A sealer developed by researchers at Yonsei University in Korea incorporates microcapsules of a urea-formaldehyde polymer. The microcapsules provide the sealer with a self-healing property. This can then be sprayed onto the surface of concrete or mortar. When the self-healing coating is damaged, the healing agent is released from ruptured microcapsules and fills the damaged region. The coating was evaluated as protective coating for mortar; using water permeability and chloride ion penetration tests the inventors demonstrated that the sealer has sunlight-induced self-healing capability. The research was published in the ACS Journal, Applied Materials & Interfaces.