Coatings

Anodising of aluminium

Use/properties

An electrochemical surface treatment process for aluminium products that forms an oxide layer on the surface of the product, giving the aluminium good corrosion resistance, a nice appearance, and various other properties, such as hardness and wear resistance.

The main factors that affect the appearance of the oxide layer are the surface quality of the raw material, and the quality and purity of the aluminium used.

Treatments

Anodising is performed in a sulphuric acid solution. The oxide layer that forms on the surface of the product can be natural in colour or can be dyed black.

The aluminium surface can also first be chemically or mechanically polished and then anodised, in a process called bright anodising. In bright anodising, the oxide layer that forms on the surface of the product is glossy, giving the product a decorative appearance.

Standard

ISO 7599:2010(E) Anodizing of aluminium and its alloys — General specifications for anodic oxidation coatings on aluminium

Bright anodising of aluminium

The process of polishing aluminium is based on using chemicals to aggressively attack the aluminum surface, which levels the microscopic roughness of the surface, making it glossy.

The polishing process can be used either alone or in combination with an anodising process. The combined process produces an even, glossy anodised oxide layer, which gives aluminium parts good corrosion resistance, a pleasant, glossy appearance, hardness, and abrasion resistance.

The chemical polishing process is suitable for many types of aluminium, including ones that contain magnesium. However, the best and highest gloss is achieved on pure aluminium.

Bright chrome plating

Use/properties

An electrochemical electrolytic process that deposits an even, glossy, easily spreadable, and beautiful bluish chrome coating on products. In reaction with air, an oxide layer forms on the chrome surface, which becomes passivated, providing protection against corrosion.

A process known as "decorative chrome plating" always uses a nickel coating as a primer under the chrome, and, if necessary, there can be several layers of coating under the chrome, to provide products with additional properties.

A bright chrome plate is used to provide products with decorative properties such as gloss, evenness, or a specific colour, and properties such as hardness, wear resistance[M2] , and excellent corrosion protection.

Standard

SFS-EN ISO 1456 Metallic and other inorganic coatings. Electrodeposited coatings of nickel, nickel plus chromium, copper plus nickel and of copper plus nickel plus chromium (ISO 1456:2009)

Chromate conversion coating of aluminium

Use/properties

A chemical surface treatment process that involves a reaction between the aluminium surface and a solution, forming a chromate coating on the surface. The colour of the chromate coating can vary from almost colourless to pale yellow and yellowish-brown; the darker the colour, the thicker the chromate coating.

The purpose of the chromate coating is to provide products with better corrosion resistance, to prevent changes in contact resistance, and to serve as a good adhesive base for paints.

Chromate solutions often contain hexavalent chromium compounds in the form of chromic acid or dichromates.

You can choose between a rack or barrel coating method.

Standard

SFS-EN 12487 Metallien korroosionesto. Alumiinin ja alumiiniseosten huuhdellut ja huuhtelemattomat kromatointipinnoitteet. Corrosion protection of metals. Rinsed and non-rinsed chromate conversion coatings on aluminium and aluminium alloys

Copper plating

Use/properties

An electrochemical electrolytic process that deposits a high-gloss, non-porous, and easily spreadable copper coating on products. The deposited copper surface is soft and highly malleable.

A copper coating is often used as an intermediate coating between other coatings, to provide additional properties for products, such as a good covering power, good base adhesion, and additional corrosion protection.

The process can be used to coat steel, aluminium, copper alloy and zinc die-cast[M1] objects.

You can choose between a rack or barrel coating method.

Standard

No standard in force (SFS-EN ISO 1456). [M1]Sinkkipainevalu? Joko näin tai mahdollisesti 'zinc pressure- cast'?

Nickel plating (+ semi-gloss nickel)

Use/properties

An electrochemical electrolytic process that deposits a high-gloss and highly spreadable and smoothable nickel coating on products. The deposited nickel surface always has a slightly yellowish colour. The nickel coating is extremely soft and free from internal stress. The process is also ideal for double nickel plating (in which the first layer is semi-gloss nickel and the second layer is high-gloss nickel), which provides products with especially good corrosion protection performance, including in outdoor conditions.

Nickel coating is used to provide products with decorative properties, such as gloss, evenness, or a specific colour, and properties such as hardness, wear resistance, and excellent corrosion protection. A nickel coating is also used as a primer in bright chrome plating. If necessary, there can be several layers of coating under the nickel, to provide products with additional properties.

You can choose between a rack or barrel coating method.

Standard

SFS-EN ISO 1456 Metallic and other inorganic coatings. Electrodeposited coatings of nickel, nickel plus chromium, copper plus nickel and of copper plus nickel plus chromium (ISO 1456:2009)

Passivation of aluminium (Iridite NCP)

Use/properties

A chemical surface treatment process that involves a reaction between the aluminium surface and a solution, forming a passivation layer on the surface. The passivation layer is almost colourless, although it shows faint iridescence in different colours.

The purpose of the passivation layer is to provide good corrosion resistance for products, and a thermal resistance of 350°C without compromising corrosion resistance performance, and to serve as a good adhesive base for paints.

The passivation layer does not contain lead, cadmium, mercury, PBB/PBDE, or chromium (III) or (VI) compounds, and complies with the ELV, RoHS and WEEE directives.

Standard

No standard in force

Passivation of copper and silver

Use/properties

A passivated surface is completely clear and even, and the gloss of the original surface is not affected. The passivation layer effectively protects the surface against oxidation, and does not contain any chromates. The passivated surface performs superbly in a sulphide-containing environment (30 minutes, 2% sodium sulphide).

