Which Sandpaper Grit is right for your job?
Sandpaper, like many things in life, fall on a spectrum. Ranging from very coarse and abrasive to very fine and smooth, it's up to you to choose which is right for your job. That's where we come in! Each grit – or grade – of sandpaper has a different role to play in the process, and to use it correctly, you must know how to choose the right one.
Grit Sizes
Sandpaper is sized in grits, the most common grits ranging from 40 – 400 grit. The lower numbers paradoxically signify the larger, coarser grits, and the larger numbers indicate a finer, less abrasive sandpaper. It's a little confusing at first, but you'll get the hang of it in no time!
Sandpaper is measured by the number of holes per square inch. For example, a piece of 150-grit sandpaper uses abrasive particles that were sieved through a screen with 150 holes per square inch.
To easily identify the grit of the sandpaper, the number is almost always clearly printed on the back of each piece.
What next?
Lets begin!
When evaluating the task at hand. first identify the quality of the surface. If the surface is rough and in need of some serious TLC, you'll most likely need a coarser grit of sandpaper. An old wooden table, covered in dents, divets and debris, would likely need a 120-180 grit sandpaper to get through the rough surface. If you're removing paint or varnish, an even lower grit of 60-100 will likely be necessary to cut through the existing finish.
If the surface is a large area of wood, metal or other materials, a lower grit will allow you complete the job with a much greater level of ease. Due to the high coarseness, it will cut through the fibers on the material with less resistance. A lower grit can even be useful for shaping an edge where leaving scratches isn’t an issue.
For smaller, more delicate applications, a larger grit size will be necessary. A finer paper will naturally only remove a tiny amount of material, smoothing the surface down without removing a finish or sanding away fine details. Another added benefit of a larger grit is that it leaves very little scratches behind, so for minor touch ups, it will allow you to have a much greater level of control over the quality of the finished product.
Oz General Store tip: Start with a lower grit to remove the bulk of the material, and progressively work your way up the grit sizes as the surface gets closer to the finished product.
Sandpaper Grit Chart
40 - 80 Grit (Coarse Sandpaper)
Coarse grit sandpaper is ideal for:
- Shaping wood
- Removing old paints, blemishes and finishes
- Rough lumber
- Shallow scratches
- Saw blade burns
These are the coarser grits on the spectrum, and are often reserved for the removal of large, rough surface areas. With these grit sizes, removing large amounts of surface area and blemishes can be done with ease, and you'll find yourself able to cut through even the toughest marks and unwanted spots.
They can also be quite effective at shaping and rounding edges/corners. However, they are not recommended for finer details or edges/corners that you want to keep sharp, as a coarse grit can cut away at details you want to keep and can smoothen things you don't want smooth.
100 - 180 Grit (Medium Sandpaper)
Medium grit sandpaper is ideal for:
- Prepping for polyurethane and enamel paints
- Surface irregularities
- Sanding of soft woods
This is the most common range of sandpaper used, as it is quite versatile and makes a good starting point for most projects. With the grits in this range, you'll be able to complete a broad range of tasks, simply by applying more or less pressure to your project. Work away tough, difficult materials by applying more pressure, or preserve finer details by easing up on the pressure.
Oz General Store tip: 150 grit sandpaper is ideal for sanding down wood surfaces that are being prepared to be painted. While it doesn’t leave large scratches on the surface, it does leave a little “tooth” in the wood, which gives the paint something to grip onto when painting.
200 - 280 Grit (Fine Sandpaper)
Fine grit sandpaper is ideal for:
- Prepping for latex, acrylics and wood stains
- Begin surface finishing
- Raised wood grain fibers
This is the “Goldilocks” zone for sandpaper used to finish most projects, particularly those which still require a coat of paint or acrylic. In most cases, going beyond 240 grit on wood won’t yield much tangible difference. However, due to the lesser number of holes per square inch, sandpapers in this range are still able to maintain a nice, smooth finish, while also leaving just enough “tooth” for a final coat.
320 - 400 Grit (Extra Fine Sandpaper)
Extra fine grit sandpaper is ideal for:
- Sanding between coats
- Wet sanding
- Smoothing topcoats
- Prepping for finishing oils
- Metal and other hard surfaces
This grade of sandpaper is used to achieve the final level of smoothness on all types of material. With wood, extra-fine grits are usually left for smoothing already painted surfaces between coats. A noteworthy disadvantage to extra fine sandpaper, however, is that often they make the wood so smooth that stains won’t penetrate evenly.
Extra fine sandpapers are also ideal for automotive work, as they work well under wet conditions, while being extremely fine. They are also very strong and able to sand through metals and thick paint, leaving a shiny and silvery luster of the metal on the surface, ready to be primed for further painting.
Want to know about anything else in the realm of sanding and sandpaper? Get in touch!
Also, don't forget that we have sandpaper sheets and rolls available here on Oz General Store! Check out our range of sandpaper products and other abrasives