silk!...

But yeah these ceramic tubes are truely the bees knees when it comes to hardness!

....As I was 'grinding' the tungsten filament stubs off
and attempting to put a 'beveled edge' onto the ceramic tube ends with a bench grinder
the filaments AND The ceramic both glowed red hot!!!

  And I would have put a major hurting on that grinding wheel had I not continuously

kept the ceramic cylindrical end in motion, parallel to the grinding FACE of the wheel

( think of this as aiming at the center of the Earth,
  with the 'Earth' being the grinding wheel,
  you'll want to aim the barrel of your ceramic cylinder
  directly at the 'center point of spin' on that wheel! )

...while simultaneously twisting the ceramic rod trying to maintain a constant, steady, 'feed' of the ceramic from left to right across the wheel so you dont dig ruts into your humble, hard working grinding wheel !

 This ceramic stuff is hard to manipulate but with time and patience you will see the results!
Then those beveled edges will be as smooth as silk and you'll have birthed onto this planet a shiny new tool to pass down to others you'd like to see maintain thier sharp edge!

What could be better than that?

I lived off grid in very rural Ecuador for a year, literally "barefoot farming"
Everyone has a machete .. mostly very cheap ones .. which I found to be easily sharpened on most any large semi-smooth stone.
Long before Ecuador, I was a professional cook & owned fine knives & pro whetstones.
There's more than one way to skin a cat ?