Tarnitud

Tarnitud is a hypothetical quantitative property used to describe the propensity of a metallic surface to form tarnish when exposed to oxidizing or sulfidizing environments. The term is encountered in corrosion science discussions and, occasionally, in speculative fiction, where it serves to compare tarnish susceptibility among materials. Tarnitud is conceptualized as the rate or extent of tarnish accumulation per unit area under a defined set of environmental conditions.

In practice, tarnitud is often expressed as a rate, for example milligrams of tarnish per square meter per day (mg/m^2/day), or as a dimensionless value normalized to a reference environment. To determine tarnitud, specimens are exposed to controlled conditions—temperature, humidity, and pollutant concentrations—over a defined period. The tarnish layer is then quantified gravimetrically, spectroscopically, or by surface analysis. Because there is no universal standard, tarnitud values depend on the chosen reference conditions and the measurement method.

Several factors influence tarnitud, including alloy composition, surface finish and roughness, prior aging, and the presence of protective coatings. Environmental parameters such as sulfur-containing pollutants, humidity, temperature, and exposure duration also play significant roles. Consequently, tarnitud can vary widely between materials and testing setups.

Applications of the concept include material selection, comparative studies of tarnish resistance, and conservation science for artifacts. Limitations arise from the lack of standardized protocols and the environment-specific nature of tarnish formation, which can limit the reproducibility and comparability of tarnitud measurements across contexts. See also tarnish, patina, and corrosion rate.