Deterioration is the gradual loss of the hit points of certain items. An item is anything that can be hauled by a colonist. Deterioration is akin to an item taking damage from projectiles, explosions, or fire since they all affect the same hit points stat. Affected items include clothing, armor, weapons, and most resources. Deterioration is applied to an item that is not placed in a safe place. An item being in an outdoor area, water, sea, or swamp will trigger the deterioration.
A shelf protects any item. Mountains have an indestructible roof making them well-suited to protect perishable items. But be careful when re-constructing the walls; if the roof collapses, everything underneath will be buried.
When an item's hit points reach 0, it is destroyed.
- Deterioration is also applied to apparel (armor and clothing) when worn. A colonist wearing any apparel with hit points 50% or below will get the -3 thought "Ratty Apparel." If any items fall below 25%, the thought will worsen to a -5 "Tattered Apparel."
- A colonist does not, however, receive negative thoughts for using deteriorated weapons.
- Artillery shells that deteriorate to 0 hit points will explode.
- Raw food deteriorates in addition to still being prone to spoilage.
- Equipped weapons do not deteriorate.
- As an item loses hit points, it also loses its market value very quickly. This only seems to apply to certain items - weapons, apparel and artificial body parts decrease in value, while materials, medicine and drugs do not. The exact determining factor of whether an item will drop in value as it deteriorates is currently unknown.
- A finished product is not influenced in any way by the deterioration of its ingredients.
- In the past, deterioration lowered the effectiveness of weapons and armors, but that is no longer the case.
An item's deterioration rate specifies how many hit points are lost per day. Depending on the type of item, it ranges from 0.25/d to 10.0/d. This stat is listed in an item's information tab. If this stat is not listed or listed as '0.00/d', then the item will not deteriorate. Rain greatly affects the deterioration rate. For items with the quality stat, a high-quality item will have a lower deterioration rate than a poor quality item.