Simple Sanding Tips for a Perfect Surface
Sanding is one of those necessarily evils of woodworking. It might not offer the same immediate gratification as fitting a perfect dovetail, but there is hardly a more important step in the finishing process. For many people it can be tempting to rush through sanding, to slap on a finish, and to be done with a piece. We’ve all been there — and some of us might even have been lucky enough to have a solid finished product.
But more often than not, once a first coat of finish goes on, a builder can begin to see sanding swirls, mill marks, and all the other imperfections we missed by rushing through the process. Rushing leaves you with a final piece that just looks plain bad — no matter how much time and effort went into construction.
Whether you prefer using a random-orbit sander, a block sander, or sanding by hand, by following the steps below you can achieve a flawless surface with very little effort.
Where to Begin When Sanding
Before we start, let’s ask ourselves a simple question: Why do we sand?
The vast majority of time that a person will ever sand is to remove machine marks and surface defects from wood, in order to prepare it for finishing. (Read about other sanding techniques and new ways you can use sandpaper in your projects here?) Depending on the severity of these imperfections, usually it is best to start with a coarse or medium grit sandpaper. This is typically in the range of 80-120 grit (lower grit numbers means coarser, or more abrasive, sandpaper).
The first grit of sandpaper that you choose is the most critical because it will be used to remove all major surface defects. After you have chosen and sanded a piece with the initial grit, each subsequent grit of sandpaper that follows is meant to refine the scratch pattern previous grit until you reach an acceptable level of smoothness.
When beginning to sand a project, it’s not always best to start with the coarsest grit of sandpaper you have available. For instance, if your surface only has minor defects, starting with a 60 or 80 grit sandpaper may remove more of the material than you intend. Starting with a 100 or 120 grit sandpaper may be all that you need to remove surface defects–it will also leave you with more material and thickness in your piece. Perhaps most importantly, it also means as little sanding as possible.
Working Through Each Grit of Sandpaper
Once you’ve sanded with your first grit, continue to each subsequent grit in sequence. You can use the chart below to determine your sanding sequence, depending on which grit you began with (we recommend sanding to at least 220 grit).
It may seem like a tedious exercise to go through each grit between your starting and ending values, but you’ll save yourself a lot of time, energy, frustration, and money by using each grit and not skipping intermediate grits in between.
60 → 80 → 100 → 120 → 150 → 180 → 220 → 320 → 400 → 500+
Sandpaper works by cutting small channels into the surface of wood. Coarser grits cut deeper channels than finer grits. If we start with 80 grit and move directly to 220, it will take a long time (and a lot of 220 paper) for the channels the 220 grit makes to reach the channels left behind by the 80 grit paper. However, if we proceed in the proper sequence, it’s going to take each paper very little time to reach and refine the scratches left by the previous grit.
Proper Sanding Technique
Follow these sanding techniques to achieve a perfectly flat and smooth surface.
- Use light pressure.
One of the most common problems people make when sanding is using more force than is necessary to actually smooth a wooden surface. Pressing too hard leaves deeper scratches that will take longer to remove, and which can cause wood dust to burn and adhere to the sandpaper, reducing its effectiveness. The sander’s weight is all the pressure that is required.
- Slow down to speed up.
If you’re using a power sander, sand slowly across the wood’s surface, spending a few seconds in each location for each grit you use. Do this, and you won’t need to repeatedly sand the same spots with the same grit paper.
- Don’t skip grits.
Use every grit between your starting and ending grit.
- Remove dust between grits.
At the very least, clean your surface of all wood dust after each grit of sandpaper that you use. If you’re using a power sander, connect it to a shop-vac or dust extractor.
Safety Considerations for Sanding
The volume of wood dust created while sanding can create health and respiratory issues if not adequately managed. You can protect yourself with a dusk mask or a respirator while sanding, which will keep your lungs safe while dust is suspended in the air. However, once that dust settles, it can cause problems when it comes time to apply finish to your piece.
We never recommend against wearing a respirator, but the best way to deal with wood dust while sanding is by collecting it right at the source. The only sanders that excel in this area are random-orbit sanders with dust extraction. Many random-orbit sanders come with vacuum bags that attach to a port on the rear end of the sander. If you have one of these, we recommend connect it directly to a shop vacuum or dust extractor.
In addition to the safety concerns this addresses, collecting dust at the source also improves sanding efficiency. Dust left on the surface of wood while sanding acts as a barrier between sandpaper and wood, reducing its ability to sand. Accumulated dust also rapidly heats up while sanding. This can lead to burning on the surface of your project and/or the dust bonding to the sandpaper.