Anti-rust paper, also known as vapor phase inhibitor (VPI) paper, is a type of packaging material designed to protect metal objects from rust and corrosion. It contains chemicals that release vapors that form a protective layer on the surface of metals, inhibiting the oxidation process. It is commonly used in manufacturing, storage, and transportation of metal parts, tools, and machinery to prevent rust formation during shipping and storage.
The development of anti-rust paper came about as a response to the need to protect metal products from rust during storage and transportation. With the growth of industrial manufacturing and international trade, protecting metal items from environmental factors that cause corrosion became crucial. Anti-rust paper has evolved with advancements in corrosion-inhibiting chemicals and packaging technology, becoming more effective and versatile over time.
The main purpose of anti-rust paper is to protect metal surfaces from rust. It is used to wrap metal parts, components, and tools, creating a microenvironment around the metal that prevents moisture and oxygen from reaching the surface, which are the primary causes of rust. It is especially useful for protecting ferrous metals like steel and iron, but can also be effective on other metals depending on the type of inhibitor used.
Anti-rust paper operates based on the principle of vapor phase inhibition. The paper is impregnated with volatile corrosion inhibitors (VCIs). These chemicals vaporize at room temperature and adsorb onto the metal surface, forming a thin, invisible layer that acts as a barrier against moisture and oxygen. This layer prevents the electrochemical reactions that lead to rust formation, protecting the metal even in humid or corrosive environments.