How To Polish Stainless Steel (The Full Guide)

Stainless steel is used across a wide range of industries, from automotive and appliances to furniture and knife making. In addition to being aesthetically appealing, stainless steel is durable, corrosion and chemical-resistant, and won’t degrade under high temperatures. It is, however, prone to fading over time, which is why polishing is a key factor in its upkeep. In this guide, the team at Red Label Abrasives explains how to polish stainless steel so that it looks as good as it functions.

Benefits Of Polishing Stainless Steel

As stainless steel ages, its distinctive sheen can fade. Although polishing stainless steel helps keep it looking good, there are other benefits as well. The benefits of polishing stainless steel include:

• Aesthetics: When combined with buffing, polishing enhances the metal's surface quality and keeps it looking lustrous.
• Corrosion Reduction: In metals, polishing reduces the number and size of crevices that encourage rust.
• Contaminant Removal: When stainless steel is polished, even invisible contaminants are removed from the surface. These quality issues may be undesirable in some applications.

What Finish Are You Looking For?

Generally speaking, the method and tools you use to polish your stainless steel surfaces and components will be determined by the kind of finish you’re looking for. Below is an overview of the most common finishing options.

Brushed Finish

By brushing stainless steel, delicate parallel lines are created to create decorative patterns. It works well in areas exposed to bright indoor lights or lots of sunshine because it lacks the typical reflective sheen of stainless steel. However, it can reduce the steel's resistance to corrosion, so rustproofing may be needed depending on the application. To make the lines uniform on brushed finishes, a high-grade abrasive is required.

Gloss Finish

Polishing stainless steel to a gloss finish improves corrosion resistance by smoothing crevices where rust can collect. It's perfect for automotive parts with its chrome-like shine, but it needs an adequately prepared surface. After buffing, it can also achieve a mirror-like shine with the help of high-quality buffing compound and a grinder with a polishing wheel.

Matte Finish

Unlike other finishes, matte is unpretentious and requires less time, effort, and expense to achieve. It is commonly used for practical purposes like kitchen or bathroom sinks and workbenches. A matte finish can usually be achieved with one or two buffing levels, such as 240 grit and 300 or 400 grit.

Mirror Finish

With this highly reflective finish, stainless steel achieves its most iconic look. Besides hiding welded metal, it makes cleaning easier. If you want to polish stainless steel to achieve a mirror finish, you'll need buffing wheels with compound or abrasive belts in the super fine grits.

Do You Need to Sand Stainless Steel Before Polishing It?

Sometimes, but not always. If the stainless steel surface only has minor surface imperfections, you can usually deal with them using a polishing compound. Deep scratches, on the other hand, will need to be sanded out.

To determine whether sanding is necessary, locate the most serious blemish on the surface. Use the least aggressive grit you have available to buff it. Typically, it will be a 400-grit compound. If the scratch is still visible, repeat the process with a slightly coarser grit such as a 320-grit metal polishing compound. Clean and inspect the surface again. If you still notice the scratch, you may want to sand it.

Machine Polishing Stainless Steel

Below are the supplies and steps you will need to get a smooth finish using an angle or bench grinder.

Supplies

• Angle grinder or bench grinder
• Buffer and buffing pad
• Abrasive (sandpaper)
• Acetone or alcohol
• Soft sponges or clean cloths
• Polishing compound
• White vinegar (optional)

Step #1: Clean and Prepare the Stainless Steel

Stainless steel surfaces must be thoroughly cleaned before polishing. If left, foreign matter can scratch and blemish the surface, making it look worse instead of better. Remove any sticky residue with acetone or alcohol. Next, clean the surface with warm soapy water and a soft sponge or cloth: do not use steel wool or anything else that could damage the stainless steel.. Make sure the surface is completely dry before proceeding. 

