Definition - What does Exudation mean?
Exudation is a process that occurs when matter that is a part of the composition of another material begins to rise or penetrate outward towards the surface of the material it is part of or contained by. Problems can occur in regards to corrosion if coatings are subject to exudation.
Corrosionpedia explains Exudation
Exudation can be used to define a wide variety of instances of outward surface penetration. For instance, a cut on someone's hand can cause blood to exude from the skin. Some trees exude sap when the conditions are right. Magma can exude from the core of the earth. Exudation can cause plasticizer additives to rise to the surface of a polymer.
Exudation occurs in certain types of paints. If the water-soluble components of paint are subjected to high moisture and humidity then exudation can occur. This could ultimately result in a coating failure and corrosion. Coatings should be carefully selected to avoid exudation in humid environmental conditions.