One of the major problems with turbine lubricants is it formation of varnish. Varnish is formed from many fluid issues. In the broadest term, varnish can be considered as deposits from the lubricant - since all yield similar issues. In reality, deposits have a wide range of different chemistries depending upon the formulation of the lubricant, the application, the mode of degradation and interaction with contaminants. Understanding the chemistry of the deposits is important for two reasons. First, the chemical make-up of the deposit provides key insights into the root cause of the deposit. Determining the cause of the deposit allows plant operators in many cases to address the root cause of the problem and prevent similar deposits from impacting their operations in the future. Second, understanding the chemistry of the deposit becomes important if one is installing a contamination control technology designed to remove the contaminant and prevent deposit formation issues. Each type of deposit may require a different treatment technology.