It’s ‘Stainless’ not ‘Non-Stain’


As Grahame Ansley, one of Anzor’s directors likes to say, stainless steel is ‘stainless’ not ‘non-stain’.Yes stainless steel is corrosion resistant, but depending on a range of factors – the grade, the environment, exposure to rainwater, the surface finish, etc; stainless steel products may be subject to ‘tea staining’ (surface rust) or rusting. Therefore they may require regular cleaning to reduce the risk of this happening.

Have a look at the photo below. It shows a stainless steel tube structure supporting a canopy. It is 3km from the coast, so not particularly close to the sea. You will see that the stainless tube directly below the canopy is obviously tea staining (see B) but the legs are not. Why? Because the canopy is sheltering the tube from rainwater, not allowing it to be washed. This means salt and pollutants build up, eventually damaging the chromium oxide layer that protects the stainless steel, and causing tea staining.

That’s the first issue. The other is the surface finish of the stainless steel. Up close (see A) it looks to be a brush finish that has fine grains running through it. Again this causes issues as these grains trap salt, etc. This builds up and damages the chromium oxide layer, causing tea staining, albeit to a lesser extent on the legs because they are washed by rainwater.

Ideally, this tube should have been specified with a smoother finish which is then electro-polished for enhanced protection. As it has not, the building owner should instigate a cleaning program. We would suggest chemically cleaning the tube to remove the tea staining, and then start a cleaning program whereby it is washed with soapy water every 3-6 months (depending on how soon the tea staining show signs of coming back). An application of Prolan after the chemical cleaning would protect the stainless steel from salt, and reduce the frequency of required cleaning.

In summary, stainless steel may require regular cleaning to maintain its corrosion resistant properties. In our experience, often the people enjoying the stainless products on their building, or boat, or balustrade, don’t realise this – they think stainless is ‘non-stain’!