ALUMAL cleaners and surface preparation technologies are available in both liquid and powder products designed for removal of a range of contaminants from cast and wrought alloys including water soluble lubricants, and other types of oils and buffing or polishing pastes.

They are designed to remove contaminants and soils from machined and non-machined aluminium surfaces and are easily rinsed from part or component surfaces. The product range is designed and specifically formulated chemical blends consisting of salts, surface active wetting agents to provide detergency, and in some formulations, sequestrant (mild chelating) agents which are utilized to help stop formation of scales on tanks and equipment to provide long life and extended performance from the cleaner. Many uses are applied by immersion processing, but also formulations are available for spray processing. ALUMAL Cleaners are available as non-etch, mild-etch, and etch formulations both from acid and alkaline chemistries. These options offer a wide range of operation on all types of aluminium alloys.

• The Non-Etch Cleaners were designed for the removal of surface soils before any etching process. This approach will maintain aluminium surface finish integrity so the actual etching process is more efficient and provides uniform surface aspect.

• The Etch-Cleaners are perfect for cases when installation of a separate non-etch cleaner followed by an etch tank is not possible due to space limitations. Etch cleaners are formulated to carry out both processes depending on the application. Etch cleaning always requires proper surface desmutting to remove alloy smuts that result from etching process.

For certain applications and aluminium alloys, the surface etching can enhance the final finish of the part or component by providing a given aspect (matte, satin, etc.) Etching is also important to help conceal surface defects such as die lines, scratches or in mixed alloy aluminium components, the etching process gives a uniform surface appearance.
Etching can be accomplished with both Acid or Caustic systems. Each ALUMAL type are blended with special surfactants to minimize fuming, or to provide a foam blanket, and the chemistries contain anti-scaling agents to keep the tank, heating equipment and other process equipment working at optimum for high throughput. Alkaline type etch systems will dissolve more aluminium and leave behind typically more smut. Acid etch type systems tend to smut less because they dissolve both aluminium and alloy constituents at more of an equal rate. In both cases, ALUMAL Deoxidizing / Desmutting chemistries are designed to provide the proper surface conditions for subsequent processing.

Sometimes Etch systems and Etch cleaners require some modifications to enhance their performance. The following products are available and when added to ALUMAL Cleaners, ETCH-Cleaners or ETCHES as required, they improve system performance.

ALUMAL ETCH 214 – Liquid, immersion, addition agent for alkaline cleaners and alkaline etching systems to minimize the precipitation of alumina for extending the solution life. Also used in rack/jig stripping applications.

ALUMAL ETCH AB 212 – Liquid, immersion or spray, addition agent blend of surfactants to improve cleaning efficiency of alkaline etching or alkaline etch clean systems.

ALUMAL ETCH AB 213 – Liquid, immersion or spray, addition agent blend of surfactants and complexing agents to improve cleaning efficiency and stability of alkaline etching systems. For use with caustic soda.

ALUMAL ETCH AB 220 – Liquid, immersion, Surfactant system to provide foam blanket to reduce caustic soda fumes from alkaline etching systems, rack stripping solutions and anodizing solutions.

The primary function of chemical or electropolishing (electrolytic) brightening is to improve aluminium surface smoothness and increase the luminous reflectance of the surface. These processes also help to remove some substrate defects such as die lines, flow lines and mild scratches in some parts/components/alloys.

ALUMAL BRIGHT systems work by dissolving preferentially micro-protrusions on the metal surfaces without forming etch patterns that are visible. When aluminium is dissolved chemically or anodically, these chemical or electrolytic treatments dissolve the oxidation layer as quickly as it reforms due to the active surface. As a result, after brightening treatments, the process sequence must use a deoxidizer prior to any conversion coating, anodizing process or plating process.

Aluminium has a natural protective oxide surface film and affinity for oxygen, in order to improve the appearance of an aluminium part or component through conversion coating, painting, anodizing or plating processes, requires some additional surface treatment processing to remove the natural oxide layer.

Once aluminium and alloys are exposed to etching solutions, the oxides are often removed but then depending on the alloy of aluminium, there are surface adherent non-reactive reaction products referred to as “smuts” on their surfaces. Desmut formulations are required to remove these from the surfaces of aluminium parts or components. The types of smuts present are related to the alloy of aluminium. For example, 200 series wrought aluminium have resulting copper smuts that are effectively removed by iron based desmut formulations. Alloys containing silicon or magnesium smuts are thoroughly desmutted with blends of acids including fluorides, nitrates & sulphates. All surface smuts must be removed for success with applications of conversion coatings, painting, anodizing or plating aluminium and alloys. Choices for Anodizing applications include ALUMAL DEOX 411, 436 or 444. For chemical conversion coating prior to painting, review ALUMAL DEOX 411, 425, 445, or 427.

Anodizing aluminium and alloys is an important electrolytic passivation process utilized across many industries to increase the performance of parts fabricated from alloys of aluminium or to improve the appearance of their surfaces.

In many markets and for a multitude of applications where aluminium and alloys are utilized including the architectural, automotive, aircraft/aerospace industries, colours of many types of parts and surfaces provide an important visual or aesthetic appeal.

Electro-Colouring 800 Series – Provides a very stable, long lasting colour option to anodized aluminium layers for very demanding applications. The process is an electrolytic process post anodizing that deposits metals into the pores of the anodize surface. The resulting colour is dependent on the type and amount of metal deposited. Nickel based chemistries produce stainless steel shades to lighter bronze colours. Tin based systems are designed for darker ranges of colour applications and copper based provide light pink to red colours. COVENTYA offers several ALUMAL Colour options including the following.

Because of the porous structure obtained in commercial sulfuric acid anodizing, the pores require sealing to optimize performance of the layer, including corrosion resistance and dye colour intensity, colour stability and fade resistance. Sealing of anodized layers is simply filling up the pores with some type of larger molecule, and converting the inside of the pore to a hydrated aluminium oxide which closes/plugs the pore.

There are different types of seals that all offer various levels of corrosion performance and dye absorption/stability. ALUMAL Cold Seal technology provides the maximum protection qualities and corrosion resistance for sulfuric anodized coatings. The oxide layer benefits from the sealing process after formation or after colouring. This specific type of hydration of the oxide pores helps with stain and corrosion resistance. Due to higher energy costs of higher temperature sealing, 75-85 OC for mid temperature and 100 OC for traditional hot seals, the cold sealing at room temperature is favoured and allows all the proper chemical reactions to take place for improving anodize layer performance. Sealing at room temperature also helps better stability of colouring or dye processing and offers improved colour fade resistance over conventional high temperature or mid temperature sealing processes.