Updated: Apr 21, 2021
As woodworkers we are usually pretty good at assessing if a new tool is going to suit our needs and represent good value. We read reviews, compare prices, gauge quality and then try to match that information up to our budgets to get the right tool for the job. In this, we are usually united. The choice of the most crucial part of the tool however, the bit doing the work, often divides us into two camps. Those who buy the cheapest bits, blades and discs they can find and replace as needed, and those who buy the most expensive kit with hopes of better performance, longer life and the increased anxiety of inevitably hitting a nail and destroying your favourite cutter.
Then we have sandpaper. Perhaps the most used and least cared about cutting tool in the shed. We will hum and harr over the best blade for a saw or the wisdom of spending the extra on a carbide cutters over HSS, and then come to the sandpaper section of the big box store and look no further than “120 grit, that’ll do.” We save old sanding discs long past their usefulness and stuff them in a drawer, occasionally flipping through caressing the surfaces gently to see if they are ‘still good’ for another session until they disintegrate and we finally break out a ‘freshy’. We do this because ultimately we know that sanding can be an expensive exercise.
A few years ago this time honoured ritual was further interrupted by the advent of “The Sanding Net”. These mesh-like structures promised longer life, faster cutting, better dust extraction and greater value for money, but also often came with a much higher price tag per disc. I must admit in my first trial with them I was impressed with the performance, but the longevity didn’t seem to be even close to the claims on the label. So as a scientist in my day job and a tightar… value conscious consumer at heart, I decided to design a few tests, buy a whole bunch of different brands and types of sandpaper, and put them through their paces to work out which would provide the best balance of performance, durability and value for the Fixit Fingers workshop.
In my hobbyist setup the primary sanding device is an 18V cordless 125mm random orbital sander. Specifically, the Makita DBO180Z / XOB01Z I decided to use only 120 grit paper as the benchmark for comparison, reasoning if a certain disc performs well in a middle grit, it should perform similarly at higher and lower grits as well. I hooked up my trusty little budget model shop vac for dust extraction and devised two tests to run the 14 different sandpaper discs I’d collected through. The first would test performance on hardwood, the second on softwood. The reason for this is just as there are better saw blades for ripping versus cross cutting, sandpapers can perform variably on different density woods.
The most important part of any experiment is not the result, it is the consistency of the method. If you can’t replicate the result of a test reliably, the final numbers are usually fairly meaningless. To that end best practice is to try to control every variable you can, and only alter the thing you are trying to measure. In this case, the sandpaper disc on the machine. I used the same sander, vacuum, and manual technique for every disc, concentrating on applying equal and consistent pressure and keeping the machine moving in gentle sweeping motions. In other words, trying to replicate best sanding practice and not bearing weight down on the device or using the edge which could prematurely age the disc.
Hardwood Performance Testing:
For my hardwood test I used half of an old reclaimed railway sleeper. I am unsure of the species, though it is likely to be Ironbark which scores a massive 14 on the Janka Scale of wood hardness (Radiata Pine is a 3, Tassie Oak is about 6). I prepared the rough sawn surface by sanding it down through the grits to a 120 finish so every disc from the first would have an even playing field. My selected area was knot free and I divided it into two equal sections each measuring about 0.15m2. For each iteration of my testing I used the time honoured method of lightly scoring the wood evenly with a soft pencil and then sanding until the marks were erased.
For my particular sander I wanted to spend no more than 10 minutes of sanding per square metre of wood. With a test area of 0.15m2, this meant that when a disc took longer than 90 seconds to remove the pencil, I would call it done and move onto the next brand. It was kind of like the old ‘beep test’ from PE at school. Just like that dreaded shuttle run I gave each disc one warning, then failed it on the second breech to weed out an anomalies. Quite simply, the better quality the disc the more runs it would get through before taking too long to clear the test area of pencil, allowing me to compare their hardwood performance.
Softwood Performance Testing:
I took a different tact with my softwood testing. Here my intention was to work out just how much pine a single disc could chew through before becoming useless. I knew the best way to measure this would be via weight so I raided my collection of salvaged bed slats and knocked up many, many blanks each beginning at approximately 100g mass to ensure even wood density. Again I checked they were knot-free for consistency and knocked up a little clamping jig to hold them steady while I stood there for what ended up being over 14 hours spread over numerous days with the sander and vacuum running trying to wear the discs out. It would seem I grossly underestimated just how long sandpaper will last when you treat it kindly with no sharp edge to tear it to pieces!
This time my cut off would be 1g of material removal per minute, calculated via 5 minute runs of sanding the pine blanks. After each burst of abrasive action I would re-weigh the blank and record the change in mass, clean the disc with a brush, switch the battery if it dropped under ¾ full, and dive back in. Just as before I allowed the discs to have a warning, then cut them off the second time they failed to remove 5g in the 5 minute allocation. At the end of it all I had converted nearly 1.2kg of perfectly good 19mm stock into sawdust using only 120 grit sandpaper, but at least I had my data on how much of it each disc was responsible for.
