What is mirror polish brass and Why Do We Use Them?

Welcome to Matt’s Metalworking, in this tutorial I will be showing you a beginner’s guide on how to polish brass with a mirror finish by hand. I’m just using a piece of raw brass, so you can see it’s quite rough and it’ll definitely be more work intensive than compared to a machined piece or something that is already finished just needing to be refinished.

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Required Tools

• bucket with water
• backing pad
• clean soft cloth

Required Materials

• 600 grit wet/dry sandpaper
• grit wet/dry sandpaper
• grit wet/dry sandpaper
• grit wet/dry sandpaper
• alloy polish

Depending on the surface’s damage, this will depend on what grit of sandpaper is required. For this I am starting out with 600 grit sandpaper, this needs to be a wet/dry compatible paper. The sandpaper needs to be pre-soaked before we start the sanding process. I have a bucket of water beside me, if you wish you can mix in soap to help with lubrication that can allow for a finer finish. For this tutorial, I’m just using straight water.

The heavier surface damage, the lower the grit is required. However when you go to a lower grit, this also means more material will be removed, and as you increase to a higher grit, slightly more work is required to remove those heavier grit scratches. When starting out with that first grit of sandpaper, most of those surface imperfections should be removed. This is basically the rough in step. Rinse off the surface to remove any access sanding material and always keep the sand paper well lubricated.

Moving up to grit wet/dry sandpaper. The reason I am wet sanding is so that the dust is kept down and we can achieve a finer finish. The black backing pad I have keeps even pressure on the surface with minimal distortion as what you may find when only using your fingers. For irregular shaped surfaces, you maybe able to use a foam backer instead.

For an addition example using an abrasive pad. Just like sandpaper, these too are available in various grits and is typically distinguishable by the color of pad. The maroon pad is listed at about 320 to 400 grit. These can be used with water as well which I am doing here. These pads are great for irregular shaped objects, but they don’t necessarily remove surface imperfections. Instead they smoothen or round off those imperfections. Sandpaper with a backer on the other hand can promote more of a smooth surface.

Moving up to a finer grit, this pad is green and rated at about 600 grit. Always keep the area well lubricated and rinse away excessive material. I’ll be stopping here to demonstrate what happens when you don’t use a fine enough grit before moving onto a polishing compound.

This illustration helps explain the difference between using sandpaper and abrasive pads. Starting out with the existing surface and surface imperfections, each has high and low spot. With the sandpaper and a backing pad at the top, this removes all material evenly and also takes down the high spots from cratering marks. If you want those deeper marks to be completely gone, more surface material needs to be removed unfortunately. So this can result in more work, thinner surface, and changed dimensions.

Using abrasive pads, these may leave the surface uneven and won’t remove surface imperfections complexly. Instead it’ll round off those marks and cratering. Which methods you go with is really your personal preference and what type of shine you want to achieve.

Now moving onto the polishing stage. You can use a polishing compound such as what is used on automative paint or a metal or alloy specific polish. Here I am using an aluminum wheel polish.

I typically start out with soft paper towel first as metal polishing can make clothes quite dirty and hard to clean afterwards. Paper towel can be easily thrown away and we can finish with with a soft cloth at the end. Apply the polish to the cloth and work it into the surface. I will be polishing both the areas I used sandpaper and then the abrasive pads.

Work the polish into the surface, apply more polish when needed, and wipe away if the old polish gets too excessive. The polish will turn black which is perfectly normal as it’s removing a very light amount of material.

Once the surface is almost finished, finish up with a light amount of polish and a soft cloth.

And this is what we’re finally left with. You may see some mild scratching, therefore more polishing would be needed. There is still some surface imperfection, but they are much less than compared to what we started with. Finishing up with the 600 grit abrasive pad, while it’s still somewhat shiny, it doesn’t have the clarity than compared to using a finer grit. You can also see the existing raw finish before we started on other parts of the brass bar.

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One of the polishing processes is called “mirror finishing,” which literally means a processing method to finish the surface of metal like a mirror. However, there are many things that are still unknown, such as the difference between the scope generally recognized and the scope recognized by the metal processing industry.

In this article, we will discuss

“What is a mirror finish?
“What are its characteristics?
“What kind of variations are there?

and “What variations are there?

What is a mirror finish?

A mirror finish is a design polishing finish that gives a mirror-like reflection to the surface of metal. There is a slight difference between the scope of our industry and that of the general public.

Let me explain using a commonly manufactured stainless steel mirror plate.

The products that are generally recognized as having a mirror finish as a finish that reflects the face nicely are

1, Buffing #400

2, Gloss buffing finish #600

3、Buffed mirror finish NO.700

4、Glazed mirror finish NO.8

5、Mirror finish #800

These are the product lines that we have.

In our industry

mirror surface means 3, 4, and 5.

If you want to learn more, please visit our website mirror polish brass.

However, in general

1 to 5 are recognized as mirror surface. In particular, #400 mirror polished products are often referred to as “polished”. Therefore, it is better to tell us the purpose of the product when you buy it.

For more information on polishing stainless steel, please see below.

Introduction of mirrored plates of stainless steel, etc.
Why do we polish?

