Systems and methods for forming protective coatings

A method for forming a protective coating on a substrate, the method comprising:

• providing a substrate;
• forming a first polyurethane coating layer on the substrate, the first polyurethane coating layer formed on the substrate in such a way that the first polyurethane coating layer reaches a touch dry state within a first time period (T1) after the first polyurethane coating layer is provided on the substrate;
• applying a treatment consisting of a first evaporable solvent on the first polyurethane coating layer, wherein the
• first evaporable solvent is applied on the first polyurethane coating layer within a second time period (T2) after the first polyurethane coating layer reaches the touch dry state that a top sub-layer of the first polyurethane coating layer has undergone substantially complete cross-linking while sub-layers beneath the top sub-layer have undergone only partial cross-linking;
• and
• forming a second polyurethane coating layer on the first polyurethane coating layer, wherein:
• the second polyurethane coating layer is formed on the first polyurethane coating layer within a third time period (T3) after applying the first evaporable solvent;
• the first evaporable solvent applied on the first polyurethane coating layer is partially evaporated before the second polyurethane coating layer is provided on the first polyurethane coating layer;
• partial cross-linking reaction occurs in the sub-layers beneath the top sub-layer of the first polyurethane coating layer when the second polyurethane coating layer is provided on the first polyurethane coating layer;
• and
• the second polyurethane coating layer reaches the touch dry state within a fourth time period (T4) after the second polyurethane coating layer is provided on the first polyurethane coating layer.