How to Hand Polish Stainless Steel

January 21, 2021
In this post, you'll read:The key to beautiful, iconic stainless steel in any application, from interior design to consumer product manufacturing, is an even polish.

Table of Contents

The key to beautiful, iconic stainless steel in any application, from interior design to consumer product manufacturing, is an even polish. The skill and experience that goes into the preparation of stainless steel can be vast and nuanced depending on the manufacturing process. Add in the fact that many stainless steel finishes are achieved through hand-polishing, and you can see how complicated the process can become. 

Many people have stainless steel in their homes, office, or public building. You know that proper care and maintenance will be the best way to extend the life of your stainless steel and keep it looking pristine. Many appliances use stainless steel in their construction, and polishing them can breathe new life into your machines. 

This is an image of stainless steel application at home.

Consistency is essential when lining any surface with stainless steel, so it is necessary to use trained polishers with experience. The results of hand-polishing can be wildly different, depending on the specific needs of the company using the stainless steel sheets. Let’s look at the three most common hand-polished finishes and how they are achieved. 

Types of Hand-Polished Stainless Steel

Not every design of stainless steel can be hand polished. The machines used to hand polish large sheets can not get into the detailed surfaces of some types of steel like stamped stainless steel or small details with crevices or turns.  

The three most popular and recognizable hand-polished stainless steel finishes are:

  • Mirror
  • Hairline
  • No.4

2B Finish

Before we can discuss the polished finishes, it’s essential to take a look at where they all come from. The base finish for stainless steel sheets is called 2B. This is the most common finish for stainless steel and is found in tons of different applications. It is the untreated surface of a newly-made piece of stainless steel. While it works well in many situations, 2B is plainer than a hand-polished option and won’t stand out in the way most people desire. 

This is an image of 2B finish stainless steel.

Mirror Finish

The mirror finish is precisely what it sounds like: stainless steel polished so finely that you can see your reflection in it. Mirror finish not only looks good, but it increases your steel’s corrosion resistance. By removing all small crevices in the metal where corrosive particles could become caught, you extend the life of your steel. 

Mirror finish works great in wall panels, column covers, and yes, mirrors. This is also the finish used on most jewelry since it catches the light and adds to the brightness of any piece of metal. 

This is an image of mirror stainless steel.

Hairline Finish

The hairline finish on stainless steel sheets is similar to the No.4, but the hairline has one distinction. Hairline finish features a series of scratches, all running in the same direction and at longer lengths than in No.4. This gives longer pieces of steel a sleeker and more fluid design. Hairline finish stainless steel is great for drawing the eye in a specific direction.

This classic stainless steel finish is commonly used in paneling for interior and exterior decorative applications. It is frequently seen on elevators and security devices because it works wonderfully in high-use areas. 

This is an image of hairline stainless steel.

No. 4 Finish

Sometimes called a “brushed finish,” No.4 is a very popular option for customizing stainless steel. This works better in situations where reflective steel may be dangerous. Mirror finish would make a terrible sign near a road; the reflected sunlight could blind motorists. For that reason, No.4 is frequently used in architecture, like in the Gateway Arch in St.Louis, Missouri. 

No.4 has reduced corrosion resistance since its surface has a series of scratches that can host corrosive particles. This makes No.4 a good option for appliances and other frequently handled and cleaned items, such as watches. The decorative scratches on the surface can hide many small scratches that result from use. 

This is an image of stainless steel flask.

Other Types of Stainless Steel

Advanced techniques during production can produce even more fantastic displays of craftsmanship. An example of a stainless steel finish that can not be hand polished is the bead blasted effect. And, of course, for a truly unique or aesthetic style, sheets of stainless steel can also be colored, etched, or stamped. That said, the foundation for all of those types of stainless steel is an even, polished finish. 

The Hand-Polishing Process from 2B

The following hand-polishing processes all follow similar steps, but different tools and techniques will result in a different finish. Achieve a better finish by planning out your steps and gathering the necessary equipment beforehand. 

Mirror Hand-Polishing

Mirror finish is straightforward because it is either a mirror or not. There is not a lot of variation you can get away with here. To turn a sheet of 2B stainless steel into a mirror, start with a flat surface. Then, you’ll work your way through a variety of sandpapers, gradually getting finer. How fine of a grit you go up to is dependent on your needs and the quality of the steel. Low-quality metals can not be polished to a fine mirror finish. 

Using a hand sander/polisher, choose a disc of sandpaper around 120 grit. You’ll want to keep your sander between 4,000 and 6,000 revolutions per minute (RPM) for this entire process. You can start at a 90-degree angle to remove any larger scratches or welding marks. Then, once everything is uniform, you can move to the next level of grit. 

