Without surface treatment
Untreated steel fittings will rust immediately in a humid environment if they are not protected against corrosion.
Untreated brass fittings are naturally aged by the moisture and oxygen in the air and over time take on a darker color. Brass contains copper and will tarnish if exposed to excessive moisture. Brass fittings are not varnished.
Electro-galvanizing
It is carried out electrolytically. The zinc forms a layer of about 12 µm. 1 µm = 1/1000 mm. The surface layer of the zinc is chemically transformed into a passivation layer, which protects the zinc against corrosion. If a scratch occurs in the zinc layer, the surrounding zinc ”migrates” to the damaged area and protects it (”self-healing”). The zinc coating is slightly blue in color and is relatively shiny. Zinc is a fairly soft metal. Electric galvanizing replaced cadmium plating in the 1950s as a corrusion protection for steel parts.
Hot dip galvanizing
Performed by dipping in molten zinc. A subsequent centrifugation removes excess zinc and produces a matt, gray surface with a zinc thickness of 45-75 µm. The reaction of the zinc with the steel results in good adhesion. Minor damage to the zinc layer ”self-heals”.
Nickel plating
Performed electrolytically on both steel and brass. Gives a high gloss silver colored surface (slightly yellowish) when the surface is polished. On untreated surfaces, the nickel plating becomes rough depending on the nature of the surface, but is still silver in color. Layer thickness 10-15 µm. Nickel plating is a decorative surface treatment. The nickel layer always has micro-cracks that eventually let moisture into the base metal, which rusts (steel) or scars (brass).
It is not ”self-healing”. The nickel layer is inherently very hard, so scratches do not occur easily. Nickel plating came into use in the 1890s and quickly became popular, as it does not (like brass) need to be polished to keep it shiny. However, nickel plating eventually becomes matte.
Tinning
An electrolytic tinning of steel. Has excellent rust protective properties. Layer thickness 10-15 µm.
In the 18th century, various hand-forged fittings were tinned for outdoor use. It was the best rust protection at the time. It gives a semi-matte silver colored surface and is not ”self-healing”.
Gilding
Electrolytic gilding is performed on steel parts that have first been nickel-plated, to make steel look like brass. The gold layer is about 1µm thick. Used primarily for details that would be too weak if they were made of brass, such as hinges and accessories for espagnolettes. We do not apply protect paint to gilded details, but they will still retain their shine.
Gilding has no anti-corrosion properties but is purely decorative.
