Hairline brushed stainless steel sheet

A hairline brushed stainless steel sheet refers to a stainless steel plate surface treated with a hairline brushing process, creating ultra-fine, uniform linear textures that resemble fine hair strands. This finish is highly popular for its sleek, modern aesthetic and functional advantages.

Key Characteristics

• Texture:

◦ Unidirectional, delicate linear patterns (achieved with fine abrasive grits like 320#–600#).

◦ Matte to semi-gloss appearance, with low reflectivity (non-mirror finish).

• Surface Quality:

◦ Smooth to the touch, hiding minor scratches and imperfections.

◦ Resistant to fingerprints and smudges, making it easy to maintain.

Processing Steps

1. Pretreatment:

◦ Clean the sheet to remove oil, dust, or contaminants (e.g., using degreasing agents).

2. Hairline Brushing:

◦ Use soft abrasive brushes (nylon or non-woven) or fine-grit abrasive belts.

◦ The brush/abrasive moves uniformly across the sheet in one direction, creating consistent, parallel lines.

3. Post-treatment:

◦ Clean residues and apply protective coatings (e.g., oil, wax, or PVD plating) to enhance corrosion resistance and durability.

Common Materials

• Typically applied to austenitic stainless steel grades like 304 or 316, known for their formability and corrosion resistance.

Applications

• Architecture & Decor:

◦ Interior wall cladding, elevator cabins, stair railings, and decorative panels (popular in modern or minimalist designs).

• Appliances & Kitchenware:

◦ Refrigerator doors, oven panels, kitchen sinks, and countertop trim (practical for high-use environments).

• Electronics & Automotive:

◦ Laptop/phone casings, automotive trim pieces, and signage (combines style with scratch resistance).

• Industrial & Medical:

◦ Machinery enclosures, medical equipment surfaces (due to ease of cleaning and hygienic properties).

Advantages

• Aesthetic Appeal: Provides a sophisticated, understated look suitable for both commercial and residential projects.

• Functionality: Reduces light reflection, hides wear, and offers better grip in some applications.

• Cost-Effective: Less labor-intensive than mirror polishing, ideal for large-scale production.

Maintenance Tips

• Wipe with a soft cloth and mild detergent to remove stains.

• Avoid harsh chemicals or abrasive tools to preserve the texture.

This finish is a versatile choice for applications requiring a balance of elegance, durability, and practicality.

Cleaning Methods

Daily Cleaning

Wipe gently the surface of the stainless steel sheet,using a fine cotton cloth soaked with either soap water or neutral detergent (diluted with 30-40% water). Rinse with water and use a fine cotton cloth to dry and absorb excessive water.

Finger Print Cleaning

It can also be substituted by organic solvent such as acetone or alcohol. Rinse with water and use a fine cotton cloth to dry and absorb excessive water.

Heavily Stained Cleaning

Grease or oil marks on the surface can be removed by organic solvent such as acetone or alcohol. Rinse with water and use a fine cotton cloth to dry and absorb excessive water.

Warning:

Never use bleaching agents,abrasive cleaners or chlorinated chemicals as cleaning agent,as they will cause discoloration and damage on the surface.

Handling Precautions

Never let Hydrochloric Acid Solution,Sodium Hydroxide Solution,Bleaching Agents,Abrasive Cleaner as well as Cement Water make contact with the stainless steel sheet as all the above-mentioned agents will contaminate the stainless steel  surface with heavy stained marks.

Do not perform soldering or welding on the stainless steel sheet as it will cause color changing on the metal surface.

Do not let the PVC protective layer stay on the stainless steel surface for more than three months from the date of delivery as the remains of the adhesive glue might leave on the stainless steel surface.

Do not let iron powder,iron nails as well as other external materials stay on the steel surface because they can damage the anti-rusting nature of the stainless steel. Daily maintenance is essential,please refer to the cleaning methods above.