This is an image of sandpaper.
This is an image of sandpaper catagory.

After 120 grit, double up with a 240 grit sandpaper and sand the entire surface. Repeat this process with 400 grit sandpaper and then 600 grit sandpaper. It is around this point when you’ll start to see the reflective properties of the stainless steel show themselves. 

To further improve your mirror finish, continue this process of sanding the entire piece with 1200 grit sandpaper, and then finally 2000 grit sandpaper. Now, the sanding is over and it is time to polish the stainless steel up to a high shine. 

Lower your sander to the range of 2,000 to 3,000 RPM, so you don’t destroy your polishing attachments. Alternatively, you can purchase a separate hand polishing tool, if you are working on a series of stainless steel sheets, and want to separate tasks with another person. A polishing compound and polishing mop attachment for your sander can hand polish the stainless steel the rest of the way. Apply polishing wax to the wool pad attachment for your tool and then apply a smooth, even layer to the steel. Once you can see your reflection, you’ve successfully hand polished a mirror finish. 

This is an image of hand polisher.
This is an image of polishing wax.

FTSSS has also gone one step further, to make their “Super Mirror” line of stainless steel. This involves going to grits on a micron level, which means increasing the grit size to 8,000 for a standard mirror, 8,000 to 10,000 grit for a fine grind, and 10,000 for an ultra-precision grind. This can make the stainless steel even more beautiful and reflective, and it is the best option when a clear image is needed, like in a perfect mirror or security reflector.  

Hairline Hand-Polishing

Start with a 2B piece of stainless steel, and make sure that the surface you will be polishing is flat. This process works best with sheets of stainless steel. If there are any weld marks or inconsistencies from the manufacturing process, use heavy grit sandpaper to buff them out before you start. Knowing what your end result should look like will be more helpful with hairline finish, since there are so many options available to you. The length of the scratches, the grain direction, the depth of the grind, and the overall continuity of the grain are all factors that can be individually adjusted to make a piece of steel into the design your application needs. FTSSS offers the standard straight grain hairline finish, and can also produce cross-grain hairline and diagonal hairline finishes on our stainless steel sheets. 

This is an image of stainless steel sheets.

With your hand sander, grind the surface to a fine-grain polish of around 240-320 grit using a belt or oscillating disc. Then, make a series of long grinds running parallel, holding the sander at an angle, to produce the signature hairline effect. 

No.4 Hand-Polishing

No.4 finish is less controlled than hairline to produce, but getting the finish you want for your final product still requires an even layer of sanding applied to the surface. The main difference between No.4 and hairline is the direction of the grain. While hairline finish has a long, straight grain, No.4 has a series of grinds going in every direction to create a more uniform surface. 

The look of your No.4 finish will be determined by the grit of sandpaper that you stop at. It will still go in the order of rough grit to fine grit like mirror finish did, but you can stop at different levels for unique aesthetics. FTSSS commonly makes grit levels of 180, 240, 320, and 400 for their No.4 sheets. Anything beyond that tends to look like a dull or underdone mirror finish. 

This is an image of No.4 stainless steel sheet.

For a basic No.4, you’ll only need a 120-180 grit belt or disc and should make sure to grind in a motion that covers the entire surface at random, yet evenly. If you follow one direction too much, it may create the appearance of a planned grain in parts of the sheet, which could ruin the desired effect.  

What Next?

After a stainless steel sheet is polished, it is finished. Unless, of course, you want even more customization options. After a piece is entirely hand-polished to the desired look, you can begin making it more unique to your needs. After polishing is when to start the process of coloring the steel or adding a finishing coat to protect the surface. Common additions include scratch resistance coatings, corrosion resistance coatings, and fingerprint prevention coatings. This is also when you can start to emboss, stamp, or etch designs or patterns into your stainless steel. 

This is an image of stainless steel sheets.

Wrap Up

Now that you know what you’re doing, it’s time to grab a hand sander and get to work. Or, trust expert stainless steel artisans with more than ten years of experience doing this type of work. The production team at FTSSS is here to answer any further questions you may have about the types of stainless steel finishes that are available or possible. For more examples and options of stainless steel sheets, check out the FTSSS catalog (RECENTLY UPDATED) to see what we are making lately. 

Hi, I am Linda, FTSSS blog writer . I have been working on stainless steel  since I graduated from university. How time flies!  13 years have slipped away from me. ‘Stay hungry, Stay foolish.’ I am walking steadily on the road of seeking knowledge every day.

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