For finishing stainless steel, there is a process called “bead blasting” in which fine particles such as glass beads are mixed with air and blasted.
In this article, we will explain the characteristics and examples of bead blasting.

Want more information on glass bead blasting stainless steel? Feel free to contact us.

In this article, I would like to explain the characteristics and examples of bead blasting.

What is bead blast finishing?

Bead blast finishing is a general term used to describe blasting methods in which the media being blasted is a sphere.
Some people call it shot blasting, while others in the industry refer to it as GBB treatment (Glass Beads Blast).
There are several types of spherical media, generally glass or zirconia.
In contrast, finishing with sharp-edged media that is not spherical is often called sandblasting.

When stainless steel is finished, bead blasting produces a beautiful silvery white surface, while sandblasting with sharp-edged media produces a matte, non-reflective design.

The following photos illustrate the difference.
Top row: stainless steel glass bead blasting
The middle section is stainless steel sandblasting.
Bottom row: stainless steel zirconia bead blasting
The bottom row, right, shows glass bead blasting of stainless steel square pipe.

The bead blasting finishing process has many operating parameters such as media type, spray volume, distance and pressure.
Although there is a wide range of variations, it is a delicate finish that requires digital control of the process and surface roughness to ensure repeatability.

Sandblasting, on the other hand, is basically used to prepare the surface for painting or to remove paint.
The reason why sandblasting is the best choice for paint preparation is that the surface is evenly rough with fine sharp bumps.
This makes it easier to apply paint to stainless steel (SUS), which is said to be difficult to apply paint to.

Features

Bead blasting is a very versatile finish that can be applied to stainless steel, titanium, aluminum, copper, and brass.　It can be applied to stainless steel, titanium, aluminum, copper, and brass. Although each machine and equipment is different, it can be used to finish a wide range of shapes, including square and round pipes, channels, angles, and other shapes.

The silvery white bead blasting finish gives an elegant and gorgeous impression like jewelry.
For example, stainless steel bead blasting is ideal for finishing a handrail that gives the impression of a silvery white thread waiting softly.　Naturally, handrail construction and handrail products cannot be manufactured without welding and bending, but if you polish the stainless steel round pipe to remove the oxide film on the surface in advance, complete the handrail, and then finish it with glass bead blasting, you can create a handrail with a beautiful expression.　The stainless steel round pipe (decorative pipe) sold in general is polished to #400. If you want to use glass bead blasting for cosmetic finishing, it is better to choose vertical polishing.　If you think that the buffed surface of the decorative pipe (stainless steel round pipe) you have purchased is too strong, please do not hesitate to choose the vertical one. If you think that the buffing grain of the decorative tube (stainless steel round pipe) you purchased is too strong, we recommend that you use #700 buffing to reduce the polishing grain without hesitation.　Glass bead blasting does not have the ability to grind the surface, so if you use a product with residual polishing marks, you will regret the unevenness in the marks.　When purchasing a glass bead blasting machine, it is advisable to consult with the customer regarding the intended use, application, and installation environment, as this will ultimately save man-hours and unnecessary expenses.
On the other hand, there is no lack of sandblasting, and it is basically used to make up stainless steel thermosensitive rolled materials, plant materials, and plant equipment.　Unlike glass bead blasting, this sandblasting process is not smooth.　Therefore, the risk of contamination and initial rust due to surface irregularities is greater than with glass bead blasting.　The most important point, however, depends on the blasting environment of the sandblasting company.　If many materials, such as iron, aluminum, stainless steel, copper, and various types of castings, are processed together in the same equipment, the iron powder scraped off by blasting will enter the scratches of the stainless steel, and when exposed to the wind and rain outdoors, red rust will appear like rust that is received.

Example of stainless steel handrail produced by bead blasting in white silver (Fukuoka Gokoku Shrine)

variation

Bead blasting finishes, in combination with a variety of conditions and the polishing process known as groundwork, allow for a considerable variety of design expressions.　Semi-glossy finishes, anti-glare effects, etc. are useful for expressing spaces that combine design and function.
We are often asked if it is possible to repair scratches on site.　Basically, this is impossible. The reason is that we manufacture our products using huge equipment in our factory, and we cannot bring that equipment to the site.　In the blasting process, the projectile pressure, irradiation distance, and discharge volume are controlled. Commercially available equipment such as air cannot meet these requirements.　In addition, spraying on site would be an environmental problem since the surrounding area would be covered with sand.　The best option is to have the equipment removed and shipped to the factory.　The factory is equipped with all kinds of equipment, so they can accurately handle everything from refinishing to finishing.

In fact, for high quality custom-made kitchens with welded structures, we ask our customers to assemble the product in its base state and transport it to the factory in its assembled state.　After that, they are transported to the factory for corrective polishing and cleaning, and then bead blasting. In this way, we can provide you with beautiful products.

Lastly, for stainless steel products that involve welding, some people purchase materials in the form of stainless steel sheets and blast correct only the weld area, which at first glance seems easy to do, but this is the most difficult part.　However, this is the most difficult part. It is difficult to match the weld correction only by blasting unless the conditions are quite favorable. Please consult with us.

＜For more information, please visit the following blog.

