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Chemtool Incorporated
801 West Rockton Road, Rockton, IL 61072
Telephone (815) 957-4140 | Fax (815) 624-0292


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801 West Rockton Rd.
Rockton, IL 61072
(815) 957-4140

Chemtool Blog

Problems introduced by sulfonates in commercial coolants

Posted by Chemtool Team on July 3, 2018

problems with sulfonatesIt’s possible you don’t even know you have a sulfonate problem.

After all, sulfonates have been included in metalworking fluids for decades. Admittedly, they’ve been around so long because they’re good at what they do.

Let's look at why they’re used, why it's time to move on, and why advanced chemistry more than makes up for their absence.

What are Sulfonates?

Sulfonates are the metallic salts of sulfonic acids. They’re structurally much like sulfuric acid except that one component has been replaced with an oxygen-hydrogen bond. They’re mild and soluble in oils.

Sulfonates are surfactants, meaning they reduce the surface tension between different liquids.

What do sulfonates do?

Sulfonates fill a number of roles in metalworking fluid, or MWF. Some are detergents or dispersants, keeping foreign substances in suspension. Others are corrosion inhibitors. Some are emulsifiers, keeping oily substances in water solution by keeping their particle size small.

Another type is the extreme pressure additive. Today’s machining processes can reach 200,000 PSI. To deal with these enormous forces, some metalworking fluids contain a sulfonate designed to adhere to the surface of the workpiece as a lubricant layer.

The problems with sulfonates

So, it seems sulfonates are worth keeping around. But they have three main drawbacks. Two are related to operator acceptance and the other is economic.

First, sulfonates are a contributor to Monday morning odors, including one particular stench. If bacteria take hold, they break down available sulfur compounds and release hydrogen sulfide. That’s the source of the rotten egg smell that can greet your operators in the morning. Note that if your MWF is being broken down, it’s not just an operator acceptance issue, but a fluid maintenance issue that must be counteracted at the cost of time and money.

Second, numerous studies have found sulfonates are often the MWF ingredient which causes the most irritation. For example, scientists studying an MWF with several additives found that one in particular, sodium petroleum sulfonate (a common corrosion inhibitor) caused pulmonary irritation after only 30 minutes, compared to 2 or 3 hours for each of the other ingredients.

The exposure levels your worker's experience are far below those needed to cause serious health damage. However, sulfonates irritate and damage the eyes and lungs and act as skin sensitizers. The damage is reversible, never life-threatening, and requires frequent exposure, but any health consequence is a bad deal for employees and for you.

Third, using a sulfonate-reliant MWF means you’re using outdated technology. These fluids may have a lower per-gallon cost than state-of-the-art products, but they simply don’t perform as well.

The answer

The latest generation of metalworking fluid, such as our line of NuSol semi-synthetics, feature highly advanced chemical engineering to accomplish the work of sulfonates (and more) without any of their drawbacks. That means no odors and improved operator acceptance. Though they may have a higher per gallon cost, they produce a lower per piece cost as you spend less on fluid management and worker protection/injury costs. They also deliver the best features of the previous generation of synthetics and semi-synthetics: Bio-stability, high lubricity, less tendency toward sticky residues, no-hassle maintenance, and minimal foaming.

If your fluid works better in the machine, it’s better for your operator and requires less time and money to use effectively, won’t that improve your operation?