The SignFab Guide to Stainless Steel

This guide into Stainless Steel products has been built on the insight of Mike Smith our Operations Director. Mike is our in-house industry expert, he sits on the ISA-UK Technical Committee and the ISA-UK General Council which help steer the UK sign industry and contributes to the legal framework which governs our industry. 

Contrary to common belief, stainless steel is not just one type of material that remains “stain-less” in all circumstances. Instead, there are over 200 grades of stainless steel with different levels of corrosion resistance, although only a handful of them are commonly used in building and architecture

Polished, brushed and satin-finished surfaces are most typical of stainless steel building applications.

Regular Maintenance

To remove fingerprints and other marks
- Rinse with water to remove loose dirt.
- Wash with (preferably warm) water containing soap, detergent or 5% ammonia, using a soft, long fibre brush.
- Rinse with water.
- When cleaning brushed surface finishes, the cleaning movement should be in the same direction as the grain.

When discussing and specifying cleaning work, a distinction needs to be made between maintenance cleaning in the sense of removing dirt, graffiti etc and intact stainless steel surfaces.


Although stainless steel has a high level of intrinsic corrosion resistance, there can be isolated cases of tea staining and localized corrosion. Such damage can usually be attributed to two causes:

- Iron particles may deposit on the stainless steel surface. They may come from the cutting, welding or grinding of carbon steel in the environment or from rusty run-off water from other surfaces.

- Lack of cleaning leads to concentrations of chlorides or other aggressive substances that surpass the corrosion resistance of the stainless steel grades elected  Seaspray or chloride- laden splashes from de-icing salts are common sources of corrosive deposits. Under these deposits, tiny corrosion pits can form, which may be surrounded by a brownish halo and are commonly referred to as tea staining.

Discolouration and Incipient corrosion

Usually, discolourations are indicative of incipient corrosion. In this case, it is no longer sufficient to remove visible stains by means of cleaners

In the tiny pits, which may hardly be perceptible to the unaided eye, corrosive media or corrosion products may be trapped, which will cause new stains to form.
It has to be borne in mind that acid-containing specialist stainless steel cleansers may damage other metallic materials like aluminium or galvanized carbon steel. When applying them, care has to be taken to protect components such as aluminium window frames or galvanized support structures. Also decorative stone is susceptible to damage by acidic cleaning products. For this reason, remedial cleaning should only be performed by experienced specialist companies, taking all reasonable health, safety and environment precautions.