Beads Blast＿Stainless steel

Bead blasting and sand blasting

Alumina blasting, to improve the appearance

Points to note

Bead blasted finishes have a fine dimpled surface, and if the surface is clean after cleaning, fingerprint residue is minimal.　If the surface is clean after cleaning, fingerprints will not remain on the surface. However, if dust particles and hand oil adhere to the surface, fingerprints and hand stains will immediately become noticeable.

This can basically be avoided by daily cleaning, but it is possible to continue the effect by using MaCoat GC, a fingerprint resistant coating material handled by our company (subsidiary).

【Keep the beautiful design forever】

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We sell a coating solution that anyone can use to prevent fingerprints easily and simply. The fingerprint resistant coating liquid “MaCoatGC” 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.

Specifying bead and shot blasted stainless steel finishes and their applications

Introduction

Bead and shot-blasted finishes produced by the impact of a hard, inert medium onto the steel surface result in non-directional, uniform matt surfaces with low reflectivity.

These finishes have both aesthetic appeal and can enhance the surface properties of stainless steels. They produce similar finishes to those obtained by acid etching. Blasted material can be chemically coloured, combined with rolled patterns, masked and polished or acid etched to create standard or bespoke designs.

The texture of the blasted surfaces vary with the blast media, which include glass, ceramic or lead bead, silicon carbide, aluminium oxide, stainless steel shot or ground quartz. These finishing methods can be used in the specialist finishing shop or under site conditions, i.e. either before or after fabrication.

For architectural applications steel shot or glass bead peened finishes are a good choice for getting a good combination of corrosion resistance from a non-directional surface ‘sheen’ finish.

Comparison of blasting and peening

In blasting the impacting medium cuts the steel surface, removing small amounts of metal from the surface. The resulting surface finish and hence surface corrosion resistance of the treated stainless steel is partly dependant on the blasting medium. Very hard media, such as aluminium oxide can leave a jagged or torn faces to metal peaks on the surface, whereas the softer media, such as silicon carbide give a smoother finish. The aluminium oxide finish can result in reduced corrosion resistance and cleansability compared to silicon carbide of a similar grit size.

In contrast, peening a surface does not remove metal. The impact of the rounded bead blasting medium results in small craters in the surface, giving a dimpled appearance, at a suitable magnification, as metal is pushed aside. The edges of these small craters are not however sharp and so the corrosion resistance and cleansability of peened surfaces compares well with blasted surfaces, for a given steel type and ‘roughness’ of the surface.

It is important that only clean round beads are used in the peening process.

A build up of broken beads in the peening medium can result in an undesirable uneven surface finish being produced and the excessively rough surfaces produced could be prone to staining or micro-pitting in service. The surface of the steel being treated should be cleaned before and after blasting.

Properties of bead blasted finishes

Bead blasting results in a non-directional textured surface with a soft satin reflection and low reflectivity.
This process works well when applied over satin or mirror polished finishes.

A range of coarsenesses can be created, depending upon the media used and the thickness of the material treated. Unlike acid etching, no material is removed from the surface during the blasting process, but the character of the surfaces produced by these two processes are similar.

During peening the surface of austenitic stainless steel is work hardened and surface compressive stresses are induced. There are specific advantages from these surface property changes:
Improved fatigue resistance
Increased surface hardness. The finish has enhanced scratch resistance.
Improved stress corrosion cracking resistance of austenitic stainless steels, (for any given steel type and service environment.)

The surface work hardening can however result in distortion. For this reason blast finishes should not be applied to stainless steel thinner than 0.4 mm. To avoid product distortion on thin sections, blasting on both sides should be considered.

Specifying bead blasted finishes for stainless steel

Bead blasted finishes for stainless steels are not covered in BS EN 10088-2 as a special finish type, (Table 6). Finishes can be specified by considering the blast media, the blast intensity and the coverage of the surface, but should be agreed with specialist surface contractors.

Blast Media

The Architects Guide to Stainless Steel shows the finish characteristics by blast media as follows:

Blast Intensity
Control of the energy of the stream of the blast media is important for ensuring consistency of the finish. This is monitored through the deflection (arc height) of steel test strips that are only blasted on one side.

Coverage Control

Complete coverage of the surface with the peen craters has to be achieved for optimum performance of the finally treated surface. The original surface must be completely obliterated by the peen dimples. The coverage can be monitored by the finishing contractor using fluorescent tracer dye techniques.

The time to achieve 100% coverage can be exceeded and is then expressed as a percentage of that time e.g. 150% or 200% coverage.

At the ‘Member Products and Services’ page type ‘bead’ in the ‘Find What’ box with the ‘Service Supplier’ button selected. Click on the ‘Search’ button with ‘Bead blasting-Surface Finishing’ highlighted to view a contacts list.

Risk of contamination staining or rusting in service

For optimum corrosion performance, fine media should be used which do not embed into the surface. As with other mechanical finishes, media must be kept free of iron contamination.
Steel shot should not be used as a blast medium on stainless steels.
Sand blast media can contain iron / steel contamination and by preference should not be used.
Glass beads are the preferred blast medium.

Applications for bead blasted stainless steel

Applications for blasted stainless steel finishes include structural support members, (e.g. external walkway support arms). Cast glazing fixing and connections. Architectural external and internal cladding, (facades, columns etc.), sculptures and street furniture etc.

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