A bar of aluminium caused a real stir at the 1855 World Exhibition in Paris. This ‘silver out of clay’ was feted like a priceless rarity. We now know that, after oxygen and silicon, aluminium is the third most common element in the Earth’s crust.

Aluminium is won from a red sedimentary rock first discovered at Les Baux in France and thenceforth known as bauxite ore. It is a light metal (with a density of 2.699 g/cm3) that melts at approx. 660° Centigrade. Its natural colour is a silvery white. Aluminium can be cast or rolled into virtually any shape, including very fine foil.
When aluminium is first extracted, it has to be said that rather a lot of energy is consumed. But this initially negative energy record is more than made up for by the positive properties displayed by the material when it is worked, used and, above all, recycled.

Almost 95 per cent less energy is used at the reprocessing stage than during the initial extraction process. And the wonder of aluminium is that it can be reprocessed over and over again without any of it being lost. This lightweight amongst metals is pleasant to the touch, primarily because it is particularly good at adapting to environmental temperatures. FSB exclusively works pure alloys as per the German standard DIN 1725 having the following material numbers:

• AlMg3: Mat. No. 3.3541.02
• AlMg1: Mat. No. 3.3315
• AlMgSi0,5: Mat. No. 3.3206

Once the surface has been machined, it is protected by an electrochemical process of anodisation that transforms the aluminium surface into aluminium oxide to a certain depth.

FSB adopts the standard direct-current sulphuric acid electrolyte method for its anodising operations. The oxide layer created with this standard method is approx. 10 μm thick and has a hardness of up to 350 kp/mm2 (Vickers), the equivalent of 2,500-3,500 N/mm2. The silvery white oxide layer can be colour-stained, thus extending the range of design options available. FSB performs two types of colour-staining:

1. Staining of the surface and in the centre of the oxide layer
by dipping, also referred to as the absorption method. This involves chemically immersing the initially silvery white anodised aluminium in organic and inorganic dye solutions and yields a colour fastness rating of between 6 and 7.

2. Staining at the base of the pores of the oxide layer. Here, alternating current is used to intercalate metals in the silvery white oxide layer previously generated by electrolytic means. This is referred to as a two-stage method and yields colour fastness ratings of between 7 and 8.

Once the surface has been colour-stained it is compacted. This ensures the stain is resistant against corrosion, light and the elements to the degree indicated in the values cited. Aluminium essentially requires no looking after. It is protected by an anodised layer created by either natural or artificial means. Dirt marks can be removed with water and a soft cloth.