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by Dom Ruggeri

October 2005:

As you must know by now, in the late 1980’s to early 1990’s I was working for a large formulating house servicing the metalworking fluid market.  I had finished developing a high-tech soluble oil and we were going into a field trial.  We visited the customer, completed our system survey, and saw no reason not to proceed with the coolant trial.

As I have said many times in the past, you hope this field trial will be interesting.  Yet at the same time, you are praying that you will be bored to tears.  If the trial is interesting, there were problems.  If it is not, then all went smoothly.  This time all went smoothly.  I returned to the laboratory and moved on to other projects, as luck would have it we get a call from the salesman telling us that the coolant was beginning to show a cream layer on the surface of the make up fluid.  I was stunned.  How could this be happening we checked everything, and why only in the make up fluid?  We went over the product from top to bottom we found nothing; as far as I could see, the emulsion should have been stable until the cows came home.  Yet here we are, the customer has a problem.

As always, we performed a painstaking analysis of each and every component of this new masterpiece.  Once again, to no avail; yet something was amiss.  We checked the product in distilled water, our tap water, the customer’s water, and RO water.  Each time the emulsion was perfect.  Once again we begin to question everything, but this time, one question comes forward: what temperature is the water when the product is diluted?  None of us knew.  We found out that the water temperature when the product was introduced into the central system was 45 degrees F.  We emulsified the coolant with water cooled to 45 degrees F and we reproduced the problem.  Therefore, water temperature at the time of dilution is more important then we ever imagined.

Last time we talked about different types of water and how it can affect your coolants.  Today I would like to spend the time discussing potential reactions between the make up water and your coolant concentrates.

Fatty Acid and Hardness:

Everyone knows that the harder the water the less foam, but few people know why.  The answer is the fatty acid package in your product reacts with the Calcium and Magnesium.  At times these salts will make a few great antifoams.  However, once neutralized, and depending on the fatty acid you used, the fatty acid calcium salt may be an ineffective antifoam (not all fatty acids make good antifoams).  Therefore, if you are testing a coolant in tap water and the water hardness is over 100 ppm and you are still getting foam, check the hardness of the emulsion using a water hardness titration.  

Some coolants will interfere with the hardness titration, therefore you must first check for this phenomenon.

1.      Using the hardness titration, check to make sure that your distilled waters actually zero hardness.

2.      Make up an emulsion of your coolant at the customer’s use level and titrate the hardness.

The coolant emulsion should read zero hardness.  If it does not, you have interference from a raw material and you can not use this method to check for a reaction between the Calcium and your fatty acid package.  Of course, if the water hardness is equal or above 100 ppm as CaCO3 and you are not having a foam issue, it is a safe bet that the fatty acid is reacting with the water hardness to make antifoam.

So if your coolant is being used in water >100ppm hardness and you are still having a foaming problem you have three choices:

1.      Use a Chemical Antifoam (modified silicone)

2.      Change your fatty acid package (not always possible)

3.      Adjust the fatty acid package until you bring the foam under control (Not always possible)

As always should you have any questions please feel free to e-mail me in care of the magazine.  Till next month,