by Colleen McFarland Rademaker

Everywhere in the Northern Hemisphere, the familiar harbingers of summer are emerging. In Bethany, the sun shines brightly as we begin and end our workdays at the Historical Society. The hummingbirds have returned, busily darting from blossom to blossom. The Campbell Mansion lawn is once again a plush, verdant carpet. And the rising humidity, manifest in our dewy skin and frizzy hair, ushers in this season of expansive abundance. 

What does the arrival of summer and frizzy hair have to do with the work of the Historical Society?  More than you might expect! The bulk of our historic Stone-Campbell movement collection consists of organic materials. Paper is made of wood pulp, linen, or cotton. Books are bound in paper or leather. Historic textiles are made of natural fibers, like wool, linen, cotton, and silk. Changes in temperature and humidity affect historical collections physically and chemically, much like they affect our hair and skin. The greater the swings in temperature and humidity, the greater the strain on collection material. Stewards of historical collections must actively measure and manage the temperature and moisture in the buildings housing those collections. 

The Historical Society began its environmental monitoring program in 2016, when the collection was moved to Bethany. Archivist Shelly Jacobs purchased several data loggers to measure and record the temperature and relative humidity in the collection preservation wing of the building. Working with the Historical Society’s HVAC service providers, she ensured that the temperature and relative humidity were largely maintained between the desired ranges of 68-72℉ and 40-55% RH. 

In April 2025, we replaced the data loggers with a wireless environmental monitoring system. Contracting with Conserv, we placed multiple sensors, including water detectors, in our preservation wing and offsite storage facility. The Conserv Cloud app allows us to view temperature, relative humidity, and other environmental data in real time via our smartphones. It also alerts us to water leaks and extreme conditions so that we can quickly take action by moving or covering endangered collections with plastic sheeting, requesting emergency HVAC service, or placing portable fans and dehumidifiers in collection storage areas. 

The app also supports the analysis of environmental conditions over time. Through automated weekly reporting, we receive data about our HVAC’s ability to maintain the desired temperature and relative humidity ranges. Customizable graphs and charts also help us identify and understand long-term patterns and trends in our storage environments. That knowledge will help us identify ways to improve the environment and recognize unusual readings that suggest a problem with a building or HVAC system. 

With Conserv’s monitoring system, the Historical Society enters the summer with increased capabilities and confidence in its environmental monitoring program.  If you would like to improve the environmental conditions in which you store historical collections, here are some tips: 

• Store collections in a room that has relatively steady temperature and relative humidity year round – ideally a room not adjacent to an exterior wall
• Use portable humidifiers and dehumidifiers to mitigate extremes in relative humidity
• Use portable fans to move warm or cool air as needed mitigate extremes in temperature
• Remember that providing stable temperature and relative humidity is more important than maintaining a specific temperature or relative humidity. In other words, a collection environment that consistently provides a temperature of 75℉ and 60% relative humidity is better than an environment that fluctuates between 60-70℉ and 40-55% relative humidity.