Deterioration

Deterioration is the gradual loss of the health (hit points) of certain objects. Affected objects include clothing, armor, weapons, and most resources. Deterioration is applied to an object that is not under a roof. Whether the object is indoors or outdoors does not matter, therefore a roofed room without a door still provides protection. Mountains have an indestructible roof making them well-suited to protect perishable items. When an item's health reaches 0 it is destroyed.

Deterioration is applied to apparel (armor and clothing) when worn. A colonist wearing any apparel with health 20% or below will get the 'Wearing tattered apparel' thought. A colonist wearing any apparel with health between 21% and 50% will get the thought 'Wearing frayed apparel' thought.

Artillery shells that deteriorate to 0 health will explode.

Packaged survival meals which needed no special care before deterioration was introduced, now will decay quickly without protection.

Deterioration Rate

An object's deterioration rate specifies how much health is lost per day. Rain greatly multiplies deterioration rate. As an object loses health it also loses it's market value very quickly. Objects lose other stats as well:

Gear suffers lowered armor protection and insulation.

Ranged weapons suffer lowered accuracy.

Melee weapons suffer lowered melee damage.

Immunity

Resources that are immune to deterioration are metal, stone, leather, and hyperweave cloth. However, objects crafted from these materials lose that immunity.

Glitterworld medicine is also immune.