top of page

Sanding Sucks, But It Doesn’t Have To

Tips on Sanding and Finishing Your Woodworking Projects

Mike Ziegler

What grit do you normally start on a project? 60, 80, 120? We find that most people start with 80 grit. That’s very coarse and causing you more swirl marks, uneven finishes, and more time sanding. Instead, start with a medium grit at 120. The spectrum of grits ranges from the most coarse grits between “driveway” (12 grit) to “knuckle busting” (60 grit), to 80, 120 and 150 being medium or intermediate grit, and 180-320 being more of a fine grit. Micro-fine/polishing grits starts at 400.

Stain on Wood based on sanding grits

The picture above shows how stain absorbs with different grits or with the progression of sanding. The wood and stain are the same across the board. If you apply stain after only sanding at 80 grit you get a dark, almost painted stain. If you sand too fine, you'll get the 400-grit side, which is blotchy. At 120 grit, you get highlights and lowlights from the density of the wood. Sanding through the grits to 180 results in an even stain application and yields the best result.

Let's look at the maple board above. There are 4 different grits on this board. To achieve the right look, I start on the left and sand the whole board from left to right with 80, then 120 to the right of the darkest portion, and then 180 and finally 400. In abrasives there is a rule that you shouldn’t skip more than one grit in the sequence. See how the results of the stain absorption change across the board? For instance if we have 80,100,120,150,180, and 220 as our available grit range we can start at 100, skip 120, and move to 150. That is acceptable. But if we start at 80, skip 100,120,150 and then go to 180 there will be issues. The depth of scratch for 80 grit is almost 500% deeper than what 180 grit can scratch. Meaning it will take you longer to sand with 180 to remove 80 grit scratches than using 120 between the two. 

Then why start at 100? Because it’s 20% less aggressive and deeper cutting than 80 grit. Sometimes you don’t need that aggressive grain on your project. If you take a hardwood board off the planer or jointer, you do not need 80 grit to remove the machine marks. Instead most of the time 120 works great. 120 is 20% less aggressive than 100 grit. So 80 is 40% more aggressive and deeper scratching than 120 grit. If you have abrasives that are loading quickly (and you’re not sanding pine) then more than likely your grit is too fine for the application you are trying to perform. 

Tips & Tricks

  • Don’t angle your sander to get a more aggressive removal, it will leave a divot.  Try to hone in on your milling process for more even glue seams 

  • Sanding to a higher grit is not always the best idea; be sure to check the manufacturer’s recommendations depending on what finish you are using

  • Use dust extraction when sanding to avoid swirl marks; even a shop vac with the right hose attachment can take your sanding results from acceptable to great

  • 220 grit in woodworking is the start of the burnishing process. Where sanding any finer on barewood will actually polish the wood surface creating an uneven surface for finishes. 

  • Remove residual sawdust between grits; compressed air or tack cloth works great

  • The tool is the sandpaper, and the sander is the machine. Don't overwork the machine because of dull tools. 

The disc is worn, get a new one. 

When to replace sand paper?

When you start with a fresh disc, it cuts quickly, gets the job done fast and you’re on your way to finishing in no time. But have you sanded a table or large surface, only to realize you are pushing down harder on the sander to get the same performance? 

Chris Smith with Klingspor’s Woodworking Shop said it best when he drew a similarity between the need to refresh sandpaper in the same way you need to sharpen your pencil. Think of Aluminum Oxide as a number two pencil. It starts out sharp but dulls as you use it. If you know about # 2 pencils, the number is the hardness of the pencil. Let's call that “2H” and in abrasives we will call that 120 grit. As you use the pencil the sharp edge breaks down slowly making a duller, wider line than when you started, but it never changes its hardness as 2H. Aluminum oxide is the same way in that it starts sharp and dulls with time but that doesn’t change the fact that it is 120 grit. No matter how dull a pencil becomes, it’s still the same hardness - the same is true for sandpaper.  An overused 120 grit sanding disc may feel like it has become a higher grit but it’s really just a dull 120 and will take longer to achieve the same thing. 

The current price per disc is around .40 cents but that .40 cents controls a lot of variables on your projects. The sander you purchased is anywhere between $50 and $400, the wear and tear on your fingers, hands, arms and shoulders can add up later in life. I have seen more professional shops reuse .40 cents to save a dollar, while they are purchasing more backing pads, new sanders, and muscle salves than to change the disc. The pencil is a tool to get the job done and it’s the most effective cost to performance for an artist or teacher. The sanding disc is in the same playing field.

If you haven't become a TMCU member yet, we highly encourage you to do so. We offer live Q&A sessions weekly, full access to video lessons, community forum access, and discounts, free plans, and PDF files to help you grow in your maker journey.


bottom of page