What Kind of Sandpaper Abrasive do I use to Sharpen Blades?

Sandpaper Materials

Did you know that sandpaper is considered a cutting tool? Much like saws, sandpaper is purpose made for the material they are going to be cutting. While you could, you probably will not choose to use a metal saw to cut wood. You definitely would not use a wood saw to cut steel. Sandpaper comes in many “Grits” (basically the number of cutting edges in a given area) and working the appropriate grit to sharpen chisels is important, this article is not about what grit to use to sharpen your chisels. I looked into what is the best sandpaper abrasive material to use for sharpening my chisels and plane irons and this is what I have found.

1. Aluminum Oxide is the better choice for the more aggressive passes and to clean up damaged blades. Grits from 80 – 320
2. Silicon Carbide is the better choice for the final passes where the blade edge is being refined. Grits from 600 to 1200
3. Above 1200 grit (or 15 microns), are the lapping films. Lapping films are offered in both Aluminum Oxide and Silicon Carbide but are processed beyond the standard sandpaper grades.

When it comes to durability and strength to sharpen wood chisels or plane irons, Aluminum Oxide and Silicon Carbide are the better sandpaper abrasives for sharpening. They are often used interchangeably. Both are affordable and easily found in stores and on-line. Often Aluminum Oxide and Silicon Carbide are combined together or with other abrasives.

Still, this answer has many variables but what I looked at was simply the best sandpaper abrasive material to use to sharpen blades. Specifically, the hardness and durability of the material. I found that most manufacturers I found at the hardware store did not list their abrasive blend on their packages leaving the buyer to make a guess. Most commercial sandpaper manufacturers will blend several abrasives to come up with what they think is the best cutting solution.

This leads me to state that the best source of sandpaper used for your sharpening system will be from a specialty shop. This paper will cost a little more but will be used exclusively for your sharpening requirements. That way, each sheet will last a very long time – much longer than the sandpaper you use on wood.

While this article is about the abrasive material used in sandpaper, it is important to note that the backing and adhesive also matter when choosing sandpaper to sharpen a blade. This is because it is important to use plenty of cutting fluid – just water or maybe light oil – to flush away debris during sharpening. The backing and adhesive will have to stand up to the fluid used.

I am not a materials expert but here is a table of what I have learned while searching for my own sharpening system.

Common Materials used for Sandpaper Abrasive

Abrasive	Benefit
Aluminum Oxide	Tough and fracture-resistant, this abrasive can be used on most materials. Most suppliers recommend Aluminum Oxide for the heavy reconditioning passes.
Silicon Carbide	Silicon Carbide has a resilient structure that will break away with use, providing new sharp cutting surfaces. Most suppliers recommend silicon carbide for the polishing passes when used for sharpening. Silicon Carbide is what is used to produce what is commonly known as Wet/Dry sandpaper.
Zirconia Alumina	Zirconia Alumina sands faster and lasts longer than Aluminum Oxide, and can also be used on most materials. However, it comes at a cost. Most common (if not exclusively) sold as belts, this material will transfer heat rapidly and is commonly used for aggressive material removal.
Nylon Mesh	The most cushioned substrate gives you control over the finish on softer surfaces like wood. Resists clogging. Because this is a mesh, it is not recommended for sharpening.
Garnet	This naturally occurring material is very soft compared to the other abrasives. This is the reddish-orange color sandpaper commonly found at the hardware store. While it can be used in a pinch to sharpen blades, it will not last long and will not produce an ideal edge.

I Did a Little Test for Myself

I have been looking for a sharpening system that I would actually use for a long time. I own a couple of diamond impregnated steel plates that I had been very satisfied with. However, they cost over $100 US for each plate, and to have the complete set I felt I needed, I was still looking at a couple of hundred dollars more.

I recently came across a sharpening system sold by Taylor Tools that was very affordable and I was so happy with the system that I found myself sharpening ALL to my tools to a mirror finish on both sides.

For this article, I wanted to do a side by side comparison of the Taylor Tools system 3M™ micro finishing lapping film and regular Wet/Dry sandpaper. Knowing that the typical “Wet/Dry” sandpaper I can pick up at the hardware store (or any automotive store) is made with silicon carbide, I chose to use that for my alternative sharpening sandpaper.

I found some cheap chisels that I had not sharpened since inheriting them many years ago. I believe they are made with cheap soft steel and probably would not hold an edge anyway. I used my most aggressive diamond stone to bring them to an equal starting place and to square up the bevel. I had to take a lot of material off to get them even close to a bevel that might be considered good – if you didn’t look very close.

