Combating oil Varnish with standard testing at Hastings Deering.

Following 6 months of strict testing, the Hastings Deering Laboratory is now able to offer Varnish potential tests as part of its standard Scheduled Oil Sampling (S.O.S) analysis procedures in the SOS13 kit.

Based on the Fluitec World Standard testing for Varnish Deposits, this test previously required up to 200ml of oil for a single test, making it impracticable in the current laboratory processes.

Cameron Hoswell, Product Support Representative Laboratory Services at Hastings Deering said that the team worked on new processes to ensure that they could reproduce this testing in a way that was suitable for customers within the current sample collection processes.

“Essentially, we were looking to develop a means to test for varnish with the normal sample bottles used in our labs, making it easier for our customers to start picking up varnish in oils,” he states. “Its about making this test more accessible.”

“We needed to condense the product down so that we were using less fluid,” he states. “There are too many machines with high varnish levels and issues, so we worked through a lot of tests over 6 months to get this over the line working with representative volumes.”

Working with Karen Brady and Steven Tomovich from the Hastings Deering Lab, Mr. Hoswell said they were able to successfully replicate testing with smaller volumes of fluid.


“The key was to make sure we were able to scale it down, so that we could replicate the test to the same levels as the World Standard.”

“We’ve seen oil samples in good condition, where the total acid number is normal, the viscosity is normal, where oxidation is normal, but the oils are rejected due to the high varnish levels.”

The leading reason why hydraulic oil users are unable to detect varnish problems with their fluid, is due to inadequate oil analysis testing.

“Oil degradation and deposit formation are not being measured in most condition monitoring programs,” said Mr. Hoswell.

Hydraulic oils are subject to increased thermal and mechanical stresses in modern hydraulic systems causing varnish deposits. With varnishing, some brands and machines will develop more varnish than others, due to the machine construction, and restricted flows and inadequate cooling system capacity leading to component heating. 

Varnish plates itself on pumps, bearings, cylinders, and sleeves in hydraulic units and causes heating of components which leads to damage and failure.

Hydraulic oil formulations are constantly being updated to accommodate these more stressful environments; however, varnish problems persist. 

“The more varnish that is produced within the machine, the worse it gets and more difficult it becomes to act upon. Critical pieces of machinery can be impacted.”


“This test can be run in 4 days as part of our SOS13 hydraulic testing. It allows us to keep an eye on our machines and our customers fleets.”

“It’s a really unique offer, and we’re now able to provide this full test suite for Hydraulic machinery. The more tests we run, the more we’re able to pick up unrelated issues that can help save our customers money and productivity.”

Understanding the impact of varnish within active machinery, enables the laboratory team to provide recommendations on oil management and required oil changeouts, helping to reliably maximise the service life of the oil.

There are multiple technologies suitable for mitigating hydraulic oil varnish once the problem has been identified including, filtration technologies like electrostatic oil cleaning and depth media filters or adding solubility enhancing agents to the in-service oil.

“This test now enables us to help identify and solve issues for our customers across a range of industries.”

“At the end, customers benefit, machines last longer and we’re able to control varnish until it needs to be changed.”

Download the white paper for more information: Developments in Measuring and Managing Hydraulic Oil Degradation

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