Terg-o-tometer detergency evaluations with an improved reflectance method in warm versus cold wash temperatures

Abstract: Laundry cleaning tests carried out by our company in past decades used radiotracer labeling of a soil. This involved the application of a known weight of radioactive soil on a fabric swatch, washing it, measuring the wash water for radioactive material, and, finally, relating it back to quantity of soil removed.

The main objectives/findings of this paper are:

• First: Evaluate a commercially available Terg-o-tometer with new reflectance measurements to simulate the laundry washing process. A state-of-the-art color analyzer instrument was used as an alternative to the radioactive method to measure soil removal. The results obtained with the new detergency method (in terms of precision and discrimination) show that it can substitute for the radioactive soil method.


• Second: Compare soil removal at cold and warm water temperatures in line with the energy conservation drive for lower temperature washing. Lower temperature washing will likely require some reformulation of existing detergents.


• Third: Examine the efficiency of alcohol ethoxylates and alcohol ethoxy sulfates based on C11/13/15 and C12-15 modified-oxo alcohol blends with the same average molecular weight. This shows that they give similar detergency results suggesting they can substitute for one another.

Tests were carried out on surfactant solutions plus several off-the-shelf detergents, at 15°C and 30°C, to determine how temperature affects detergency. Fabrics swatches of polyester/cotton blend at 65%/35% with soils of meat-gravy and dust-sebum were used, two commonly used industry standards. Some preliminary tests including ballast fabric, to better simulate a washing load, were carried out.

This paper will add to the industry knowledge to digitalize and modernize laboratory cleaning test methods including at cold water conditions. It describes replacing a radiolabeled soil methodology, with HSSE and limited availability of different soils disadvantages, with a modern and convenient reflectance method that can be applied to a multitude of different soils.