Preparing the blades took me well over 45 minutes. These chisels were not taken care of previously and were in pretty rough shape. Even with the diamond plate, getting them ready was time-consuming. The rest of the test went very quickly. This is just a testament to keeping your blades square and sharp. A little maintenance after each use will go a long way to keeping your blades in good condition. And don’t use them as glue scrapers.

Now that the blades were prepared and looking somewhat equal, I tried to match the grit steps between the sandpaper samples I was using. I was able to find the Wet/Dry sandpaper in 400 grit, 1000 grit, 2000 grit, and 3000 grit.

The closest match for each grit from my existing Scary Sharp system was 200 grit, 1200 grit, 1800 grit, and 8000 grit. This was not a close match but it was the best I could do at the time. I tried to take pictures of each step but the slight differences were not picked up by the camera so you just have to read about it!. ????

For each subsequent step, I took exactly 20 strokes (pull stroke only. Push strokes will bite into the sandpaper and make your day very sad). No more than 20 seconds were needed for each step. Not counting messing with the camera and using the spray adhesive to hold the Wet/Dry sandpaper to the flat plate.

While the camera did not capture the changes in the surface finish, my eye certainly could. The first step – 400 Wet/Dry vs 200 3M™ micro finishing lapping film was a dead heat. There was not much difference between the results. Both took down the rough surface left by the diamond plate equally.

The second pass is where I started to see a difference. This was the Wet/Dry 1000 grit vs 3M 1200 grit. I could clearly see the beginning of the mirror finish at the end of this heat on blade #1 using the 3M sheet. The Wet/Dry sandpaper took down the roughness significantly but I could detect no mirror finish.

The final 2 rounds ended in a tie. both were able to produce significant mirror finishes. Probably, for most uses of these chisels, this finish would be good enough but they were not the best finish that could have been produced.

I proceeded with the remaining Scary Sharp System grits and produced an excellent mirror finish on the bevel of the chisel. for a final touch, I ran the bevel over a leather strop to clean up any burrs that remained on the blade. (The soft steel left a lot of material just dangling off of the sharpened edge. The leather removed that quickly).

My Recommendation

Well, I went through all of this to decide which material was best to sharpen my tools. There are many articles available to tell us HOW to sharpen tools but I still wondered what abrasive material I should choose to do that sharpening with.

I was surprised that the common Wet/Dry sandpaper did so well. There are a few points that I observed during my test.

1. The plate the sandpaper is affixed to has to be dead flat or irregularities could be introduced in the blade. By adding spray adhesive to the plate, the flatness might be compromised over time.
2. Unless you have a dead flat plate dedicated to each grit you use, peeling the paper between grits might prove to just add time to the process.
3. If you need a quick solution to your sharpening needs, the Wet/Dry sandpaper you can find at local retailers will go just fine.
4. If you go with Wet/Dry sandpaper, you will have to come up with a flat surface to mount the paper on. I recommend NOT using your table saw. The water will rust it.
5. If you want to go the extra mile in sharpening your tools, the investment in lapping films with PSA (Pressure Sensitive Adhesive) and dead flat glass is well worth the cost.

I could not compare the long term cost of the 2 methods directly but to me, the Wet/Dry sandpaper would be slightly more expensive in the long run. Plus, what I could buy at the hardware store did not have a pressure-sensitive adhesive backing. I can not tell at this point which sandpaper would last longer though, both held up well during this short test. Over time, the Wet/Dry sandpaper may wear out or become undesirable because of the adhesive buildup.

For an overall, complete system, I feel that the Taylor Tools Scary Sharp system is the winner. For my needs, it is just a complete system that came with 3 dead flat pieces of 5/16 inch (‪7.9mm) thick float glass and grits from 0.3, 1, 3, 5, 12, 30, and 40 microns (60,000; 14,000; 8,000; 1,800; 1,200; 600; and 300 grit). The finer graduations mean less time on each step. Finally, the sandpaper has a pressure-sensitive adhesive backing so each grit size adheres to the float glass and no time is spent with spray adhesive or cutting the sandpaper to size.

https://www.woodworkingshop.com/ also has a sharpening kit using sandpaper but the flat plate was out of stock. I have ordered some of their PSA abrasive paper and will follow up with a comparison. This site also sells PSA sandpaper in rolls. A quick look seemed like the rolls were cheaper then the equivalent amount of sheets.