Step #2: Level the Surface

Using sandpaper in the 80-120-grit range, level out any rough areas once you have a clean surface; if the steel is welded, the bead should be removed. Take your time and avoid over-grinding the surface and causing a low spot. For larger pieces, an angle grinder is the easiest tool to use, while a bench grinder may be the most appropriate for smaller items. Make sure that you clean the piece again before moving on to the next step, as any residual contaminants could affect the final product. 

Step #3: Sand the Surface

As soon as the blemishes are reduced, start using sandpaper instead of the grinder. For metals with a mill finish, you can start with paper in the 120-grit range and work your way up to progressively finer grits as the surface becomes smoother. Typically, you should progress from 240 to 400, then 600, and finally 1200 grit. For a mirror finish, you could go a step further with 2000 grit sandpaper.

Set your sander between 4,000 and 6,500 RPM for buffing stainless steel. Be careful to move the sander at a 90° angle to any noticeable scratches. (Every time you change the grit of the sandpaper, move 90° from the previous motion.) As soon as you get the stainless steel piece to an even, satiny finish, you're ready to move on. Conclude by wiping the steel surface with a soft sponge or cloth dipped in water. 

Step #4: Polish

Choose a buffing compound designed for stainless steel: we recommend green rouge or white rouge. Apply a small amount  to your buffer wheel and slowly work the machine up and down the length of the surface. Be sure to overlap your paths to avoid leaving polishing lines on the surface. Just as importantly, keep your buffer moving to keep from burning the surface of your steel. 

Buffing stainless steel removes scratches and imperfections so that debris cannot collect in microscopic crevices. Through the multi-step process, imperfections are gradually smoothed out and the metal's best qualities are restored. Buffing is time-consuming, but it is the only way to repair the surface and give it that aesthetically pleasing and durable mirror finish.

Some Tips for Best Polishing Results

Buffing stainless steel is the most important step in polishing it to a mirror finish. Don't rush, and each time you apply compound to the buffing wheel, take care not to overdo it.

Other tips:

• Be gentle. Since you're just finishing off the piece, you don't need to apply much pressure. 
• Keep your lines tight and as close together as possible. To achieve an even finish, avoid overlapping too much and make sure you always move with the grain. 
• Quickly pass over the piece. Avoid lingering too long anywhere on the surface.
• Keep plenty of clean cloths and buffing wheels on hand so you can swap them out whenever you change compounds. When using different abrasives, it is extremely important to prevent cross-contamination.
• Before going on to the next step, check the piece over for scratches or imperfections. 

Natural Polishing Solutions

If you prefer using natural materials and your stainless steel surfaces only have minor scratches, you can apply the following materials to the problem areas, using a circular motion. Use a soft-bristled brush or dry cloth. Wipe clean when done.

Baking Soda

If your stainless steel simply needs a little brightening, you can apply a small amount of baking soda to a damp sponge or cloth and apply it the same way you would with stainless steel polish. Be sure to go with the grain of the steel as you work, since baking soda is slightly abrasive. It’s also food safe, so it’s a great option for cleaning and polishing kitchen surfaces, utensils, and appliances.

Vinegar

As well as being non-toxic, vinegar removes dirt, grime, and sticky residue from stainless steel. However, you’ll need to dilute it with water before using it to polish stainless steel: if you use straight vinegar on your steel, it will turn black.

Combine one part vinegar with eight parts water. Spray the solution on the stainless surfaces and let it sit for five minutes. Afterwards, rinse with cool water or wipe with a damp cloth. After your stainless steel surfaces have dried, sprinkle them with olive oil and wipe them with a clean cloth.

Dish Soap and Baby Oil

Stainless steel appliances and counters can be cleaned with a small amount of dish soap mixed with water. Rinse their surfaces thoroughly with warm, soapy water. After the stainless steel has dried, apply a light coat of baby oil and polish it.

Red Label Abrasives: A Cut Above The Rest

Although stainless steel is one of the hardest metals to polish, you can restore its original shine. It doesn’t matter how large or small your project is: with the right tools and materials, you can get outstanding results.