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6 common surface finishing for metal signage

Table of Contents

What is the surface finishing?

Surface finishing is changing the condition and properties of the material surface that combine with core material tightly to achieve the perfect performance, using the technology of physics, chemistry, metallurgy, and heat treatment. The purpose of surface finishing is to meet the product’s corrosion resistance, wear resistance, decoration, or other special functional requirements.

Why is surface finishing necessary on metal signage?

Remove or minimize scratches and unnecessary coating to improve the metal surface’s corrosion and wear resistance

The metal materials will produce oxide scale, rusting, welding slag, rust, oil, and other dirt during the production process, transportation, storage, etc. If we don’t clean these unnecessary coatings before the subsequent production process, they will affect the bonding force and corrosion resistance between the coating and the core metal; when we do the protective layer on the surface, the metal signs will pretend to rust in a short time. The result is that the coating peels off and affects the mechanical properties and lifetime of metal products.

Therefore, surface finishing is an important guarantee and measure to obtain a high-quality protective coating and prolong the lifetime of the metal signs.

Enables ordinary materials to obtain surfaces with special functions

Surface finishing is an old technology since there are human beings on the earth.

Primitive people lived in caves and made tools from stones and animal bones, and they used grinding technology to make the tools sharp edges to get more food. When they are not worried about the food, the decoration, and variety of function has become the trend.

Lately, painting finishing is as vital as grinding technology. In the late Paleolithic period, people used mineral dyes to paint and paint small personal entertainment items. In the Neolithic period, the invention of pottery made the original color coating technology develop to its peak, forming the famous colored pottery art in history, which opened the prelude to surface treatment coating technology.

In modern society, people use different surface treatment methodsaccording to their needs for products, such as mechanical pretreatment, chemical pretreatment, electrochemical pretreatment, degreasing,de-rusting, trimming, pickling, film cleaning, blasting, conversion treatment, etc.

Save energy and reduce costs

Surface finishing prolongs the lifetime of the products, reducing the frequency of product replacement. It saves the use of raw materials and energy in the production process.

For example, If we want a luxurious gold look but with a limited budget, we can use an electroplating finish on stainless steel to achieve it. Stainless steel materials are a standard and cheaper option than brass or bronze.

6 common methods of surface finishing


The brushed finish is a surface treatment method that produces horizontal or vertical grain lines on the metal surface by grinding. It can reflect the texture of the metal material.

According to the size and shape of different products, there are two main ways of brushing: manual and mechanical. Typical hand brushing is primarily used in 3M scouring pads, and mechanical brushing uses a fine bristle brush on a belt or wheel that can move in the same direction the whole time.

Brushing is usually applied for stainless steel, aluminum, and brass surfaces. We often spray a clear anti-fingerprint oil on the surface for a longer lifetime and easier cleaning.

What is a #4 brushed finish?

When we measured the roughing grade and the number of grit lines, we specified the values #3 finish, #4 finish, and #5 finish, etc. Higher numbers indicate a smoother surface.

Line Grain gradeReference Grit
#3 FinishingRough grinding60-80 grit
#4 FinishingCommon used in Architectural Finishing
(fine polishing grit lines that are uniform and directional in appearance)
80-120 grit
#5 Finishingcommonly used for the medical and food industry120-240 grit
#6 FinishingFine and reflective finish240-280 grit
Grit: Measures the number of scratches per linear inch of abrasive pad.
Brushed grit effects on stainless steel (#60, #80, #120 from left to right)

Spray painting

Spray paint is a liquid paint that sprays the coating through the air onto a surface with a spray gun.

A perfect painting for signage depends on familiarity with the sign’s production process and the painter’s rich experience. And it makes your custom signs be noticed quickly and stand out.

If you want more details about spray painting, please refer to this article: How to get the perfect paints and finishes for business signs.


Electroplating is one of the common surface finishes. It attaches a metal coating on the object of a different type of metal sign using the principle of electrolysis.

The metal to be plated is used as a cathode, and the coating metal is used as an anode; through the electric charges, the metal ions move on to the plated metal surface.

For more details about plating, please refer to this article: How electroplating is used in custom signs.

Stainless steel signs are usually suitable for electroplating. Standard plating colors are as follows.

electroplating colors

● Brushed/Titanium Gold
● Mirror/Titanium Gold
● Brushed/Rose Gold
● Mirror/Rose Gold
● Brushed/Champagne
● Mirror/Champagne
● Brushed/Titanium Black
● Mirror/Titanium Black
● Brushed Antique brass
● Brushed/Antique Copper
● Brushed/Antique Bronze


Sandblasting, also known as shot blasting and sandblasting, uses tiny particles of abrasive sand or spheres against the metal surface by highly compressed air. It makes the surface form fog and matte effect of removing the gold rust, debris, deburring, oxidizing layer, etc.


Grinding is a metal process to remove rust, deburring, smoothening welding joints, creating a sharp edge, etc., with grinding tools to make the metal products look smooth and beautiful. It is usually sanded metal signs before painting and after primed coating.

Grinding discs and non-woven abrasives are necessary for chewing, there are many types of angle Grinder Discs, and we should evaluate the correct grit abrasive to work best. This article can help you know more.


Anodizing is oxidizing the metal on the surface to form a dense protective film to increase the workpiece’s corrosion resistance. Generally, two ways of anodizing are chemical oxidation and anodic oxidation.
The standard material for this surface finishing is aluminum, and it is natural color anodizing and black anodizing.


Surface finish is crucial to producing the perfect signage and contributes to project success.

From the materials purchased to the final products that come out, our veteran team pays attention to each detail. Please get in touch with us if you have additional questions about the metal signage surface finishing.

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