The Ultimate Guide to Stainless Steel Finishes

The Ultimate Guide to Stainless Steel Finishes

At times, choosing the best stainless steel finish is a difficult process.

It doesn’t matter whether you are using stainless steel tube, stainless steel sheet, stainless steel pipe, stainless steel plate, stainless steel bar, or stainless steel rod.

A good stainless steel finishing will improve functionality, aesthetic value or appearance. Ultimately, this also affects the stainless steel price.

This guide explores different stainless steel finishes for your practical use.

Practical Stainless Steel Finish Types in Metal Industry

There are many metal surface finishes you can apply on stainless steel metal. Depending on your intended purpose, it is possible to:

  • Achieve a better aesthetic appearance
  • Get better surface texture
  • Improve durability by enhancing mechanical properties
  • Make stainless steel more corrosion resistant or,
  • Achieve more reflective surface

So, which stainless steel finishes should you choose?

1. Stainless Steel Mill Finish

Mill stainless steel finishes
Mill Stainless Steel Finishes

With a mill finish, you can achieve matte surface finish on stainless steel. In most cases, the matte finish on stainless steel is dull. Therefore, they are not perfect options where aesthetic appearance is a priority.

Additionally, if you intend to process stainless steel further, you can opt for a mill finish. It will still work for you.

The most common options include:

No. 1 Stainless Steel Finish

The surface roughness for the No. 1 surface finish is about 4 to 7 micrometers. It has low reflectivity.

You can achieve this surface finish by:

  • Hot rolling stainless steel material
  • Heating and slowly cooling SS (Annealing)
  • Then subject stainless steel to pickling

In the end, you will have workable and ductile stainless steel with no internal stresses.

You can use stainless steel No. 1 surface finish where visual appearance is not a priority. These may include structural applications, air heaters, furnaces, etc.

More importantly, you can still polish the No. 1 surface finishing for stainless steel.

No. 2B Matte Finish for Stainless Steel

To get this matte finish on stainless steel, you will:

  • Subject stainless steel to cold rolling process – you can use a series of dies and rolls
  • Soften and descale cold rolled SS in acid solution
  • Then pass the steel in a series of rollers to make the surface smooth

You can use 2B matte stainless steel finish in many equipment such as chemical, pharmaceutical, and sewage, among others.

Here, the surface roughness is about 0.1-0.5 micrometers. Although the surface looks smooth, it is slightly reflective.

No. 2D Surface Finish for Stainless Steel

Here, you will get a refined stainless steel surface finish. The process mainly entails:

  • Cold rolling stainless steel
  • Annealing material
  • Pickling stainless steel

Looking at the final stainless steel finish, you will have a surface with:

  • 4 to 1.0 micrometers roughness
  • Low reflectivity

Therefore, No. 2D is suitable for surfaces where visual appearance is not a priority. These may include chemical plant equipment, automotive exhaust parts, or roofing accessories.

Therefore, No. 2D is suitable for surfaces where visual appearance is not a priority. These may include chemical plant equipment, automotive exhaust parts, or roofing accessories.

BA Stainless Steel Surface Finish

Unlike the No. 2B surface finishing – here you will add a bright annealing process.

The bright annealing process requires an oxygen-free environment.

Consequently, it prevents any possible oxidation during the process. Furthermore, there will be no scaling.

Since the BA surface finish is slightly advanced, you should expect:

  • 05 to 0.1 micrometer roughness
  • Very smooth surface with the ability to reflect images

BA stainless steel surface finishing is common in food processing plants, home appliances, road mirrors, surgical mirrors, etc.

TR Stainless Steel Surface Finish

Achieving TR surface finish in stainless steel involves:

  • Cold-working stainless steel
  • You will use polished rollers for temper rolling – the process hardens stainless steel

Depending on the rolling process, you can achieve about 6 strength levels. The final stainless steel surface finish is reflective and smooth.

Some common applications include the automotive industry, surgical instruments, machines, etc.

2Q Stainless Steel Surface Finish

First, 2Q is an EN designation in stainless steel surface finish.

Second, the production process is similar to the TR surface finish. Additionally, you require a protective environment for tempering and hardening stainless steel.

The final surface is usually smooth. Therefore, you can use 2Q surface finishing in the automotive and medical industries.

Note: The process is only suitable for martensitic stainless steel.

Mill Finish Stainless Steel
Mill Finish Stainless Steel

ASTM SS Vs. EN Stainless Steel Finishes

Even as you choose stainless steel surface finishes, there are two universally accepted standards. These are the EN and ASTM standards for surface finishing.

EN Stainless Steel Surface Finish ASTM Stainless Steel Surface Finish
1D No. 1
2B No. 2B
2D No. 2D
2H TR
2R BA
2Q

From this stainless steel finish chart, you can see the designation or the number are different. However, in terms of appearance, they are virtually the same.

2. Brushed Stainless Steel Finish

A brushed surface finish is more abrasive than mill finish.

These stainless steel finishes are known for distinct parallel lines on the metal surface. Ideally, they have a muted luster.

