ISO 12944-6:2018 specifies laboratory test methods and test conditions for the assessment of paint systems for the corrosion protection of carbon steel structures. The test results are intended to be considered as an aid in the selection of suitable paint systems and not as exact information for determining durability. ISO 12944-6:2018 covers protective paint systems designed for application to uncoated steel, hot dip galvanized steel according to ISO 1461 and steel surfaces with thermal-sprayed metallic coating according to ISO 2063‑1 and ISO 2063‑2. ISO 12944-6:2018 does not apply to protective paint systems for electroplated or painted steel. The environments for corrosivity categories C2 to C5 and Im1 to Im3 defined in ISO 12944‑2 are considered.