We evaluated limewashed brick samples before and after artificial weathering using visual appearance, abrasion testing and adhesion testing. Test results are represented as an average of the results from the individual samples for each wash. Three replicates were prepared for each wash. Individual results for each sample are recorded in the appendix that is included with the report. A ranking system was devised in order to evaluate the results of each test. Based on their performance, we ranked each limewash from best to worst for relative change in appearance, adhesion, and abrasion for samples both before and after weathering. Those with the best performance ranked a 10 and those with the worst performance ranked a 1. The rankings were then totaled for each wash, creating an overall ranking.
For unweathered samples, washes F, H, and D performed the best in adhesion testing. This means that washes F, H, and D bound most tightly to the brick prior to weathering. Upon abrasion testing, unweathered samples of washes A, B, and K performed the best. This means that they formed a harder coating that was more cohesive.
After artificial weathering, each wash was visually evaluated and we found that washes A, E, and K performed the best, although all of the washes performed very well. Washes C, E, and G performed the best in the adhesion test of the artificially weathered samples with no variability in any of the results. Wash K also averaged the same rating as the best performers, but there was a large standard deviation. Washes A, B, and D performed best in the abrasion test on the weathered samples although washes A and B performed almost twice as well as wash D.
For the handmade brick the three best performing limewashes were washes A, E, and K. Limewash A is Graymont’s Ivory hydrated lime, table salt, alum, unsulphured molasses, laundry bluing, and water. Wash A performed the best in the abrasion test both for the unweathered and artificially weathered samples. For the abrasion test of the samples that were not weathered wash A averaged 93 liters, almost two times greater than the next best performing wash B and three times greater than the third best performing wash K. For the abrasion test on the samples that were weathered wash A also performed the best with an average of 8.25 liters that had a small standard deviation. For the adhesion test on samples that were not artificially weathered it performed in the middle of the group and towards the bottom of the group for samples that were artificially weathered.
The second best performers on the handmade brick were washes E and K. Wash E is Graymont’s Niagara lime putty, unsulphered molasses, laundry bluing, clove oil, and water. It performed equally with A and K as the best that were artificially weathered and equally with C and G as the best in the adhesion test on the samples that were artificially weathered. In the abrasion test on the samples that were artificially weathered wash E performed in the middle group. For the samples that were not weathered wash E rated as the fourth best in the adhesion test and as the third worst in the abrasion test.
Wash K performed equally as well as wash E. Wash K is the Virginia Limeworks lime putty and water. For the artificial weathering wash K was grouped in the best rating with washes A and E. For the rest of the tests it ranked in the middle group when compared with the other washes. Wash K is still considered a good performer despite it ranking in the middle of the group in several tests where a few washes far exceeded the others in performance such as the artificial weathering.