Pickling of stainless steel

Use/properties

Pickling of stainless steel cleans all the surface impurities, such as scale, discolouration and rust on welding joints. Pickling creates a passivation layer (an oxide film) on the surface that provides corrosion protection.

Pickling gives the stainless steel a metallic and silky matt surface.

Standard

No standard in force.

Silver plating (+ passivation)

Use/properties

An electrochemical electrolytic process that deposits an even, glossy silver coating on products. Silver plating is used to provide products with properties such as electrical and thermal conductivity, hardness, and wear resistance, and to provide objects, especially utility items, with decorative properties. The process can be used to coat steel, copper and copper alloys, and nickel-plated objects.

You can choose between a rack or barrel coating method.

Finishing treatments (passivation)

A silver coating tarnishes with age, and, to stop this natural reaction, silver-plated products are often protected through passivation. The passivation layer is completely clear, which means it does not affect the gloss of the original surface or the other properties achieved by silver plating.

Standard

SFS-EN ISO 4521 Metalliset ja muut epäorgaaniset pinnoitteet. Sähkösaostetut hopea- ja hopeaseospinnoitteet teknisiin tarkoituksiin. Spesifikaatio ja testausmenetelmät. Metallic and other inorganic coatings. Electrodeposited silver and silver alloy coatings for engineering purposes. Specification and test methods (ISO 4521:2008)

Tin plating

Use/properties

An electrochemical electrolytic process that deposits a high-gloss and highly spreadable tin surface on products, with an extremely even coating thickness.

The deposited tin coating has excellent solderability and adhesion, and it also has excellent annealing resistance.

Tin plating is ideal for use in decorative and technical coatings, for example in the electrical and electronics industries and in the production of household goods.

You can choose between a rack or barrel coating method.

Standard

SFS-ISO 2093 Sähkösaostetut tinapinnoitteet. Määrittely ja testausmenetelmät. Electroplated coatings of tin. Specification and test methods

Zinc-electroplating

Use/properties

An electrochemical electrolytic process that deposits a high-gloss zinc coating with excellent covering power and spreadability. Without a chromate finish, the deposited zinc surface has a silver grey colour. The deposited zinc coating is also extremely flexible and is easy to chromate (passivation).

Zinc coating is used to provide products with decorative properties such as gloss, smoothness, or a specific colour, and to act as a base for paint and to provide good corrosion protection.

Normally, all zinc-electroplated surfaces are chromated immediately afterwards as part of the coating process, in order to prevent the formation of what is known as white rust on the zinc surface.

You can choose between a rack or barrel coating method.

Chromating (passivation)

A conversion coating layer formed on a zinc surface that protects the zinc surface from the formation of corrosion.

Conversion coating gives the zinc surface a particular colour, depending on the type of chromating used:

  • blue,
  • yellow (iridescent),
  • green,
  • black or
  • silver (iridescent).

Blue passivation

A passivation bath for zinc coatings that produces a high-gloss and deep blue passivation layer. Only trivalent chromium compounds are used. The gloss, colour and corrosion protection are also preserved in heat-treated objects. Passivation produces a white rust resistance of more than 100 hours for rack-coated objects in a salt-spray test, conducted in accordance with the DIN 50021 SS standard. The corrosion resistance is also retained after heat treatment.

Cr6+ yellow passivation

A passivation bath for zinc coatings that produces a yellow iridescent Cr6+ chromate layer. Passivation can produce extremely good corrosion protection. A resistance of more than 500 hours has been achieved in salt-spray tests. Under normal conditions, we can easily achieve a white rust resistance of 300 hours for rack-coated objects, and a resistance of 250 hours for barrel-coated objects.

Cr3+ yellow passivation

A yellow passivation process for zinc coatings that uses trivalent chromium and produces good corrosion protection. The passivated surface has a yellow iridescent colour, which becomes slightly lighter but more even after a finishing treatment. Cr3+ passivation can produce corrosion protection that is almost the same as in hexavalent yellow passivation. The gloss, colour, and corrosion resistance of the passivated surface are retained even after heat treatment.

Green passivation

A Cr6+ passivation bath for zinc coatings. The chromate layer produces a dark olive-green film on products and provides excellent corrosion protection, comparable to that achieved with Cr6+ yellow passivation.

Black passivation

A Cr6+ passivation bath for zinc coatings. The chromate layer produces a glossy black film on the zinc surface and provides relatively poor corrosion protection.

Lanthane TR 175 special passivation

A passivation system for zinc coatings that is based on the use of trivalent chromium and nanoparticles. The chromate layer produces a bright, silvery iridescent film on products and provides excellent corrosion protection, due to the nanoparticle technology used.

Sealing

Sealing is a finishing dip for zinc-coated and passivated surfaces. The sealer protects the passivation layer against the various environmental and weather effects, giving the zinc-coated and passivated surface additional protection against corrosion and mechanical stress. The finishing dip is based on active corrosion protection, in which polysilicates, polymers and inhibitors work together to protect the zinc from corrosion, and it also provides ready-made products with self-protective properties that, for example, prevent corrosion in the event of scratches or dents.

Varnishing

A colourless, water-thinnable, drying oven varnish for zinc-coated and passivated surfaces. The varnish is widely used to protect decorative surfaces: to provide additional protection against corrosion and to prevent subsequent colour changes in the coating.

Standard

SFS-EN ISO 2081 Metalliset ja muut epäorgaaniset pinnoitteet. Raudan tai teräksen sähkösaostetut sinkkipinnoitteet lisäkäsittelyineen. Metallic and other inorganic coatings. Electroplated coatings of zinc with supplementary treatments on iron or steel