Improvement of the image analysis method for quantifying low-polarity oily stains on fabric

The stain quantification method using image analysis is excellent because it is non-destructive and applicable for non-uniformly adhered stains. The technique is difficult to adapt to colorless stains, but can be used by coloring the stains. However, low-polarity oils have poor compatibility even with oil-soluble dyes, and it is difficult to accurately quantify them from the appearance. The purpose of this paper is to examine the quantification of low-polarity oily stains by three methods: (1) search for a dye tracer suitable for non-polar oil; (2) use an ultraviolet (UV) image by mixing a fluorescent tracer; and (3) use an UV image using a model stain that absorbs UV rays. In the experiment, the soiled samples were prepared by dropping soiling liquid on a cotton fabric and washing with a tergotometer, and the cleaning efficiency was determined from the image obtained with a digital camera. Results showed that Elixa Red 348 with lower polarity than Sudan IV and Oil Red O is superior as a dye tracer for non-polar oil. In the fluorescence tracer method, the sum of G values (Σ G) in the red, green, blue signals of the image data can be used, but the decrease in fluorescence over time is a problem in the case of pyrene. It was also found that UV-absorbing stains such as alkylbenzene can be quantified from UV images by utilizing the slight fluorescence coloration of cotton fabric generated under 254 nm UV irradiation. The future potential of image analysis methods for quantifying non-polar oily stains was suggested.