Additionally, the brushed stainless steel surface is popular for:

  • Unique decorative appeal
  • Surface is not very reflective

However, even as you choose brushed stainless steel surface finishing, it may reduce the corrosion resistance. Remember, the minute lines or groves may make stainless steel susceptible to corrosion.

Some common options are:

Brushed Surface Stainless Steel
Brushed Surface Stainless Steel

No. 3 Stainless Steel Surface Finish

No. 3 surface finish is an ASTM designation, which refers to 1G-2G in EN standards.

When you want to get a No.3 surface finish, the starting point is critical. For instance in EN standard:

  • 1G implies the starting point will be hot-rolling stainless steel
  • 2G implies the starting point is cold-rolling stainless steel

In the No. 3 surface finish, the surface roughness can be up to 1 micrometer. Of course, the surface will have low reflectivity.

Some common applications include kitchen equipment, parts in food processing plants, etc.

No. 4 Brushed Stainless Steel Finish

Using a 120 to 180 grit belt, you will sand stainless steel material in one direction. Next, you can smoothen the surface using an 80 to 120-grit belt.

The No. 4 brushed stainless steel surface finish is suitable for decorative applications in jewelry, automotive design, architectural structures, air conditioners, and home appliances.

No. 6 Stainless Steel Surface Finish

The EN standard designation for No.6 surface finish is 1k – 2k finishing.

You can achieve this surface finish by:

  • Hot rolling or cold rolling SS
  • Annealing stainless steel
  • Pickling stainless steel
  • Skin pass rolling SS

The result produces stainless steel with a smooth and reflective surface. On average, the roughness is about 0.5 micrometers.

Due to high corrosion resistance, the No. 6 stainless steel surface finishing is suitable for marine, architectural and ornamental applications.

No. 8 Mirror Finish on Stainless Steel

Mirror Polished Stainless Steel
Mirror Polished Stainless Steel

Choosing mirror finishing for stainless steel ensures:

  • Better surface appearance
  • Consistent surface finish
  • An easier-to-clean surface
  • Easily hides surface damages
  • Hides welding effects on a stainless steel surface
  • Improves SS corrosion resistance

You can achieve this mechanically polished surface by:

  • Using finer abrasives to treat stainless steel surfaces, is mostly a mechanical process and it must be progressive
  • At times, you may use special rollers, which resemble the mechanical abrasion stainless steel finishing
  • The process removes deep defects on the stainless steel surface
  • Next, you will buff the stainless steel surface to create a highly reflective surface finish

Currently, the No.8 mirror finish stainless steel is popular in building column covers, reflectors, mirrors, clean rooms, etc.

No. 8 stainless steel finish is ultra-smooth. Moreover, it is highly reflective.

 

EN Vs.  ASTM Standards for Polished SS Surface Finishes

EN Stainless Steel Finishes ASTM Stainless Steel Finishes
1G-2G No. 3
1J-2J No. 4
1K-2K No. 6
1P-2P No. 7-8

3. Patterned Stainless Steel Finishing and Colored Stainless Steel Finishes

When it comes to patterned and colored SS surface finish, there is only one ASTM standard. It is the No. 2D surface finish which compares to 2F in EN standard.

Let’s look at common stainless steel surface finishes in detail:

Type of Surface Finish Production Process Common Applications
2F
  • Starting point is No. 2B or BA mill finishing
  • Then pickling and skin pass rolling stainless steel
  • Produces a low reflective surface finish
  • Application including roofing, chemical equipment, and exhaust systems for automotive, just to mention a few
1M – 2M
  • Production technique varies depending on the pattern you want to achieve
  • Common options have  -one side with a pattern and the other a flat surface
  • Textured appearance
  • Popular in most buildings such as staircases, ladders, etc.
2W
  • Rolling and pressing to produce patterns on two sides
  • You can use both male and female dies
  • Common applications are architectural structures

Comparing the EN and ASTM SS finishing for the two we have:

EN SS Finishing ASTM SS Finishing Type of Finishing
2F No. 2D Patterned Finish
1M none Patterned Finish
2M none Patterned Finish
2W none Patterned Finish
2L none Colored Finish
1S-2S none Surface Coating

4. Colored Surface Finishes for Stainless Steel

You can apply these finishes to:

  • Enhance corrosion resistance properties
  • Improves esthetic appearance

The most common surface finish is the 2L.

Normally, a 2L surface finish is suitable for decorative applications. It is a common designation for all colored surface finishes on stainless steel.

Colored Stainless Steel
Colored Stainless Steel

5. Custom Stainless Steel Finishes

These are special surface finishes that are unique to your applications. They vary broadly depending on your specific designs.

For instance, you may blend two or more surface finishes to achieve special aesthetic or functional properties.

As a result, you may have embossed, etched patterns or non-directional patterns on SS.

At TuoLian Metal, we will help you get a custom and high-quality surface finish for stainless steel.

We have a special stainless steel finish chart – you can choose custom designs for your applications.

