Non Ferrous Metals Used for Interior Design Finishes
Types of Metal for Interiors – Non Ferrous Metals
Types of non ferrous metals included here are Copper, Nickel, Tin, Cadmium, Zinc, Aluminium and Lead. Precious metals are excluded as the likes of silver and gold are usually reserved for art works or plating.
Copper
Copper is a pink or salmon red colour when polished. It is a reasonably soft metal and is both malleable and ductile. Copper has until the invention of the fiberoptic cable been almost extensively used for the lines for the telecommunication industry. When left to oxidise it turns a soft green colour or patina. As designers both of theses colours are desirable for either the bright or rustic finish.
We as designers use copper for effect with timber trim, as bench tops or splashbacks, and very often for ornamental work, roofing and spouting. It is also used for table tops and as a colour to fixings such as dome studs to a table. Copper does have a drawback however as it has to be kept polished to retain the bright effect unless treated with perhaps a lacquer. When used as a bench top beware as it will react with ammonia and needs to be polished often unless you are happy with the patina look. Copper when mixed with zinc or tin produces alloys such as Brass or Bronze respectively.
Copper and Zinc = Brass (Golden colour)
Copper and Tin = Bronze (Brown colour)
Brass
Brass, like most metals, comes in various grades including gilding and cartridge brass. Brass is classified according to its Zinc content. Because brasses are resistant to corrosion we see them used a lot in situations where they are exposed to the elements and in particular the sea. Ship’s brass is a particular type of brass and is particularly resistant to the salt water however it will still corrode which is why we see the polishing and maintenance of fittings on ships and yachts. Designers use brass for effect on trim such as light fittings, screws, and especially as good quality hardware for cabinetry and doors.
Bronze
Bronze is the alloy produced when tin is mixed with copper. It is very fluid when molten and that is one of the reasons that it is used for castings. (Being fluid allows the metal to flow into small details). Hence we see it on intricate work such as busts or other artwork. Designers often use it for ornate nameplates and also hardware.
Gunmetal
Gunmetal is another alloy produced from tin bronze and zinc. It is very resistant to corrosion while being relatively strong. This is not used a great deal nowadays but was originally used for weapons because of these properties. Newer metals have superseded it in its traditional roles.
Tin
Tin is an expensive metal that is soft and weak, but has a high resistance to corrosion. It is used for plating steel sheet and as already mentioned is used as part of the alloy Bronze.
Nickel
Nickel is another metal used for plating ferrous metals. It is white and hard and can be highly polished. You will often see nickel plated items as an alternative to chrome plated.
Chromium
Chromium is also very resistant to corrosion and is also used to coat ferrous metals as it resists corrosion and is also very hard. We see it used for plating various furniture and joinery hardware items as well as door furniture because of its bright appearance and resistance to abrasion.
Zinc
Zinc is another metal used for plating ferrous metals as it has good anti corrosive properties. Zinc is initially a bright metal, which tarnishes to a soft grey. We commonly see it coating old roofing iron, commonly known as galvanised iron. The coating is not a pristine finish and zinc will often been used as the undercoat to another more aesthetic finish such as a paint system or powder coating. You will hear the term hot dip galvanising used by engineers and specifiers to ensure that the base metal, usually steel is given a corrosion inhibiting coat.
Lead
Lead is a soft dark grey metal. When it is freshly cut the cut edge will look shiny but quickly tarnishes in air. It oxidises (the metal reacts with the oxygen in the air) and forms an oxide as a coating. Lead used to be used extensively in buildings for drainage and flashings on the outsides of building openings and penetrations in iron rooves. This was because it is soft and malleable and could be formed around difficult shapes easily. Today these flashings are more often made of coated aluminium to windows and doors or flexible compound type gaskets to the roof penetrations. However there is one very important use that lead has especially for designers. Because it is so dense it is often used as a weight to the bases of drapes or curtains. As lead is soft it doesn’t have much abrasion on the material. We will also use lead as a filling weight to table bases or candelabra or lamps and it is still used on a daily basis in lead light windows. It has many industrial uses too.
Aluminium
Aluminium would be one of the most used metals in the building industry today. From roof cladding, window and door joinery, to furniture, framing and entire components. It is semi soft and dull grey but can be highly polished. It is available in sheet form and can be used as a decorative cladding (perforations and embossing as well as items such as chair seats entire chairs and table tops. It is not recommended for items such as benches as it does scratch reasonably easily and reacts with some chemicals such as bleach, strong detergents and soda. It is also used to form a number of alloys.
Aluminium can be protected by a process called anodising. This is an electrochemical process and forms a coating, which is integral but harder than the base metal. Aluminium should not be allowed to have cement or lime left on it (such as on a building site) as it will adhere to the metal and when removed stain and or scratch the surface. Because of this aluminium on a building site should be left with its protective coating on it (such as plastic) until all wet work is complete.
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