Another factor that affects the physical properties of nylon and plastics in general, is the chemical nature of the application environment. During normal use, nylon features excellent resistance to chemical attack and is particularly impervious to hydrocarbon esters, ketones and ethers; despite these characteristics, nylon can absorb a certain quantity of hydrocarbons and small percentages of water that can lead to dimensional alterations. Other solvents, such as strong mineral acids, metal salts and formic acid attack nylon severely, even at ambient temperature. When choosing nylon for applications, it is therefore important to consider the nature of solvents, temperature, and stress in order to predict the relative effects.