A mirror finish is one in which the surface reflects like a mirror, but it has a wide range of uses depending on the grade and design expression.　The higher the grade of the mirror finish, the more difficult it is to repair scratches.

The stainless steel #400 buffing plate is the most widely used of all stainless steel mirror plates, and is widely used for various purposes.　This product is a representative of stainless steel surface finishing that has been loved for more than half a century.　It has been used in a wide variety of applications, from medical equipment, food equipment, and vehicles to semiconductor manufacturing equipment and display device manufacturing equipment.　On the other hand, stainless steel #600 or higher mirror surface plates are widely used for interior and exterior construction and equipment.　Of course, the higher the grade, the higher the price. Therefore, it is not possible to use only the highest grade, so customers can choose according to their usage.　In the case of highly designed architectural work involving welding process made of stainless steel, #700 is the one that can be reworked.　No.8 is recommended if the defective part can be made not to show by technique.　However, if you want to use it as a mirror, #800 or more from a flat stainless steel plate with a thickness of 2.0 mm or more is preferable.

In general, SUS304 stainless steel mirror plates are the mainstream, but mirror processing is also possible for stainless steel grades such as SUS316 with high corrosion resistance and SUS430 with chromium, depending on the application.　Please consult with us from the design and functional aspects so that we can provide you with the most suitable product.

As for the finishing method and finish of the welded area, stainless steel #400 buffing plate is finished with sisal buffing.　After finishing the welded area with a sander, it is raised to about #600 with paper, and then finished with sisal buffing to achieve #400.　The point to note here is to match the buffing grain.　If the buffing grain is out of alignment, going straight, or facing diagonally, the design will be lost.　Please be careful.

For buffing mirror finish of #600 or #700 stainless steel, after finishing to #400, use a surface buffing tool to remove the buff marks and increase the luster.　Although it is not necessary to match the buffing grain as much as # buffing, the direction of the buffing grain should still be the same or it will look crossed and mottled due to the reflection.

As for the correction method for stainless steel NO.8 and #800, it requires a lot of technique. This cannot be done with the same grinder that I have used in the past, but with a polisher that rotates in a circular motion.　After grinding up to about #700, the final polisher is used to finish the work, but since the liquid is quite special, know-how and technique are required.

Features

Mirror-polished finishes vary in difficulty depending on the grade. Special production methods and equipment are required.

For small items, #400 or so, it is possible to finish them once the technique is relatively mastered. Applicable materials include stainless steel, titanium, aluminum, copper, and brass.

However, there are some finishes that cannot be applied depending on the grade, so we ask for inquiries on a case-by-case basis. In addition, although each facility is different, one of the main features is that we can finish a wide range of shapes, including plates, square pipes, round pipes, channels, angles, and other types of steel, as well as fabricated shapes.

The beautiful mirror-like finish is the basis for creating any design pattern.　There are many types of stainless steel mirror sheets, so if you want to reduce reflective pollution outdoors, you can use a low-reflective stainless steel mirror sheet as a base for forming textures.　In addition, if you want to add reflection elements, you can choose a stainless steel mirror plate with high resolution.

[Click here for examples.]

Arabesque pattern Stainless steel

Metal pyramid

For other detailed articles on stainless steel mirror finish, please see the following

Lighting effect on 3D stainless steel panel

variation

Stainless steel mirror finishes are available in a variety of grades, but there is a wide range of design expressions, such as texture formation on the mirror finish, partial design processing, partial coating, and vapor deposition processing.　When deburring, which is a process that occurs in metal processing, if the burr bites into the mirror surface, the surface will be blurred, so depending on the shape you want to buy, you may need to select a product that allows post-processing correction or change the processing procedure.

Therefore, depending on the shape you want to buy, you may need to select a product that can be post-processed or change the processing procedure. Since stainless steel mirror-finished plates are materials, you can achieve fast and efficient production by deciding on the grade of stainless steel mirror-finished plates that will be your star and selecting the processing method with the finish in mind, based on the product you want to produce.

Click here to see actual examples of use.

Golden Water Drop
Golden Stainless Steel
Mysterious Stainless Steel Mirror Ripples
JEUX D’EAU
水明（SUIMEI）

Cautions

Stainless steel mirror finish has a very smooth surface.　Therefore, it is a very delicate surface finish.

Thanks to its smooth surface roughness, the corrosion resistance is low, but the cleaning is very careful. Cleaning with a sponge or rag containing even a small amount of dust will cause scratches. Furthermore, even if you use clean water, water marks, water stains, and uneven wiping will appear.

Initially, it is a beautiful mirror finish, but for some applications, it may be better to add an extra element.

Incidentally, because of the smoothness of the mirror finish, it is extremely difficult to apply fingerprint resistant coating material such as MaCoat GC, which is handled by our company (subsidiary).

If the surface has an uneven texture, dirt and fingerprints are relatively less noticeable.

[Keep the beautiful design forever

We sell a coating solution that anyone can use to prevent fingerprints easily and simply. The fingerprint resistant coating liquid “MaCoat_GC” can be applied to metal just by applying the liquid. The coated metal is almost invisible to the eye. Since the liquid coating can be applied easily to any shape or location of metal, it is being used in a variety of applications such as three-sided frames of elevators, interior partitions, and artwork. Please contact us directly for purchasing information.