Durability and life expectancy for stainless steels in external environments

Introduction

The most important corrosion consideration with stainless steels is pitting.
Micro pitting is manifested as surface rust staining and is generally considered unacceptable for a material
basically selected for its aesthetic appearance and corrosion resistance.
Analysis and extrapolation of pit depth data gathered from atmospheric exposure test programs can be used
as a durability guide. (This work was done by Corus (British Steel) Technical)
It must be borne in mind that staining from micro pitting may result in rejection of the steel on aesthetic
grounds, long before pitting has perforated it.

Factors affecting durability

The durability of the stainless steel depends on:
steel grade
environment
surface finish
Chloride ions are the most aggressive environmental hazard when assessing the pitting corrosion risk. Marine
sites tend to be the most aggressive and so give the lowest projected durability.
Acid conditions, sometimes found in industrialised atmospheres, are also aggressive.
It is also important to consider the effects of local ‘micro climates’ that may influence how aggressive the
environment is.

Estimated pit penetration times

The pitting life predictions shown in the table are based on a linear pit growth rate model.

The marine and rural site samples had ‘mill’ finishes and the semi-industrial site results had dull polished
finishes.
The 1mm perforation times for the 304 (1.4301) type are consistent with the projected design lives of most
buildings.
It should be noted that the ferritic 430 (1.4016) type is not normally considered for building exterior
applications in the UK, but is included in the table for comparison.

Specifying coloured stainless steel finishes and their applications

Introduction

Stainless steel can be coloured either by the application of paint or by chemical treatments. Both are durable
in normal service, but damage can be difficult to repair, especially for finishes produced by chemical
treatment. Paint systems rely upon introducing a second layer of material onto the surface of the stainless
steel whereas chemical systems rely upon altering the thickness and nature of the passive film.
This article describes the specification and applications for chemically coloured stainless steel flat products.
The source of much of the information in this article is:
Colouring Stainless Steel by Euro Inox.

Producing chemically coloured finishes on stainless steel

Colouring of stainless steel is normally restricted to sheet products, and although it is possible to colour
fabricated components. Only the finest quality stainless steel sheet can be successfully chemically coloured
on a production basis.
Chemical colouring of stainless steel sheet uses a mixture of chromic and sulphuric acids that develop the
thickness of the naturally occurring passive film on the steel surface, depending on the immersion time. It is
a two stage immersion process that requires close control on the operation’s parameters and a considerable
operator skill to get the required colour consistency. A far less frequently produced ‘blackened’ finish can be
done by immersion on a fused sodium dichromate salt bath at around 400 C. This will not be discussed
further in this article.
The colours produced are the result of light wave interference effects in as light is reflected from the surface
of the thickened oxide passive layer and interface of the passive layer and steel surface. The sequence of
colours formed as the film grows in thickness ranges through bronze, blue, black, charcoal, gold, red-violet
and green. With care, intermediate colours are possible. The finished thickness of the passive film ranges
from 0.02 microns to produce a bronze colour effect to 0.36 microns to produce a green colour effect.
between the passive layer and the steel surface of the sheet.
The range of colours commercially available on austenitic 1.4301 (304) and 1.4401 (316) grades includes blue,
black, bronze, gold, green and red/violet. A charcoal colour effect can be produced by treating a satin
polished sheet to the same conditions that normally produce a blue on non-polished sheet surfaces.
The range of colours possible on ferritic grade 1.4016 (430) material is generally more restricted.
A wide range of pre-finished surfaces can be coloured. These include flat mechanically ground,
polished (satin) or blasted finishes or roll-patterned surfaces. Colouring can also be combined with acid
etched patterns to provide an even wider range of textures, lusters and reflectivity effects.

Comparison with anodized, painted and oxidized surfaces

Unlike anodizing, as used widely on aluminium products, the process is not an electrochemical one and in
contrast to painting, there are no pigments or colouring chemicals used. Perhaps more important the
process does not rely on heat to oxidize the surface, like the temper colours on heating at temperatures
between 300 and 600 C. In contrast to these oxidized surfaces, chemically coloured stainless steel retains
the aqueous (atmospheric) corrosion resistance of the un-coloured surface.

