On metal, patina is a coating of various chemical compounds such as oxides, carbonates, sulfides, or sulfates formed on the surface during exposure to atmospheric elements. They may also be aesthetically appealing.

Patinas can provide a protective layer to materials that would otherwise be damaged by corrosion or weathering. Patina is a tarnish that forms on the surface of copper, bronze and similar metals stone a sheen on wooden furniture produced by age, wear, and polishing or any such acquired change of a surface through age and exposure. It also refers to development as the result of weathering of a case-hardened layer, called 'cortex' by geologists, within the surface of either a flint or chert nodule.Freebase (5.00 / 1 vote) Rate this definition: In geology and geomorphology, the term 'patina' is used to refer to discolored film or thin outer layer produced either on or within the surface of a rock or other material by either the development of a weathering rind within the surface of a rock, the formation of desert varnish on the surface of a rock, or combination of both. This has led stone tool analysts in recent times to generally prefer the term 'cortification' as a better term to describe the process than 'patination'. Patina also refers to accumulated changes in surface texture and colour that result from normal use of an object such as a coin or a piece of furniture over time.ДЄrchaeologists also use the term 'patina' to refer to a corticated layer that develops over time that is due to a range of complex factors on flint tools and ancient stone monuments. On metal, patina is a coating of various chemical compounds such as oxides, carbonates, sulfides, or sulfates formed on the surface during exposure to atmospheric elements (oxygen, rain, acid rain, carbon dioxide, sulfur-bearing compounds), a common example of which is rust which forms on iron or steel when exposed to oxygen. Patinas can provide a protective covering to materials that would otherwise be damaged by corrosion or weathering. Patina (/Л€pГ¦tЙЁnЙ™/ or /pЙ™Л€tiЛђnЙ™/) is a thin layer that variously forms on the surface of stone on copper, bronze and similar metals (tarnish produced by oxidation or other chemical processes) on wooden furniture (sheen produced by age, wear, and polishing) or any such acquired change of a surface through age and exposure.

The final-two fotos are shown ''after'' burnishing and sealing. The first-two fotos show surfaces ''as acquired''. The surface is ''shiny'' and highly reflective.ДЄnd what remains are beautiful hints of blue, deep-gray, plum-brown,ДЄnd maybe just a hint of golden, yellow-orange.Д«elow are some fotos of Dave Stromberger's 1919 Flying Merkel bicycle. Hopefully the surface has not been polished to the point where Some consider it a wise move to seal the surfaces after burnishingДЄnd wipe-down. the now-smoothДЄnd ''dustless'' metallic-surface is thought to be ''in patina''. say with 0000-steel wool plusДЄ neutral, non-oily fluid. However, if a person were to lightly burnish (gently clean) the areasДЄvailable to the hand / rag. More than a few of us refer to this as ''rust''. Some of the iron oxide may transfer to the hand / rag. If a person can run a hand or rag over this surface, When the rust is left to continue to oxidize. Into contact with ferrous-metals is a good recipe for rust. Oxygen in the presence of atmospheric-moisture coming Aging is the oxidation of most-everything else -Д¬ould be there are many things that do not show that they are

Rust and patina crossword