FAQs on Stainless Steel Finishes

1. What is the Best Types of Surface Finish for Stainless Steel?

It will depend on the types of mechanical and visual effects you intend to achieve.

For example;

Satin polished finish on stainless steel is a low-cost technique. Additionally, it is practical in many applications.

With grits and an abrasive belt, you can achieve a coarse surface finish, which is uniform. However, the process is suitable for 2.5 mm thick stainless steel. Besides, it is recommended for hot-rolled stainless steel.

2. Which Stainless Steel Mill Finishes are Popular?

For all your mill-finish stainless steel, you can consider the following options:

  • 1 stainless steel finish
  • 2B stainless steel finish
  • 2D stainless steel finish

3. Can you recommend any Brushed and Polished Finishes for Stainless Steel?

Some common options you can consider are:

  • #3 stainless steel finishing
  • #4 stainless steel finishing
  • #8 stainless steel finishing

4. What is Stainless Steel Surface Roughness?

SS surface roughness is the “degree of texture” or “magnitude of peaks and valleys” on the metal surface.

In the U.S.A. we use the term Average Roughness (RA) while in Europe, it is referred to as roughness depth (Rz).

Mostly, the degree of roughness determined whether stainless steel has a smooth surface or not.

5. Which Tools do You Use for Stainless Steel Surface Finishing?

Any finishing operation on stainless steel will require:

  • Abrasives such as aluminum oxide, zirconium, or ceramic powders
  • Tools may include buffers, pipe sanders, belt sanders, flap wheels, brushes, and finishers
  • Chemicals for specialized finishing

6. How to Polish Stainless Steel to Mirror Finish

Mirror polished stainless steel offer a highly reflective surface with very bright characteristics. Well achieving this kind of surface finishing on stainless steel involves series of processes.

Although the stainless steel polishing processes may vary slightly, let’s quickly look as some critical stages:

  • Remove the rough sections which may include weld material or roughly cut sections. Usually, an 80 grit disc will do the job successfully.
  • Remove the minor scratches. Usually nylon discs will handle the process successfully. However, you should use a slow moving disc. At this stage, you can achieve matt satin finishing on stainless steel.
  • Refine stainless steel surface – by moving the grinder disc at low speed, you will refine the satin finish. Usually, nylon fiber alongside silicone carbine abrasive with a fine grade will handle the job perfectly. With this, you will have a brighter surface finish.
  • Polishing stainless steel to mirror finish – using a polishing compound and slow moving fine felt disc pass the grinder on the stainless steel surface.

7. When Was Stainless Steel Finish Standards Developed?

Standards play an integral role for uniformity and consistency in stainless steel fabrication industry. Actually, it is from this that stainless steel finishing charts were developed.

By 1970s, scientists from Britain had begun examining effects of polishing stainless steel. This involves series of tests on rough stainless steel surface and smooth stainless steel surfaces.

Furthermore, by 1980s, many stainless steel fabricator adopted dull polished surface finishes on SS.

In all these, the underlying principle was to maintain or improve stainless steel corrosion resistance. Besides, ensuring surface finish guaranteed minimal damage during any use or any application.

Following series of experiments, the matte stainless steel finish No. 2B, brushed stainless steel finish No. 4 and mirror stainless steel finish No. 8 were developed. Since then, many other stainless steel finishing have been developed for various applications.

8. What are the Various Stainless Steel Finishing Applications?

Best finishing on stainless steel improves the overall performance of the material. It is worth noting that the application requirements will determine the specific applications. Let’s compare some common finishes on stainless steel and their application:

Stainless Steel Finish Practical Applications of Stainless Steel Finishing
Stainless Steel Matte Finish (No. 2B)
  • Laundry equipment
  • Sewage and water processing equipment
  • Pharmaceutical and chemical equipment
  • Paper processing equipment
Stainless Steel Brushed finish (No. 4)
  • Water heaters and air conditioning systems
  • Home appliances
  • Automotive parts
  • Architectural structures
  • Jewelry
Stainless Steel Mirror Finish (No. 8)
  • Clean rooms
  • Reflecting and mirror surfaces
  • Wall panels
  • Surface ornamentation
No. 1 Stainless Finish
  • Gas turbine parts
  • Furnace and air heater systems
2D Stainless Steel Finish
  • Automotive parts such as vehicle exhaust systems
  • Chemical and petroleum equipment
  • Drainage systems
#3 Stainless Steel
  • Kitchen equipment and appliances
  • Food processing equipment

Conclusion

There are many stainless steel finishes you can choose for any application.

As a guiding principle, before choosing any surface finish for stainless steel surface – be clear on what you want to achieve. Whether it is for aesthetic appearance, or to enhance performance characteristics.

For the best stainless steel surface finishes, contact TuoLian Metal now.

More Resources:

Stainless Steel Advantages – Source: TuoLian

One Stop Stainless Steel Supply.

Whether you need stainless steel materials for your business or fabrication projects, TuoLian is your best supplier. You can find all types, grades, and thicknesses based on your needs. Guaranteed that we provide the best quality at a reasonable cost.
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