Introduction to the Refractive Factor

Written by: Kent Ayers;  Johnston’s Coolant Specialist

Coolant Specialist, Blaser Swisslube, Kent Ayers

Most of Blaser Swisslube’s coolants have a refractive factor of 1, it can sometimes be easy to forget the significant impact a refractive factor can have on overall coolant costs.  Recently, we were challenged by a customer, to explain how a refractive factor works in terms that were easy to understand.

Step #1 – The Refractometer

In basic terms, a refractometer is a tool used in metalworking to measure the amount of oil in the coolant.  It uses the Brix scale to measure the concentration of oil based on the degree to which light is bent as it passes through the coolant solution.  This handy tool is vital to machinists as well as to those who sell coolant.


A refractometer from Blaser Swisslube

Step #2 – The Refractive Factor

As mentioned, most of the Blaser Swisslube coolants we sell have a refractive factor of 1.  That means that if you read 10% on the refractometer holding a sample of BC 940 (refractive factor of 1), then 10% of that coolant started out as coolant concentrate, while the other 90% is water that was mixed with the concentrate  to make your coolant.

It is when a refractive factor is greater than 1 that things can get confusing.  Some coolants may have a refractive factor of anywhere from 1.5 to 3+.  For simplicity’s sake, let’s look at an example where the refractive factor of a coolant is 2.  When you look into the refractometer of the coolant sample and it reads 10%, it means you are looking at a coolant sample that is basically equivalent in terms of the volume of oils and or emulsifiers contained in the sample the sample of BC 940.

However, because the refractive factor in this example is 2, you can multiply the refractometer reading times two in order to see the actual amount of coolant concentrate that was used to arrive at a 10% reading.

Step #3 – The Application (The Difference It Makes)

Continuing our illustration, let’s say that we are going to fill two identical machines with coolant.  Each machine has a sump that holds 100 gallons of mixed coolant.  The target concentration for both machines is 10%.

The machine using Blaser Swisslube BC 940 will is filled and the refractometer reads 10%.  Since the refractive factor of BC 940 is 1, we know that the amount of concentrate that was pulled out of the drum to make up the 100 gallons of mixed coolant is 10% of 100 gallons or 10 gallons.

On the other hand, the other machine has been filled with 100 gallons, and the refractometer reads 10%.  However, the refractive factor must be applied to the equation to determine how much concentrate was pulled from the drum to mix coolant for this machine.  So, in this example, we multiply 10% times the refractive factor of 2 which equals 20%.  20% of 100 gallons equals 20 gallons of concentrate from the drum that was required to mix coolant that reads 10% on the refractometer.

The Moral of the Story

This illustration provides a simple example how much more important value delivered is vs. the price per drum of coolant.  Because of the difference in the refractive factor, the Blaser coolant in this example will yield twice as much daily top-off coolant as the competition.  When price is used as the determining factor, it is easy to miss out on an opportunity to experience the positive improvements you can experience with Blaser Swisslube, the Liquid Tool.