If ash is not cleaned from insulators immediately following fallout then, with subsequent adsorption of moisture (e.g. mist, fog, light rain, etc.), ash will adhere strongly (i.e. cement) to all surfaces (making cleaning difficult) and cause latent effects such as flashover, corrosion and tracking. Burning and etching caused by tracking and leakage current (initiated by conductive deposits of ash) can deteriorate apparatus, degrade insulator surfaces and thereby compromise operating performance. Insulator orientation and moisture are the key factors determining the severity of ash adherence.