Cleaning stainless steel

Stainless Steels are inherently corrosion resistant materials that do not need additional surface protection to enhance their appearance and durability. Some routine maintenance and cleaning is needed to keep stainless steel surfaces in good condition, so that the aesthetic appearance and corrosion resistance are not compromised.
The following guidelines give advice on how to efficiently and cost-effectively clean stainless steel surfaces, profiting from corrosion-resistance properties.
When applied outdoor, stainless steel may be exposed to a wide range of potentially aggressive environments, as a consequence of the contact with:
- marine atmospheres;
- Industrial environment laden with polluting agents;
- Road deicing salt splashes,
- Athmospheric and traffic pollution.

All of them cause dark staining. It is therefore important to clean stainless steel façade elements as often as windows and glass walls. According to the amount of dirt deposits, the recommended routine cleaning frequencies are of 6-12 months for mild dirt and of 3-6 months for stubborn dirt deriving from the abovementioned environments. This form of contamination can be removed by means of stainless steel cleaners containing phosphoric acid.
It may occur tiny particle deposits. At an early stage, light deposits can be removed using nylon pads, such as the “Scotch-Brite” type used in kitchen work. Alternatively, the contamination can be removed with a specific phosphoric-acid-based stainless steel cleaner.

Should pitting occur, depending on its severity, acid pickling treatments will be needed to restore the damaged surface. In this case, pickling agents in paste form are available for localized, on-site application. They should be used in accordance with the manufacturer’s directions, so that they are managed and applied safely and in compliance with the relevant legislation on environmental protection.
For outdoor applications, i.e. façades, rainfall is usually sufficient to wash off accumulations of dirt and other deposits efficiently, depending on the amount of exposure of the architectural element. During routine cleaning, special attention should be paid to sheltered areas in order to ensure that accumulations of airborne contaminants are removed. This is particularly important in marine and industrial environments, where airborne chlorides or sulphuric build-ups can result in localized corrosion, if not effectively removed.
The safest and most effective products to remove fingerprints or other marks from architectural finishes are soapy water or a mild detergent.
Proprietary spray products are available, combining ease of cleaning with a light film which results in a uniform gloss.
Address the nearest national stainless steel development association to obtain further advice on locally available products.
Abrasive products are advised against, as they can leave scratches on stainless steel surfaces.

Heavy damaged surfaces can be treated with metal polishes, such as those used to clean chromium-plated items (e.g. car finishes). Attention must be paid, however, when using these products on very glossy surfaces, as they can be scratched.
As an alternative, to remove contamination, it can also be used a specific stainless steel cleaner containing phosphoric acid.
Before starting any treatment, be sure to have received all safety guidelines from supplier clearly. If in doubt, please contact suppliers again to seek specific clarification and advise.

Cleaners which should NOT be used on stainless steel include:
- cleaners containing chlorides, especially those containing hydrochloric acid,
- hypochlorite bleaches. If accidentally spilled on any stainless steel surface, they must be thoroughly rinsed off with plenty of clean water,
- Silver cleaners.

Indeed, non-stainless steel abrasive or wire wools must not be used, as they not only scratch the surface, but may also leave carbon steel deposits which can subsequently develop into rust stains, if the surface becomes damp.
In order to avoid cross-contamination caused by iron particles, make sure that the cleaning tools chosen have not been used for cleaning carbon steel before. Cleaning materials to be used on stainless steel, in fact, should be exclusively used for that purpose.