Limits and Lessons Learnt:
Before divulging my findings it is important to quickly cover both the limits of the testing and factors that may colour your own personal choices when it comes to selecting the best sandpaper for your shop. First and foremost while I looked at 14 different commonly available discs here in Australia, I by no means covered all available options. Secondly, life is never that simple… let’s start with sandpaper composition.
The majority of sandpaper you buy is made from Aluminium Oxide (AO). It is cheap, relatively durable and even with advances in sanding technology continues to be used extensively. Silicon Carbide (SC) is more commonly used for glass and plastic and I only tested one brand. It is touted to cut faster but not last as long as AO offerings. Both of these materials are known as ‘non-friable’ meaning they wear down and go blunt over time, limiting their performance as they age.
Compare these to the newer and more expensive Zirconia and Ceramic based discs and nets. These materials have been designed to fracture under pressure as they cut, effectively producing new sharp edges continuously extending both lifespan and performance. They usually carry a higher price per disc so they will want to demonstrate significant improvements to represent better value overall. When we throw in the options of traditional paper backed discs vs open weave fabric based nets things get even more complicated.
So here is where consideration is needed when you compare my results to your own situation. The limits of both a 125mm 18V sander with an 11,000 rpm / 2.8mm orbit and a mediocre dust extraction system are going to put these expensive friable discs at a disadvantage. They like a bit of abuse. On hardwood, the sheer toughness of the material and the relatively minimal dust created makes up for this to a degree, but on the pine the softer grain and huge amounts of choking sawdust generated can not only clog the discs, but stop the Zirconia and Ceramic materials from fracturing and producing those fresh sharp edges you are paying for.
If however you were to take a 150mm corded 15,000rpm / 5mm stroke disc sander hooked up to decent suction, well let’s just say while I couldn’t test the theory properly not owning such a tool, the science at least says things would be quite different. I did actually do a quick side test when one of the expensive ceramic nets failed much sooner than I expected. I went to town with it. I pushed it into the wood, used the edge, moved it aggressively against the grain and generally did all the things you are not supposed to do when sanding and lo and behold it absolutely destroyed the piece of pine that just moments it had struggled to scratch. It was just not well suited to my sander, but it may be for yours.
The Showdown Results:
The long hours watching big bits of wood get slowly smaller were passed and have now been blocked from my memory. (There were over 20 of them with the sander running, not counting time downtime, data crunching, questioning my own sanity and what exactly I am doing with my life). The upside was I genuinely love playing in Excel, generating data tables and graphs. The results were particularly satisfying for my workshop at least as they produced lovely degradation curves and pointed me in a clear direction.
There was a distinct winner in the hardwood test, and a standout in the softwood. They were not the same disc and that’s probably how it should be. Our tough Aussie hardwoods are often likened to steel so it is fitting the best performer in the hardwood sleeper test is actually marketed for metal work. Even after 24 runs, a total of over 3.5m2 sanded, it was still smashing out reps at under 8 minutes per square metre which was more than 20% faster than the next best discs which had already approached
the 10 minute cut-off point under the same conditions. It was a ceramic based traditional disc by Norton called the A995 Blaze and as the fracturing technology promised, it went through a long period where it just would not slow down producing the most consistent
and fastest cutting of all 14 discs on the menu.
When I switched out to the bed slats the clear winner was the Mirka Abranet an Aluminium Oxide sanding net that started and stayed above the competition throughout 2 solid hours of testing a single disc. It was singlehandedly responsible for nearly 200g of pine sawdust over that time or about 25% more than the next two closest competitors (which interestingly were also nets).
Finally we have to look at my motivation for this whole escapade, the value. The first, last and best advice I can give here is simple. Buy in bulk if possible. Like most consumables if you pop into the local hardware store and pick up a 10 pack of the latest sanding nets you could be forking over $3 or more per disc. Whereas picking up a box of 50 of a similar product from a smaller specialist Aussie supplier could come in as cheap a $1 each or less. Even with postage you’d be laughing in comparison. It just so happens for me, I mostly work with ply, MDF and pine so I am leaning to giving the softwood results more weight. Throw in the fact the Abranet also performed reasonably well on the hardwood test and comes in at under $1 per disc and it looks like I will changing to a sanding net, but sticking with traditional Aluminium Oxide and forgoing the upgrade to ceramic for now on my little 18V ROS. Which I might add, performed amazingly well during the strenuous conditions it was submitted to over the course of this investigation.
I'd like to give a shoutout to Kerry from "The Sandpaper Man" who helped me a lot during this testing. If you are in Ausatralia, check him out. The "Sia" branded discs, particularly the Siatop 1815 If you’d like to see the exact numbers and outcomes for my particular experiments, then please do come check out Fixit Fingers on YouTube. Here is the full investigation video. I hope you enjoy and find it useful.
Sadly while it seems it is horses for courses and sandpapers for situations, I hope my look into this much maligned aspect of our addiction has at least giving you some guidance towards figuring out what types of abrasives your style of woodworking demands.