All Metal  Solutions were approached by Martin Haswell Furniture to manufacture and supply steel components for the new Ralph Lauren in-store facility on the 5th floor of Harrods in Knightsbridge.  We only had 3 weeks to complete the job and there was an unusual finish required to the surface of the following components:-

• Under Shelf Hanging Rails 
• Full Size mobile hanging rails
• Shelf support Brackets
• Handrails to the stair well entrance

This unusual finish to all these steel components  uses a process called Black Oxide or “Blackening” which is a method normally used on machine screws as it give a minimal thickness build up to the surface .
Black oxide or blackening

This is a conversion coating for ferrous materials as well as stainless steel, and other metals. It is used to add mild corrosion resistance, for appearance and to minimise light reflection. To achieve maximum corrosion resistance the black oxide must be impregnated with oil or wax. One of its advantages over other coatings is its minimal buildup.

We used the cold method where black oxide is applied at room temperature. It is not an oxide conversion coating, but rather a deposited copper selenium compound. Cold black oxide offers higher productivity and is convenient for in-house blackening. This coating produces a similar colour to the one the oxide conversion does, but tends to rub off easily and offers less abrasion resistance. The application of oil, wax, or lacquer brings the corrosion resistance up to par with hot or mid-temperature processes. This is an excellent method for architectural finishing on steel (patina for steel) that the architect required.
There are many advantages of blackening, mainly:

• Blackening can be done in large batches
• No significant dimensional impact (the blacking process creates a layer about a micrometre thick)
• It is far cheaper than similar corrosion protection systems, such as electroplating

As this process is normally only applied to small machine parts, the challenge was to be able to use this method to treat large steel components , some over 2 metres in length.  For this prestigious but bespoke job, we created the process in house and treated the metal using custom-made tanks for dipping the material into the oxide before applying a wax to the surface to complete the job.

In addition to the blackening finish the requirement was also to make it look “aged “ by dipping the components in acid to make the surface rougher as the smoother the surface the more shine.

The Conclusion

When all the components were ready the next stage was the installation. This was done in December and early January so that the new look store within a store would be ready for opening after the end of the Winter Sales period for the new season. This included some fast turn round new components due to the nature of the handrails required by the store!
The pictures depict artist drawings from the architect of their vision for the design and close-ups of the completed blackened steel components .  All were produced and installed within the 3 week time period including the manufacture of the special tanks used in the job.

If you need specialist metal components in your commercial, retail or consumer building exercise then don’t hesitate to contact us .