Lesson #2: Choosing the Right Sandpaper for the Job
Welcome back! If you’ve already read Part 1 of my “Sanding Doesn’t Have to Suck” series, then that must mean you are one of the wise individuals who want to know more about sanding and sandpaper. Clearly, you realize that it makes a world of difference in your woodworking. So congratulations – you’re well on your way to having more knowledge about sanding than approximately 80% of your peers. (Yes, this statistic is totally unscientifically made up, but never let the truth get in the way of a good story.)
In order to make the most sense out of this part of the process, I’m going to break the following information into three sections: Brand Choice, Material Choice, and Grit Choice. This is the easiest way to break down the thought process behind choosing sandpaper for your shop. And if you don’t have a process, hopefully you will after this!
Choosing the Right Brand
Spoiler Alert: There is no “right” brand of abrasives. So go ahead and throw that thought out the door. I’ll be the first to admit, I’ve bought various products from certain brands because of others’ influence on social media. After all, influencer marketing is the name of the game out here on the internet. However, blindly following someone else’s (paid-for) advice isn’t the wisest choice. You need to spend the time genuinely researching, exploring, and testing what works best FOR YOU.
In regard to sandpaper, there are a few brands out there that work a lot with influencers of all sizes. They will happily give out free stuff if you have enough followers, or if you work well within their particular brand parameters. And that’s totally fine, but it doesn’t mean it’s the right paper for YOU. Personally, I will only partner with a brand if I know and love their product. But having said that, free is good, and I’d be lying if I said I haven’t received products from brands for free.
Free Stuff Isn’t Always the Best Option
Unfortunately, the free products aren’t always what’s best for you and your shop. You need the sandpaper that ultimately gives you the best finish possible. For some projects, all you need is the entry-level DIY paper from your local hardware store. But sometimes, you may need a more refined finish which will demand some higher quality industrial-grade paper. At the end of the day, it’s not about the brand at all. It’s always about what’s right for this specific application, and that should be the driving factor behind your choice of abrasives.
Choosing the Right Material
This is where things get interesting. Choosing the right material for the job is arguably the most important part of achieving the best finish. Thankfully for those of us exclusively working with wood, the choice is pretty cut and dry. But for the sake of education, I’ll discuss the four primary types of materials in the abrasive world and their specific applications.
Chances are good that if you’ve purchased any sandpaper from the big box stores, then you’ve used an aluminum oxide sandpaper. This is the most common chemical makeup of sandpaper and is used widely throughout various industries.
Aluminum Oxide sandpaper has a grain that dulls over time. As you sand, your material will become increasingly finer. For example, when you throw your brand new 120 grit disc on your orbital sander, you’ll start out sanding at 120 grit. But by the end of the disc’s life, you’ll be closer to 180-220 grit, depending on how long you’ve used it. While this may sound like a bad thing, it’s actually totally acceptable and has a place among most standard finishing applications.
For woodworkers, anytime you are sanding on bare wood this is the good material to use as you progress through your grit range. The trick, however, is knowing when to move on to a fresh disc so you stay consistent with your sanding. While some might continue to use this material when they are applying finishes, I don’t believe that it is the best material choice when using polyurethanes, oils, or whatever else you’re using to finish your builds.
Now we’re getting into uncharted territory for most of us, and that’s okay. But if you make the switch from aluminum oxide to silicon carbide, you should notice a significant improvement in your finished product. Unlike aluminum oxide, silicon carbide is a friable grain. Pretty much all that means is that as you sand with this material, the grain will fracture and resharpen to the same grit that you had before. In doing so, the grit will remain the same throughout the duration of the disc’s life. Let’s say you are using a 320 grit silicon carbide paper to sand in between coats of oil urethane on your walnut table. When you begin working your way across the table, you will start to fracture the grain of the paper, but you will always be sanding at 320, which in turn will give you a consistent finish.
It is important to note that silicon carbide is not nearly as durable as aluminum oxide, so you may find yourself using more of this material. That’s why you should really only use it in the finer grits when working with wood. Most silicon carbide abrasives are best suited to hand sanding applications where you can really control the amount of force used. Often times, this material is to fragile to use with any sort of machine.
Now, let’s go back to your walnut table. Since you have sanded with the right material, you will probably find yourself pretty happy with the smoothness of your finish without having to spend your time going all the way up to 1500 grit. So go out there and celebrate your nice smooth finish with all of that extra time you’ve saved by making the right abrasive decision!
This is a fun material. Like silicon carbide, it is a friable material. However, it’s a lot more durable and aggressive because of its chemical make-up. Really all you need to know about alumina zirconia is that it is a great material to use in coarser grits when you really need to hog away at some wood. Some companies will even consider this a planing product because of the material it’s capable of removing.
Personally, I wouldn’t recommend this material in anything over 100 grit. I have come across some people that love it beyond that on wood, but I find that it’s best suited for more aggressive situations. In my shop, this material is only used when I need to really get rid of some glue squeeze-out, or when I have some snipe marks from my planer. It’s important to have this material in your shop for these reasons, but it’s not entirely necessary during your typical grit progression.
Ceramic Aluminum Oxide
Alright, so I’ll be honest with you… I’ve actually never used this material on wood before. Though I have used it for testing purposes at work, I have never found a need to use it when working in my shop. Ceramic aluminum oxide, or just “ceramic” as it’s commonly called, has a unique chemical makeup that incorporates properties of both a friable and non-friable grain.
In most cases, this material is extremely aggressive and will ultimately do more damage to your product than you’d like (whether you see it visibly or not). While there are certainly applications for this material, I would strongly advise you to not use it on wood. In fact, most companies won’t even make this material in grits finer than 120. Knowing all that, there isn’t much else to say about ceramic abrasives here.
Choosing the Right Grit Progression
If you’ve made it this far, you must be really interested in sandpaper… or you’re just really, really bored. Either way, thanks for making it this far! And don’t worry, this last section will go by pretty quickly.
Grit progression is largely up to personal preference. What grits you choose to use is totally up to you, but I would recommend that you use the following guidelines when making your decision on which grits to use.
40-80 Grit: Stock Removal
Depending on how rough your stock is, 40 and 60 may be necessary. But for most applications, starting at 80 grit will be the right answer.
100-220 Grit: Basic Sanding Applications
For this part of the process, pick the grit progression that you prefer. Some people like to go through every available grit. Using every single grit can be expensive and time consuming, so most woodworkers will skip grits during this stage. A common choice is to go 120/180/220, but there are plenty of other options depending on your application. Just be sure not to skip too many grits in a row!
Remember to think about your product and planned finish! If you’re building for paint and/or stain grade, you really don’t need to go much past 150 or sometimes 180 grit. In order for the paint and/or stain to be effective, you need to leave some of the grain open for it to soak in. If you’re using a penetrating oil-based finish then you can go a little finer.
Sanding with too fine of a grit on bare wood WILL close off the grain and your product will not truly be protected. If there’s nowhere for the finish to go, it will build up without actually adhering to the surface. In addition to looking bad, this finish situation isn’t very durable at all.
320+ Grit: Finishing Applications
At this point where you have the freedom to choose what desired finish you want. Just remember, these finer grits should be reserved for the sanding of your top coats.
Enjoy Your Sandpaper, Everyone!
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