This guide will provide definitions for 5 key criteria for environmentally friendly rail curve greases, and an understanding of how each is measured.

Key Criteria

Large volumes of rail curve lubricants are used in rail networks globally to help extend the life of the rail track and train wheels by minimising friction and wear at the wheel/rail interface. The lubricants used are part of what’s known as a ‘total loss’ system, in that once the grease has done its job at the gauge face of the rail, it is deposited onto the track bed and into the environment. That is why when selecting a gauge face grease for your network, it is imperative that you consider the environmental properties of a grease so that your impact on the environment and sensitive ecosystems is minimised. 

There are a lot of environmental terms and claims used in the lubricants industry, this guide attempts to take a closer look at the common environmental terms and phrases, explain what they mean and how they are measured, and most importantly what that means for the end user and the sensitive ecosystems that your rail network passes through.


What does Biodegradable mean?

The biodegradability of a product is measured by the length of time its materials take to break down into natural elements after use. The quicker the substances within a rail lubricant decompose, the higher the rate of biodegradability and the less impact it will have on the environment.

How is it Tested?

The biodegradability of a product is measured through the internationally accepted OECD 301B testing standard. This method uses respirometry to determine the biodegradability of a material by evaluating how much CO2 a microorganism can produce over a minimum of 28 days in a liquid environment.

Testing materials using OECD 301B leads to different biodegradability grades:

Readily Biodegradable

A compound that converts to 60% CO2 inside a 28-day study.

Inherently Biodegradable

A compound that converts to between 20% and 60% CO2 inside a 28-day study.

Non Biodegradable

Or ‘ultimately biodegradable’ is a compound that converts to less than 20% CO2 inside a 28-day study.

What are the Benefits for Customers and the Environment?

Testing a lubricant’s biodegradability can give you more knowledge about the behaviour of a product, how long it will take to decompose after use and how harmful it could be to its surrounding environment. Knowing this can help you comply with environmental legislation and standards, as well as satisfy your customer’s demand for more sustainable ways to run your network. Using a biodegradable grease is significant when you consider that rail networks are some of the world’s biggest landowners.


What is Bioaccumulation?

How bio accumulative a substance is can be measured by recording the speed at which an organism in a food chain can absorb and remove a toxic substance. In these scenarios, the organism is at risk of chronic poisoning if the foreign substance cannot be excreted quicker than it is absorbed. Therefore, the lower the levels of bioaccumulation, the better a product is for the organisms, species and wildlife in their habitats, and the wider environment.

How is it Tested?

A typical test for the bioaccumulation of a substance is OECD 105. This is measured by establishing its partition coefficient (expressed as log Kow) in octanol and water.

If a partition coefficient is low, then a substance will be unable to bioaccumulate as it will not leave any surrounding water for an organism to absorb. Any that did would leach back out quickly. If a partition coefficient is high, then a substance will also be unable to bioaccumulate as it will not leach out of the grease/oil/etc. and into the aquatic environment to be absorbed by an organism.

However, if the partition coefficient is somewhere between these two parameters, then it may have the potential to bioaccumulate, and further testing could be required.

These tests include OECD 305 (bioaccumulation in fish); in these scenarios, a substance is introduced into the water for some weeks and the concentration in the fishes’ tissues established after a set period.

What are the Benefits for Customers and the Environment?

Choosing a grease that is non bio accumulative means you are less likely to have an adverse impact on living organisms or their sensitive eco-systems. Ensuring the products you use do not build up in the environment over time is a critical part of ‘working sustainably’ to support your wider Environmental policies.


What is Acute Toxicity?

Acute aquatic toxicity is defined as the study of the effects of a chemical substance on aquatic species.

This is usually determined on organisms representing the three levels of the food chain, i.e. vertebrates (fish), invertebrates (crustaceans, such as daphnia) and plants (algae).

How is it Tested?

The preferred test is OECD 201 and determines the effects of a substance on the growth of freshwater microalgae and/or cyanobacteria. Test organisms are exposed to the test substance in batch cultures over a period of normally 72 hours and growth/growth inhibition is measured and assessed. The average growth rate during the exposure period is used to determine the concentration bringing about a specified inhibition of growth.

The ideal requirement for substances is a NOEC (no observable effect concentration) of >=100mg/l. The tests for fish and daphnia are OECD 210 and 211 respectively.

What are the Benefits for Customers and the Environment?

Curved rail grease will always end up in the waterways of the environment once it is washed off the rails, so using one that is low in aquatic toxicity is essential to reduce any environmental impact you will have on your surroundings. Your rail network will undoubtedly travel through sensitive areas such as national parks, over rivers and other waterways so this a very important aspect of any products you use that are released into the environment.


What are Renewable Lubricants?

Renewable lubricants are products featuring raw materials which can be used repeatedly and replaced naturally. In grease, vegetable oils extracted from seeds could be considered a renewable resource when compared with mineral oil. It’s also worthwhile noting that the CO2 released when a renewable material biodegrades will be absorbed by the next crop growing, so the ‘cradle to grave’ CO2 emissions of a high-renewables grease are much lower than a traditional petrochemical grease.

How is it Tested?

Typically, the renewable carbon content of a component will be measured.

The ASTM D6866 is an effective way of determining the bio-based content of a substance, and tests for carbon-14 will determine its carbon source. Carbon-14 is generated in the atmosphere by high-energy cosmic rays and has a half-life of 5,600 years.

Any substance which is millions of years old such as oil or coal will have no carbon-14 left. This means the proportion of carbon-14 detected in a sample will reveal how much is from a fossil source and how much from a renewable.

What are the Benefits for Customers and the Environment?

Utilising renewable sources for greases takes the pressure off our rapidly depleting non-renewable resources such as crude petroleum oil. If you are reliant on fossil sources, they can be harder to source and more expensive to buy while having low biodegradability and high toxicity. Adopting renewable sources is not only better for the environment, it helps achieve sustainability commitments and can also be more cost-effective over time.


RS Clare's Rail Eco Credentials

RS Clare prides itself on developing incredibly high performing curved rail, environmentally friendly greases that are specially formulated to meet the most stringent environmental standards and carry the much coveted EU Ecolabel. Click on the link below to view our EcoCurve range and decide if this is something that is right for your network and your local environment.

The European Ecolabel is recognised throughout Europe and worldwide as a label of environmental excellence.

The EcoCurve Rail Range


Customer Feedback

“Switching to RS Clare EcoCurve Trackside has made a huge difference, especially in the summer months because the old grease was almost turning to water in summer and did not stick well to the rails so we would use much more grease. Our lubricators are now more reliable and we’re realising significant cost savings, all while protecting the environment.”




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