What is considered the most difficult form of water to remove from lubricants?

Dissolved water is considered the most challenging form of water to remove from lubricants because it is thoroughly mixed at a molecular level with the lubricant. Unlike free water, which can separate and be drained away, or emulsified water, which can be more easily removed through specific techniques like centrifuging or using demulsifying agents, dissolved water does not present as a separate phase. Instead, it is trapped within the lubricant and can affect the lubricant's properties, such as viscosity and lubrication performance.

Dissolved water can lead to issues such as corrosion, increased wear, and a decrease in lubrication effectiveness, making it crucial for lubrication professionals to monitor and manage water content effectively. Techniques such as vacuum dehydration or the use of specific additives may be necessary to reduce dissolved water, but these processes can be more complex and time-consuming compared to addressing free or emulsified water.