Water in its gaseous state is composed of individual H₂O molecules. It’s fascinating to note that it takes approximately 1.36 trillion of these tiny molecules to form a single drop of water. An H₂O molecule measures about 0.000275μ, making it incredibly small compared to bacteria and mold spores, which are significantly larger and heavier. This means that humidity itself cannot carry these microorganisms due to their mass.
Molecular Attraction, Phase Transition and Misunderstandings
H₂O molecules have a magnetic field attraction (polarity): hydrogen carries a positive charge, while oxygen carries a negative charge. This magnetic attraction bonds the H₂O molecules together, forming water drops up to Ice. When the energy (temperature) of these molecules increases, they become more active and start to jiggle, breaking free from each other and transitioning from a liquid to a gaseous state.
The surrounding air temperature has a minimal direct effect on the liquid material. Simply warming the environment doesn’t guarantee moisture release from the material. The key is to raise the temperature of the material containing water, causing the water molecules to become more agitated and transition into a gaseous phase.
Place a pan on a stove (turned off) and put a drop of water in it. It takes a considerable amount of time for the drop to evaporate. Now, try with the stove turned on. The energy (heat) transferred to the water drop makes it jiggle vigorously, and within seconds, it evaporates.
The principle “Wet goes to Dry” can be misleading as it lacks precise measurement, leading to confusion among restoration professionals. Lowering the humidity ratio (GPP) does not necessarily result in rapid evaporation. This misunderstanding will cause inaccurate recommendations based on GPP readings, leading to inappropriate drying timelines.
A common misconception is that low grains per pound (GPP) or relative humidity (RH) indicate the absence of moisture. However, solely examining the air space temperature and RH is insufficient to conclude that the area is dry. GPP should be used to assess Grain Depression, which measures how much water vapor is being condensed. This information is critical for evaluating the performance of your dehumidification equipment or when it has gone from a dehu to a heater.
Thermal imaging cameras are valuable for documentation, but it’s crucial to go beyond showcasing temperature variations and capture the actual temperature of materials. Warmer materials (not in any drying phase) can amplify biological loads. For example, capturing affected material temperature along with exposure duration and ATP testing can provide a more comprehensive picture of potential biological growth. Not just a selling tool.
Vapor Pressure and Drying Phases
Consider a scenario where the air space temperature is 85°F with 34% relative humidity, and the material’s temperature is 50°F with 100% relative humidity. Using a psychrometric chart or app, you can calculate the vapor pressure (Vp) of the air space (0.3) and the material (0.4). This indicates higher pressure in the material and lower pressure in the air space, demonstrating the principle that high-pressure areas move towards low-pressure areas. Understanding these dynamics is crucial for effective restoration practices. However, there is a BIG issue to be aware of, which will be discussed in part 7.
A huge thing to know is the constant rate and falling rate phases are pivotal for effective restoration. During the constant rate phase, airflow from air movers expedites the drying process of surface water only. However, in the falling rate phase, excessive airflow plus heat can prolong drying times, potentially leading to material removal or premature equipment removal. Just like searing a steak can lock in moisture, too much heat for too long during drying can trap moisture inside the material. This is called case hardening.
To identify the transition, compare the material temperature to the air space temperature. If they are approximately the same or around a 2-degree difference, you’ve likely entered the falling rate stage. Another thing is your meter. Check the owner’s manual as it may differ, but generally, for wood materials, there is a specific number indicating fiber saturation. If the reading is above this number, it means the wood is in a state of fiber saturation, giving a relative reading. Once the reading drops below the specified number, it is no longer considered fiber saturation, and you are no longer in the constant rate phase when drying wood.
Luis Suarez
Luis Suarez is a seasoned technical educator and consultant with over a decade of experience in the Restoration industry. His journey in this field is marked by a passion for education and a strong commitment to helping others succeed.
As the founder and leader of RestorRight Bilingual Academy, Luis has created a dynamic platform aimed at advancing knowledge and skills within the restoration community. This endeavor was inspired and supported by Recovapro LLC, a prominent water and fire restoration company whose mission aligns with Luis's dedication to education and mentorship.
Luis's primary objective is to guide and mentor aspiring professionals in the restoration industry, helping them navigate the challenges that come their way. His immediate goal is to become an approved IICRC (Institute of Inspection, Cleaning, and Restoration Certification) instructor, enabling him to provide certification courses in both English and Spanish. This reflects his commitment to making high-quality training accessible to a broader, more diverse audience.
Beyond his professional pursuits, Luis is a loving husband and the father of two energetic youngsters who keep him on his toes whenever he's not furthering his own education.
Luis is eagerly anticipating the upcoming opportunity to travel across the United States, sharing his knowledge and expertise with students in both English and Spanish through IICRC certification courses. His journey in the restoration industry is marked by dedication, a passion for education, and a drive to make a positive impact.
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