Stainless Steel requires regular cleaning and maintenance. Poorly specified, designed, manufactured or maintained Stainless can suffer rust discolouration often known as Tea-staining.

If tea-staining does occur, the Nickel Institute recommends application of a phosphoric acid gel to remove the staining and restore the surface of the stainless steel.

Grunt Emergel is recommended for the use of removing:
- Rust stains and Tea-staining on Stainless Steel, such as on stainless wire rope - see Stainless Steel Tea-staining.
- Heavy weathering oxidation and other stains from gel-coat, enamel and lacquer surfaces, ideal for the underside of gel-coat boats.