Poland’s largest anodising plant of aluminium products

Anodising plant of aluminium products is part of ROSA GROUP since 2009. Currently it is the largest of this kind facility in Europe. Its launch has allowed Rosa company to introduce to the lighting market an unrivaled, comprehensive range of aluminum outdoor lighting products with anti-corrosive and decorative qualities.

ROSA anodising plant specializes in services such as anodising electrochemical or interference colouring of aluminium materials - shets, pipes, profiles or other structural elements, in 10 anodising colours, each withpossibility of chemical brightening. Modern interference technology of colouring provides richer from the traditional colour palette, resistant to external factors, including UV radiation.

10 unique anodising colours

Criteria for anodised elements

  • Both simple and complicated shapes
  • Maximum length: 10 meters
  • Width: 0.55 meter
  • Max height: 2.30 meters
  • Unit weight: up to 500kg
    (Total weight for a single batch is up to 1.5 t)
  • Max dimensions of shot blasting elements: height 0.45m, width 0.7m, length 10m

Technical approvals. Highest quality.

Technical Approval of the European Association of Aluminum Surface Treatment QUALANOD with the right to use the mark QUALANOD quality of anodic coatings – It confirm the highest quality of services provided by Anodizing Plant ROSA.

Anodizing process

The anode process can be divided into three basic stages:

  1. Surface preparation by degreasing, satin etching or glazing, brightening;
  2. Anodizing + optional staining;
  3. sealing.

These operations are carried out  in special baths and each process requires separate. Between the essential processes the rinsing operation of the product is performed.

The first step in surface preparation is degreasing- - removal of grease and other contaminants of various origin from the surface of the aluminium. The surface thus cleansed is subjected to digestion- alkaline bath phase – removal of oxide layer from product surface, giving it a matt finish and to compensate for minor defects after stamping or rolling, such as streaks, thermal belts and delicate scratches. The alternative finish of satin surfaces is chemical brightening. By acidifying a mixture of concentrated acids, the surface structure is smoothed out, which significantly reduces matting and brightens the surface of the metal and results in a glossy finish.

Next process of preparing the surfaces for anodising is lightening (pickling) –finally remove the thin oxide layers and deposits that may have remained after satin etching or lightening, and which removal is necessary to achieve a uniformly structured oxide coating.

Anodising is the electrochemical formation of aluminium oxide on the surface of aluminium. This coating is made in aqueous sulfuric acid, and the anodised element performs an anode function in this process. During electrolysis, when oxygen is applied to the anode at a specific density, oxygen is released and reacting with the metal forming a transparent oxide coating. The coating thus formed grows in 2/3 of its thickness into the metal surface and grows 1/3 above it. It is much thicker than natural, so it effectively protects aluminium from further oxidation, i.e. corrosion. Its porous structure also allows for permanent colouring of the product by electrochemical or interference method with high UV resistance.

Electrochemical colouring is based on the treatment of the anodised product in the electrolyte containing tin ions. Reduced in a cathode cycle metal is de-posited on the bottom of the pores of the oxide coating and gives a permanent colouring to the aluminium surface. This results in a range of colours from bright to dark shades of brown and black. Interference colouring is preceded by pore shape modification operation of the anodic layer. At this stage, the structure of the lower part of the porous layer is changed by giving it a spherical shape. Such modified layer is subjected to an electrochemical colouring, in tin-based baths, widening the colour palette of electrochemical colours with gray and green shades. This method uses the phenomenon of interference, that is, the overlapping of reflected light waves, leading to the increase or decrease of the amplitude of the incident wave. Modifying this amplitude through the appropriate controlled variation of the pore shape of the anode layer allows for an appropriate optical effect (colour).

The last step in anodised technology is sealing consisting of closing the porous oxide layer. The medium temperature seal (86-88 °C) is used to immerse the product in hot demineralized water with accelerating additives to fill the pores of oxide layer with boehmite. Thanks to sealing, the anodised surface becomes sealed and smooth, which makes the oxide coating resistant to atmospheric corrosion and reduces the tendency for sedimentation on the product surface.

Proper maintenance and regular cleaning of anodised aluminium products keep their aesthetic and decorative appearance for longer. From 2017 the plant also uses technology so-called dry etching involves surface treatment by shot blasting method. The process is carried out using a modern machine to matt the surface by subjecting the workpieces to abrasive blasting operations using shot with a diameter of about 0,1 mm, giving the surfaces a delicate, satin appearance. This type of technology allows to significantly eliminate all kinds of surface defects arising from extrusion or rolling processes such as streaks, thermal lines, etc. and minor mechanical damages in the form of scratches and abrasions. The surfaces thus obtained are characterized by much better quality compared to traditional chemical etching. Used technical solutions allow to shot blast elements from sheet thickness of 1mm without the risk of surface damage.

