Some reasons why stainless steel surfaces may require cleaning.
A stainless steel may be discoloured during use
- if it has a rough surface finish that provides a foothold for corrosive substances and corrosion products from the surroundings.
- if fasteners from ordinary steel are used for securing the material, or if the material comes in direct contact with adjacent components made of plain carbon steel in wet or humid conditions.
- if the design of the structure is inappropriate, with pockets and narrow gaps
- if the surface is contaminated by iron particles, for example swarf etc. from tools used in the installation works.
- if it is exposed to a more aggressive environment than that for which that particular grade of steel is intended, e.g. highly polluted air, salt solutions or residuals of cleaning agents.
The risk of corrosion is grater for the lower-alloy stainless steel grades and can be reduced substantially right from the start by specifying more highly alloyed grades. In the case of surface contamination from carbon steel, it is the rust from the carbon steel that causes discolouration.
Removal of Stains
| Stain Type |
Cleaning agent and method |
| Fingerprints |
Wash with soap, alcohol, thinner, thrichlorethylene or acetone, rinse with clean cold water, and wipe dry. |
| Oil and grease |
Wash with organic solvents, such as those mentioned above, then wash with soap or mild detergent and water, rinse with clean cold water, and wipe dry. |
| Tea and coffee stains |
Soak for 15 minutes in a hot solution of washing soda (sodium carbonate) or baking soda (sodium bicarbonate). Rinse with cream cleanser e.g. CIF®, clean water and wipe dry. |
| Burnt on food or carbon deposits |
Pre-soak in hot water with detergent or ammonia solution. Remove deposits with nylon brush and fine scoring powder if necessary (can leave scratch marks). Repeat if necessary and finish with "routine cleaning". |
| More stubborn stains and discolourations |
Wash with a mild cream cleanser e.g. CIF®, apply with soft cloth or soft sponge and rub in the direction of the visible surface structure, rinse with clean cold water, and wipe dry. Or: Wash with a 10% phosphoric acid solution, rinse with ammonia solution, then with clean cold water, and wipe dry. AvestaPolarit cleaning agent 401 can be used for more stubborn stains and discolouration. It must be rinsed thoroughly with clean water and wiped dry. However, due to the chemical composition of such cleaners, it is essential that the manufacturer's instructions are strictly followed. |
| Temper colour and more serious stains |
Wash with an abrasive detergent as described above. Or: Rub with Scotch Brite sponge in the direction of the visible structure, rinse with clean cold water, and wipe dry. |
| Adherent hard water scales |
Soak in 25% acetic acid or citric acid solution, use a nylon brush to remove deposits, rinse with clean water and wipe dry. |
| Rust stains |
Wet the surface with oxalic acid solution, leave it for 15-20 minutes, rinse with clean cold water, and wipe dry. If necessary, repeat the washing procedure with a cream cleanser as described above. |
| Paint, graffiti |
Wash with paint solvent (use a soft nylon brush), and rinse with clean cold water, and wipe dry. |
Protective measures
Use acids (acetic acid, citric acid, oxalic acid, phosphoric acid) only if other methods have proved inadequate. Wear rubber gloves and protective goggles, and follow your local safety regulations for such work. Ensure good ventilation when using solvents and note the risk of fire.