Hello! My name is Marissa Bartz and I am a new Research Associate here at NCPTT. I have a Bachelor’s degree in Chemical Microscopy and a Master’s degree in Art History. Furthermore, I have had several internships in a variety of art conservation specialties, including paper, book, ancient textiles, metal objects, and 3-D scanning. I am very excited to dip my toes into the new waters of cultural heritage preservation!
I am continuing the project started by Lucy Midelfort and continued by Elle Farias and Silvia Lob (see their blog posts for more information). The objective of this project is to test five commercial anti-efflorescence products in order to determine which of them works the best in preventing efflorescence without damaging or changing the overall appearance of the substrate, which in this case, are bricks and brick walls. I will be finishing the two experiments designed by Lucy. One tests the products on five brick walls that will be aged with driving rains. The other tests the products on brick coupons that will be aged with artificial Q-UV. These methods of aging were chosen to best simulate worst-case conditions that can occur for different buildings not only in the National Park Service but across the United States.
Today, I will discuss the Water Absorption or Rilem Test that I performed on all seven of the test walls. The goal of this test is to measure the volume of water absorbed by a material within a specific time period. I completed this test after all the walls had cured with the products for at least a week, but before the driving rain cycles in order to understand how the product affected the water absorption of each of the walls.
The materials needed to perform this test are a water absorption test tube or a Rilem tube, a stopwatch, plastic cement, and laboratory washing bottle filled with water. First, I rolled a thin piece of plastic cement and placed it on the lip of dome of the tube.
Once the cement was placed securely on the tube, I chose a place on the wall to adhere it. However, before I placed the tube against the wall, I cleaned the spot with a brush in order to help the cement adhere to the wall. After a spot was chosen and cleaned, I firmly pressed the tube against the wall until the cement had evenly attached to the wall. Then, while holding the tube, I filled it to the zero mark using the laboratory wash bottle and pressed start on the stopwatch.
I timed how long it took for 1 mL of water to be absorbed into the wall. I did this three times at three different locations on each of the walls in order to have a good overall view of the water absorption of each wall. The three locations that I chose were somewhere on the bottom, middle, and top of the wall.
However, as the saying goes “the best laid plans of mice and men often go awry,” meaning although I did my best to account for all the variables in this experiment something unexpected happened. On several of the walls 1 mL of water was not absorbed even after I held the tube against the wall for two hours. Therefore, I decided that the two hour mark was the cut-off and I recorded how much water was absorbed in that time frame. Sometimes it was difficult to tell if the water was actually absorbed into the wall or just evaporated in that two hour time interval. For the walls that had the two hour cut-off, I only took three measurements total for the wall instead of averaging three at each location, since it seemed that the results were consistent across the different locations. Furthermore, I noticed on the walls that did not readily absorb the water; the ring of water from the tube was still there a few days after the tests were performed. The water appeared to be sitting on the surface of the coating instead of going into the wall. These observations are very useful in characterizing each of the anti-efflorescence products.
Well, folks that is all I have for now, but I shall post again soon!