The economics of using bacteriostatic soluble oil

At the outset of the COVID-19 pandemic Flexilube realised the importance of their customers coolant systems whilst they were not being circulated. The company also took into consideration operator health, especially when the machines would be re-started. Flexilube immediately got to work on developing their new bacteriostatic coolant – BioKool Citrine.

In an interview with Sales Director Paul Linaker he said: “Conventional coolants could be considered a zoo for micro-organisms. To keep the zoo under control, manufacturers fortify emulsions against bacterial and fungal attacks. However, the chemicals used are expensive and require regular dosing to keep the coolant in tip-top shape.”

“What would happen if you could not maintain your zoo? Bacterial and/or fungal infections would usually follow. In the case of your coolant in your machine additional biocide dosing to bring infections back under control and we say biocide is, without exception, a toxic material.”

Flexilube have changed their 20 litre and 50 litre packaging to incorporate nine aspects of improvement to the packaging

“You would have a shorter coolant emulsion life that would result in increased disposal costs. There would also be retrogressive stability of the emulsion and this leads to poor performance.”

“Additionally, there would be corrosion (rust) and increased emulsion consumption due to retrogressive emulsion stability. There would also be higher consumption of coolant due to increased circulation times during downtime and a decrease in tool life due to insufficient coolant performance. All this results in non-productive machine tools and we all know what that means.”

“In addition to this, there can be further unpleasant side effects, such as a bad odour and skin eczema, which is sometimes called atopic dermatitis.”

“We have to ask ourselves whether we are able to combat bacterial growth without influencing the technical characteristics of the emulsion without having to use toxic biocides and without the possible growth of harmful bacteria?”

“In Europe a limit of 103 to 104 bacteria per ml has already been prescribed as law in Europe. Now in 2020, commercially available coolants have been neatly placed into the following three categories:

Condensation products
“Condensation products constitute the largest market share of commercially available coolants. The performance of these products is negatively impacted by microbial growth. To combat this, manufacturers add biocides to preserve their products. Biocides are frequently made from phenols or formaldehyde-releasing chemicals and these are harmful to humans.”

“New biocides have been introduced that are less harmful, however, these are sold at inflated prices and are very often misused without taking operator health into consideration. All things considered, even the best out there is still not good for your health.”

Biostable products
“Biostable products (also called low maintenance products) are those products whose performance is not negatively impacted by a bacterial infection. These products usually contain very little amounts of biocide allowing infections to grow uninhibited. With time, the bacterial count increases to 106/107ml (1 to 10 million bacteria per ml) without noticeably influencing the quality of the emulsion.”

“The problem with these coolants is that some bacteria release toxins that are also harmful to machine operator’s health. The use of these emulsions must therefore be questioned when considering health and hygiene.”

Bacteriostatic products
“Manufacturers of biostable coolants sometimes incorrectly equate their products to bacteriostatic products. Raw material selection synergy in bacteriostatic products limits bacterial growth up to a typical level of 103 bacteria per ml (100 to 1000 bacteria per ml).”

“Bacteriostatic coolants are the only types that meet the following requirements:
No bacterial growth harmful to one’s health.
No formation of by-products harmful to one’s health.
No reduction in product performance.”

“By using a well-designed biostatic coolant, considerable cost savings can be made because increased coolant life span limits disposal costs. In centralised systems, emulsions do not have to be circulated during downtime resulting in energy saving.”

“There is no ‘Monday morning smell’ and there is less emulsion usage due to consistent particle size of the emulsion. Additionally, there is no bacterial by-product formation (e.g. corrosion) and dosing with biocides or fungicides is eliminated in an optimum coolant environment.”

“Following the successful launch of our tried and tested BioKool Range, we asked ourselves what is next? After many hours of laboratory work, we developed BioKool Citrine.”

A graphical example of the three different types of coolants

“So, what is new in the new product from Flexilube? Some might say that this is just another name for a new iteration of our bacteriostatic technology. We emphatically say no!”

“BioKool Citrine expands on Flexilube’s current technology by becoming part of your cleaning staff. BioKool Citrine does not just run clean it cleans dirt and grime inside your sump, pumps, piping and all those difficult to reach places that never receives the cleaning they deserve.”

BioKool Citrine becomes your workshop’s air freshener. Who does not like the smell of fresh citrus in the morning?”

“And, by being mindful of your operator’s health and safety, BioKool Citrine produces far less mist than anything else we have previously introduced into the market. The bonus is that BioKool Citrine improves tool life and machine life. This ultimately adds to the bottom line!”

For further details contact Flexilube on TEL: 016 362 0343 or 082 655 9999 or mail your enquiry to or visit