[0059] In some embodiments, the polymeric particles can comprise foamed polymers. 

[0060] In some embodiments, the polymeric particles can comprise unfoamed polymers. 

[0061] In some embodiments, the solid particles can be of hollow and/or porous construction. 

[0062] In some embodiments, the polymeric particles can have an average density of from about 0.5 to about 3.5 g/cm 3 • 

[0063] In some embodiments, the non-polymeric particles can have an average density of from about 3.5 to about 12.0 g/cm 3 • 

[0064] In some embodiments, the polymeric or non-poly› meric particles can have an average volume in the range of about 5 to about 275 mm 3 • 

[0065] In some embodiments, the solid particles can be reused one or more times for cleaning of metal substrates according to methods of embodiments of the invention. 

[0066] In some embodiments the method can further com› prise a step of recovering the multiplicity of solid particles after cleaning of the metal substrate. In further embodiments, the method can comprise separating the multiplicity of solid particles from the cleaning formulation. 

[0067] In some embodiments, the cleaning formulation can comprise one or more components selected from the group consisting of: solvents, polymers, corrosion inhibitors, build› ers, metal chelating agents, surfactants, dispersants, acids, bases, anti-oxidants, reducing agents, oxidising agents and bleaches. 

[0068] In some embodiments, the method can further com› prise coating the metal substrate after cleaning the metal substrate. The coating can be a protective coating or lacquer. 

[0069] In some embodiments, the metal substrate can com› prise a transition metal. 

[0070] In some embodiments, the metal substrate can com› prise aluminum. 

[0071] In some embodiments, the metal substrate can be a metal alloy. 

[0072] In some embodiments, the metal substrate can com› prise a metal sheet. 

[0073] In some embodiments, the metal substrate can be a metal can such as an aluminum can. 

[0074] In some embodiments the method can further com› prise shaping or forming the metal substrate. Said shaping or forming can be prior to, or subsequent to, the cleaning steps of the method of the invention. The shaping or forming of the substrate can be to create a final desired form of an article, such as a can, orto form a precursor to said final desired form. 

[0075] Further embodiments of the present invention can provide a method of treating a metal substrate. The method of treating can comprise: 

a) cleaning the metal substrate in accordance with an embodi› ment of the invention hereinabove disclosed, and 

b) removing at least a portion of an oxide layer from the surface of the cleaned substrate. 

[0076] In some embodiments, step b) can comprise expos› ing the metal substrate to a treatment liquor comprising a treatment formulation and a multiplicity of solid particles. 

[0077] In some embodiments, step b) can further comprise causing the solid particles and the metal substrate to enter into contacting relative movement. 

[0078] In some embodiments, the treatment formulation can comprise one or more promoters selected from the group consisting of acids, bases and surfactants. 

[0079] In some embodiments, the one or more promoters can comprise at least one metal chelating agent. 

[0080] In some embodiments, the one or more promoters can comprise at least one carboxylic acid moiety. 

[0081] In some embodiments, the one or more promoters can comprise two or more carboxylic acid moieties. 

[0082] In some embodiments, the one or more promoters can comprise at least one citrate moiety. 

[0083] In some embodiments, the one or more promoters can comprise at least one surfactant. 

[0084] In some embodiments, the at least one surfactant can be a non-ionic surfactant. 

[0085] In some embodiments, the solid particles can be in accordance with one or more of the embodiments herein› above disclosed. 

[0086] In some embodiments, the method of the treating the metal substrate can comprise passivating the metal substrate. 

[0087] In some embodiments, the method of the treating the metal substrate can comprise inhibiting the re-growth of an oxide layer on the surface of the metal substrate. 

[0088] Further embodiments of the invention disclose a metal substrate obtainable or obtained by the method of one or more embodiments of the invention hereinabove disclosed. 

[0089] In some embodiments, the metal substrate can com› prise an oxide layer with a thickness of less than 15 nm as measured by X-ray photoelectron spectroscopy. 

[0090] In some embodiments, the metal substrate can com› prise an oxide layer with a thickness of less than 10 nm as measured by X-ray photoelectron spectroscopy. 

[0091] In some embodiments, the metal substrate can com› prise an oxide layer with a thickness of less than 6 nm as measured by X-ray photoelectron spectroscopy. 

[0092] In some embodiments, the metal substrate can com› prise an oxide layer with a thickness of less than 5.4 nm as measured by X-ray photoelectron spectroscopy. 

[0093] In some embodiments, the metal substrate can com› prise an oxide layer with a thickness of less than 3.8 nm as measured by X-ray photoelectron spectroscopy. 

## BRIEF DESCRIPTION OF THE DRAWING 

[0094] FIG. 1 shows images of a pre-corroded mild steel substrate, a pre-corroded mild steel substrate treated in accor› dance with the invention and an un-corroded mild steel sub› strate. 

[0095] In certain embodiments, the method of the present invention involves cleaning a metal substrate by contacting the substrate with a cleaning formulation and a multiplicity of solid particles ( also referred to herein as "a solid particulate material"). The metal substrate is contacted with the solid particulate material such that unwanted materials and con› taminants including, but not limited to, fines (small particles of the metal) and smut, lubricants such as oils, lubricant residues, coolant residues, inorganic or organic salts, surfac› tants, biocides, emulsifiers and fungicides, are removed sub› stantially or completely from the surface of the substrate. 

[0096] The contact between the metal substrate and the solid particulate material surface can comprise a mechanical interaction and, in order to achieve this effect, contacting relative motion can be imparted between the metal substrate and the solid particulate material. 

## DETAILED DESCRIPTION 

