Drying Agents are any substance that serves to remove the moisture or liquidity from a substance. They fall into two categories: Desiccants for removing water from a substance or atmosphere, and Oil Drying Agents for hardening oil substances.
Desiccants are most often seen in packaging to keep the contents of a package or crate dry during storage and shipping. They remove moisture from the air and their immediate surroundings, and are often found as paper packets in pill bottles, shoes, and computer equipment. Two of the most common desiccants are Silica Gel and Calcium. While many desiccants are natural elements or compounds, some must be formed from raw ingredients. Many of them are also toxic to organic life in large quantities; Salt is harmful to bacteria, but not to larger animals. The Silica Gel Agents, which form the bulk of consumer drying agents, are considered dangerous if ingested but otherwise harmless, and they do not harm the environment when discarded.
Oil Drying Agents do not remove moisture, as Oils generally do not have any moisture in their structure, but instead serve to harden the liquid oils by Chemical Cross-Linking; the large polymer molecules of the oils are linked together to form a stable network. They are mostly composed of metallic elements including lead, cobalt, iron, and zinc; these can be dangerous to water tables and wildlife if discarded in great quantities.