A 180 grit surface finish is a fine, smooth, lightly brushed or satin texture, often used as a final preparation for paint/stain on wood or to create a soft sheen on metals like stainless steel, offering a pleasant feel and look without being mirror-polished. It creates a surface roughness of around 0.76 micrometers (µm) and is ideal for sanding between coats or achieving a "dull buffed" look for architectural or kitchen applications.
Common grit sizes and their uses
The higher grit number is equivalent to a finer abrasive, which creates smoother surface finishes. Lower grit numbers represent coarser abrasives that scrape off materials much quicker.
Generally, if you're using an oil or clear finish, you can stop sanding at 180 grit. Continue on to 220 grit if you're using a stain or dye. (These colorants tend to amplify swirl or scratch marks.) Sanding to 320 grit creates a glasslike surface, but also one that accepts little stain, if that's your goal.
180-grit polish:
This is the most common finish on decorative tubing and is a brushed or satin finish. The finish is achieved by rotating the tube through a set of polishers, resulting in brush lines running circumferentially around the material.
0.8 µm Ra. Classified as a high-grade finish, this CNC machining surface roughness requires finishing cutting passes to achieve. 0.8 µm Ra is ideal for parts subject to stress concentration and loading. It is also suitable for vibrating parts and moving components.
The Golden Rule of Sanding means not skipping more than one grit through each step of sanding a surface. This is a basic rule anyone should follow whether they are working with metal, wood, or any other surface. Every scratch you make must be removed by the next finer grit.
Wet sanding plastic, in contrast to other wet sanding processes, does require lower grit sandpaper. You'll want to use 180-grit sandpaper for the most aggressive approach. Use 600-grit sandpaper to finish any details. You'd be surprised how easy it is to wet sand plastic back to a shinier, more uniform appearance.
Tips for Hand Sanding Paint
Start with coarse grit (80–120) to remove most of the paint. Transition to medium grit (150–180) to smooth the surface. Finish with fine grit (220–320) to prepare the surface for repainting. Use wet sanding for a smoother finish and to reduce dust.
Extra Fine Grits (320 to 400): Ideal for ultra-smooth finishes and polishing tasks. This grit is commonly used in automotive work or for polishing metal and plastic surfaces. Super Fine Grits (500 to 600): These grits are used for polishing finishes on wood and metal, as well as polishing bare metal surfaces.
A common unit of measurement of surface roughness is by measuring the “average roughness”, which is often communicated as “Ra”. Ra is the calculated average between peaks and valleys on a surface. The lower the Ra value, the less variation between the peaks and troughs on a surface, making the surface smoother.
Remove the Clear Coat by Wet and Dry Sanding
Take the wet 400 grit sandpaper and begin wet-sanding the clear coat material. This is a crucial step in which a canvas is created for the rest of the process, so those in auto body technician careers must be careful to sand the vehicle's surface evenly.
Fine Grit (180-320): Fine-grit sandpaper is used for finishing surfaces. The small abrasive particles gently smooth the surface, preparing it for painting, staining, or varnishing. It's also used between coats to ensure a smooth, high-quality finish.
Over-sanding: Trying to achieve a perfect finish can actually lead to oversanding the joint compound. If you can see the tape, you've removed too much compound. Sanding too much could damage the tape. Ridges: Improper techniques when applying drywall mud can cause raised, uneven lines or lumps, which are called ridges.
The higher the grit, the smoother the file, and the lower the grit the coarser the file. Grit quality is important for file longevity. For natural nails, a fine grit (180-240) is gentle and effective, such as our KB 2 Way 240 grit nail file. Coarse files (80-100 grit) are best for de-bulking acrylic enhancements.
Common Wet Sanding Mistakes to Avoid
Knowing what not to do is just as important as proper technique. Sanding Through the Clear Coat The most costly mistake is sanding through to the base coat or primer. Once you do this, you'll need to repaint. Clear coat is typically 1.5-2 mils thick.
We usually recommend not sanding between coats of touch-up base color paint, clear coat, or primer.
The three biggest culprits that ruin otherwise great projects are: Tipping the sander while it's running, which creates gouges and uneven surfaces that are difficult to repair. Applying too much pressure to the sander, which can cause burn marks, uneven material removal, and premature wear on your sandpaper.
This isn't good for your sander, sandpaper, or workpiece — and it'll tire you out quickly. Pushing too hard with random orbital sanders can even slow down the rotation of the pad. Hold the sander down with enough pressure to keep it flat, but let the sandpaper do the work.
Try this dust extractor when sanding
Ra and Rz are different parameters of roughness.
Ra is the average roughness of a surface. Rz is the difference between the tallest “peak” and the deepest “valley” in the surface.
Previously, surface roughness was calculated by Root Mean Square (RMS), which used the same measure of peaks and valleys but utilized a different formula. RMS is sensitive to larger peaks and valleys, where Ra is not. RMS, or Rq, will mostly appear on older technical drawings as it has been phased out in favor of Ra.
Cutting speed (also called surface speed or simply speed) is the speed difference (relative velocity) between the cutting tool and the surface of the workpiece it is operating on.