Research

UV resistance**

 - utest device: Q-Sun Xe-3

-  sample exposure time: 14 600 h

-  exposure time equivalent for Polish climatic conditions - 20 years*

-  test result: no colour changes of oxide coatings

* the study was carried out in the ROSA Research and Development Laboratory in accordance with PN-EN ISO 6581 "Anodic Oxidation of Aluminium and Its Alloys - Determination of relative resistance of anodised oxied coatings against UV light and high temperature".

Corrosion resistance**

- test device: salt chamber with salt concentration of 5%

Concentration of salt in the Baltic Sea - 0.8%

Concentration of salt in the North Sea - 3%

Samples exposure time - 20 000h

Test results: No evidence of corrosion was observed in 20 000 exposure hours

** The test was carried out in the ROSA Research and Development Laboratory according to the PN EN ISO 9227 standard, using the NSS method.

Cleaning and maintenance

What is the cleaning and maintenance of aluminum lighting columns?

In general, anodised surfaces are highly resistant to contamination, but maintenance of high decorative surfaces of the columns may require periodic cleaning. Why? Some types of pollutants, due to their properties, can permanently fall on the surface of the column, thus impairing the decorative qualities. In case of columns, these are often pollutants typical of highly industrialized areas: substances used in the operation of roads, industrial plants, etc. The frequency of cleaning and maintenance depends mainly on the user's decision. The vast majority of external factors are unable to negatively affect the quality and durability of the anodised surface.

Important! For cleaning and maintenance of anodised columns only cleaning products with neutral pH (5-9) should be used. What is more, do not use materials and objects that can scratch and damage the anodic coating. After removing the impurities, the surface must be rinsed thoroughly with clean water to completely remove the residue of cleaning substances.

Example of cleaning and maintenance of anodised columns using traditional cleaning and maintenance products for aluminum anodised surfaces.

In  case of extremely difficult to remove solid, permanent precipitates often formed by the crystallization of salt compounds, it is recommended to use specially dedicated products, for example, for removal of heating stones from an installation made of aluminum. These products effectively dissolve all types of sediments without damaging the top anodic layer. An example of such application could be the removal of salt sediment from the seawater-fed water system after the desalination process from the surface of an anodised column installed in Saudi Arabia. This kind of water in its composition contains lots of mineral compounds. Because of high ambient temperatures, water rapidly evaporates, leaving a solid sediment on the column surface. The picture below shows the anodised column construction before and after cleaning with Calnex C.

For removing all types of paints, adhesives, graffiti and other residues of this type of substances, it is best to use products  for paint coatings removal.  A wide range of solvents such as acetone, nitro or alcohol based solvents are available on the market, which effectively dissolve these impurities while remaining safe for the surface of the column.

Above example of column cleaning from graffiti and glue leftovers from stickers. By using generally available products for removing such contaminants, any dirt has been effectively removed without interfering with the anodic coating. After cleaning there is no any difference on the surface of the column.

Anodising is second to none.Benefits of using anodised aluminium columns.

Among the various ways to protect aluminium, anodising is second to none. In addition to the superior protection against weather conditions, anodised aluminium also features exceptional decorative qualities. Among the many advantages of using anodised aluminium columns, we distinguish:

  • high aesthetics of the column throughout its life;
  • anodised coatings are integrally connected with the surface, so there is no possibility of peeling, spalling or delamination;
  • full protection throughout the life of the service;
  • high resistance to UV radiation,
  • high abrasion resistance due to greater hardness of the coating,
  • anode surfaces are free from corrosion,
  • availability of a wide range of colours dyed with electrochemical and interferential methods;
  • possibility to recycle the material (100% recyclable);
  • decorative surface function.

Architectural Panels - anodised facade of the University of Art in Poznan

This investment consisted in the revitalization and reconstruction of the existing buildings’ complex at intersection of Aleje Marcinkowskiego and 23rd February Street in the historic center of Poznan, close to the Old Market Square, Freedom Plaza and National Museum. New building “B” and Sculpture Pavilion with total area of ​​almost 6 thousand square meters has teaching and training halls and specialized studios. The indoor courtyard of building “B” covered with skylight is for organizing spatial exhibitions and multimedia activities.

The exterior facade panels and also the panels used as the ceilling was anodised in graphite colour with satin effect (without brightening). The total anodised panels of varying sizes in the case of the facade correspond to the total area of ​​almost 1 200 square meters and nearly 300 square meters of suspended ceilings. This project is an example of using the graphite anodising aluminum colour, which as one of the interference colours made in Poland only in the company ROSA.