A Case Study on the Top Coating of Multicolor Painting Work Based on the Empirical Method

In multicolor painting for interior and exterior building finishes, a topcoat is often applied to protect the surface. Because topcoats are transparent, it is difficult to confirm whether one has been applied visually. However, Korean courts use empirical methods to determine whether topcoats have been applied in housing defect litigation. Typical empirical methods include observing gloss and assessing water-repellent properties. Pencils, water-based pens, and computer pens are used to assess graffiti-prevention properties. However, these empirical methods rely solely on appraisers’ experience and visual inspection, lacking standardized methods or detailed criteria. Furthermore, it is not even known whether each empirical method produces identical results. This study aimed to identify these inconsistencies by applying and comparing all known empirical methods to physical buildings. After assessing four locations in two apartment complexes, gloss was not found in any of the cases. The water-repellent and pencil tests showed a correlation coefficient of −1, demonstrating exactly opposite trends. The water-based pen test showed a correlation coefficient of 0.745 for black and blue, but none for red. The computer pen test results differed significantly from the other tests, and no correlation was found. These findings confirm that current empirical methods for detecting a topcoat in multicolor painting are inconsistent and should not be used.