Chlorine Gas

Chlorine Gas is a gaseous element that appears naturally in the world and can also be produced by the Chlorine Gas Vent and the Rust Deoxidizer. It can be found in Chlorine Clouds on space missions, and small amounts of liquid Chlorine may occur naturally in the Frozen Biome because of its relatively high condensation point. In its liquid form, it has very low thermal capacity and conductivity, which makes it useful in a few niche cooling or storage setups.

A Chlorine-filled room is especially valuable for disinfection and temperature control. Contact with Chlorine Gas quickly kills germs on the contents of machines and storage buildings, making it a strong choice for treating contaminated materials such as slime and other germy supplies. It does not disinfect germs inside pipes, so any liquid or gas moving through piping will remain contaminated until it is exposed outside the pipes. Germ removal also takes a full cycle, so Chlorine rooms are better suited to storage, processing, and slow sanitization than to instant treatment.

Chlorine can also serve as an early, more durable substitute for a vacuum chamber. It is not as effective as abyssalite-based insulation, but its low density makes it a poor heat buffer even when pressurized, which is still useful when building isolated environments. Since Chlorine does not directly harm duplicants beyond the normal effects of breathing a non-breathable gas, it can be handled safely as long as the colony accounts for oxygen access and movement.

Several buildings and critters interact with Chlorine in useful ways:

• The Ore Scrubber removes germs from items and consumes Chlorine in the process, but it requires duplicant labor and item handling.
• Balm Lily must be surrounded by Chlorine and needs no tending, making it ideal for low-maintenance medical supply chains.
• Dasha Saltvine requires a Chlorine atmosphere and consumes only small amounts over time.
• Gas Grass uses liquid Chlorine as irrigation.
• Puft Princes and Squeaky Pufts can breathe Chlorine and produce Bleach Stone, which is then used by Hand Sanitizers, Hot Tubs, Waterweed, and Geotuners.

Because Chlorine is renewable, excess gas can be vented or stored if a colony has more than it needs. It is also possible to harvest it from space missions in Chlorine Clouds and Radioactive Gas Clouds, giving late-game colonies another source. For colonies that need germ control, sterile storage, or Chlorine-dependent crops and critters, it is one of the most useful specialty gases in the game.