technical insight
Remember: it is important to allow the material free access to the environmental oxygen to keep the passive layer intact. Special attention should be given to sheltered areas and crevices that are created by the design and installation. During routine cleaning, it is important to ensure that accumulations of contaminants are efficiently removed without damaging the material or the surface finish. This is particularly important in marine and industrial environments, where a build-up of airborne corrosive agents can result in corrosion in the form of discolouration and even pitting. On building exterior applications, stainless steel may be exposed to a wider range of potentially more aggressive environments as a result of contact with:
light discolouration. After cleaning, rinse with water and dry to avoid streaking and watermarks. Scouring powders should not be used as these products can leave scratches on stainless steel surfaces. More serious oil and grease marks can be removed with alcohol-based products or other solvents such as acetone. These non-chloride-containing products are not a corrosion hazard to stainless steel. Heavily neglected surfaces can be treated by removing most of the settled deposits with the methods mentioned earlier. The remainder can then be removed with metal polishes, such as those for cleaning chromium-plated items. Care must be taken as highly polished surfaces may become scratched with these cleaners. Cleaners for silver and brass should be avoided. How do I clean exterior surfaces? It is a good practice to clean the stainless steel at the same frequency as the building’s windows. The reasoning is simply that the same dirt build-up visible on the windows will be on all exterior surfaces, including stainless steel. A dirty window is a “clear” indication that stainless steel is also dirty. This might damage the passive layer depending on the environment. Removing the dirt will restore the passive layer in most cases. Depending on the severity of deposit build up, routine cleaning frequencies of 6-12 months for light soiling and 3-6 months for heavy soiling is advisable. How do I clean interior surfaces? The cleaning of stainless steel items for building interiors is also aimed at ensuring oxygen reaches the surface and keeping the passive layer intact. It is really no different to other materials and entails little more than routine cleaning with soap and clean water. Cleaning should be done before there is a visible build-up of soiling, so that the effort of cleaning is minimised along with the risk of discolouration. On interior applications, finger marks can be an issue. However, there is a wide range of finishes available for stainless steel, many of which are particularly suitable for use
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marine atmospheres
• environments laden with industrial pollutants • salt spray from wave action, as well as • atmospheric dirt and traffic film
A damp cloth or chamois leather, soft household soap and clean water will usually be suitable for washing and removing normal dirt. For more stubborn dirt, nylon scouring pads can be used but may scratch some polished surfaces. Metal-based scouring pads, cleaning wool, or wire brushes must not be used on stainless steel. Apart from scratching the surface, these pads can leave carbon steel deposits on the stainless surface, which can subsequently develop into rust. Non-stainless steel wire brushes must not be used. Follow the grain pattern when cleaning on “grained” directional finishes, not across it. It is advised to dry the surface to prevent watermarks, especially in hard water areas. The use of deionised (distilled) water will prevent the formation of hard water stains. For more stubborn stains, mild household cream cleansers should be effective for cleaning watermarks and
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Issue 2 – 2023
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