Surface Blackening

This is a chemical process involving the use of molten sodium dichromate. Immersion time controls the
degree of “blackness” achieved. The oxide film thus formed is quite adherent, allowing reasonable formability.

PVD Coatings (Physical Vapour Deposition)

This involves depositing a very thin layer of ceramic material (typically 0.3 micron). This allows the substrate
texture to show through. A range of colours is possible with this process - gold, bronze, blue, black and red.

Specifying coloured stainless steel products

Table 6 of BS EN 10088-2 uses special finish 2L for coloured flat products. This restricts the starting material
to cold rolled only (hot rolled finishes are not suitable for a good standard of coloured finish) and only one
side is required to meet the agreed colour tone and surface quality. The standard does not specify specific
colours. This is to be agreed between the specifier and the supplier.
Suppliers of these finished sheet products produce handy swatch samples to aide the finish selection process.

Applications for coloured stainless steel sheets

A particular attraction of chemically coloured stainless steel is that it appears to change colour under
different shades and angles of artificial and natural light. It is important, however to ensure that a good
match is achieved between sheets intended for multiple panel features.
Applications for these coloured sheets and panels include architectural external cladding (facades, columns,
roofing etc.), internal cladding in low traffic areas, signs, shop display panels, sculptures etc.
Coloured stainless steel is difficult to repair if scratched which is why it is best suited to these
applications where scratches and abrasion are relatively unlikely. Cold forming of coloured sheet during
fabrication is feasible however, provided the surfaces are suitably protected from scratch damage.
Joining by heat process, including welding is not advisable as changes to the original colour are very
difficult to repair or blend-in. Joining by cold processes such as adhesive bonding and mechanical fixing
are however suitable.
It is important that the steel sheets are sourced from the same mill supplier and batch run to obtain
consistency of overall appearance.

Melting, Slab Casting and Grinding 

To make ferritic stainless steels, one needs iron and chromium, and to make austenitic stainless steels, nickel
is added to the mixture. This raw material mixture is melted in an electric arc furnace. The molten metal is
refined and decarburised in an Argon-Oxygen Decarburiser (AOD) vessel by blowing oxygen, argon and
nitrogen into the molten steel. The refined stainless steel is processed through a continuous casting
machine to produce stainless steel slabs. The slabs can go through a surface grinding process to remove
any possible surface defects.The slabs are typically between 900mm and 1 600mm wide, 200mm thick,
and can be cut to lengths of between 4 and 12m.

Hot Rolling

The hot rolling process begins at the reheat furnace where the slabs are heated to between 1 100 and 1 300°C,
depending on the stainless steel grade. The slabs are then rolled on a reversing four high mill to gauges
between 65 and 25mm. Thinner gauges are rolled down further on the Steckel mill. Once the predetermined
gauge is reached, the material can either be coiled (black coil, also known as hot band, HR or HRA) or cut into
plate (black plate (HRA)).
Coil mass is between 20 and 30 tons and the thickness is generally between 3mm and 8mm.
Plate thickness can range between 3 mm and 65 mm.

Annealing and Pickling 

The hot rolled products are softened (annealed) and descaled (pickled with acids) to produce a No. 1 finish
product. This product has a light grey matt surface finish.

Cold Rolling and Finishing 

Cold rolling of the No. 1 coils takes place on Sendzimer mills (Z-mills), which produce smooth, shiny
finished, cold rolled stainless steel.
The thickness range of the cold rolled product is between 0,2mm and 6mm.
The material is then annealed (softened) and pickled (and passivated), before it is processed through the
skinpass mill, to ensure a smooth surface, known as a 2B finish.
Alternatively, the cold rolled material can be processed to a bright annealed (BA) finish. This is achieved
by annealing in a vertical furnace with an inert atmosphere, to retain the bright surface imparted by the
cold rolling process.
These cold rolled stainless steel coils can then be cut into smaller coils or sheets, or slit to narrower
widths before being packed and shipped.

Polishing 

Following the cold rolling, annealing and skin passing processes, a material can be given a uniform scratch
finish by polishing with abrasive belts.