Got varnish? We have answers


If you find a little varnish in a hydraulic reservoir, there's probably a lot more distributed throughout the hydraulic system.

Varnish in hydraulic systems starts off as soft, insoluble contaminants that are so small  they pass right through filters and go undetected by particle counters. They collect throughout a hydraulic system and can eventually become varnish that causes valve sticking and other system malfunctions.

These insoluble soft contaminants caused by a combination of water, heat, and oxygen. The heat is caused by static discharge, a process discovered several years ago that damages a filter's center core. Now, with additional study, there is solid visual proof that static discharge occurs throughout the entire hydraulic system, causing the formation of tar and varnish and reduced system performance.

Read the whole story by clicking here.

Please or Register to post comments.

What's The Hitch Post?

Observations about fluid power and other technologies, technical writing, and unrelated topics


Alan Hitchcox

Alan joined Hydraulics & Pneumatics in 1987 with experience as a technical magazine editor and in industrial sales. He graduated with a BS in engineering technology from Franklin University and...
Blog Archive

Sponsored Introduction Continue on to (or wait seconds) ×