PATINA (/) As a word we use in steel finishing, is basically “Controlled Corrosion”. We control the colors by mild chemical reaction with the iron content in the steel. It is fast, safe & easy to master. It also adds a significant amount of value to your work.
It is commonly used in reference to a tarnish of various colors, that forms on the surface of copper, bronze and similar metals (produced by oxidation or other chemical processes); stone; a sheen on wooden furniture produced by age, wear, and polishing; or any such acquired change of a surface through age and exposure.
Patinas can provide a protective layer to materials that would otherwise be damaged by corrosion or weathering. They are very aesthetically appealing in most cases. Even rusty steel has a patina & character that is highly sought after in architecture, art & crafts, as opposed to painted steel.
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, oxides), a.k.a. “rust”. Rust’s technical name is iron oxide.
Patina also refers to accumulated changes in surface texture and color that result from normal use of an object such as in an old knife, tool or even metal furniture, over time.
Artists and metalworkers often deliberately add patinas and dyes as a part of their design and decoration of art and furniture, or to simulate antiquity in newly-made objects. The process is often called distressing or antiquing. It greatly adds to the marketability & “wow factor” of metal art, especially plasma-cut art.
A wide range of chemicals, in proper proportion & combination, can give a variety of patinas and color changes to steel.
They are often used by metal crafters, plasma-cutters & artists as surface embellishments either for color, texture, or both. Some patinas for steel contain very small amounts of acid, hence the name “Acid-Wash Patinas”, but the ratio of chemicals to water is so low that they are very safe when used as directed.
Patination composition varies with the reacted elements and these will determine the color of the patina.