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Collection Care: Data Loggers and Hygrometers

The importance of collection care cannot be underestimated which is why Willard Conservation are pleased to offer a range of high quality environment/data loggers and hygrometers from our partners at Rotronic.

Rotronic is an international development and manufacturing company that offers a wide range of products for measuring and monitoring relative humidity, temperature, CO2, differential pressure, pressure, flow, dew point, and water activity. Below are two products from the range Willard currently offer. The view the full range, click here.

Rotronic Sword Hygrometer GTS

hygrometer sword, conservation

The GTS Hand Held Sword Hygrometer is easily insertable for measurement between layers of paper, textiles and other difficult to monitor materials. This is a stand-alone unit with a fixed probe and clear, uncluttered display for quick and accurate checking of stored items and exhibits.


  1. Thin, rigid aluminium blade, 420mm

  2. Range of application: -10 to 60 °C and 0 to 100 % rh

  3. Specified accuracy at 23°C (±5 °C): 1.5 % rh and 0.3 °C

View the full product listing here.

Rotronic HL-20D Data Logger

temperature and humidity data logger, conservation

This data logger offers very high precision (0.8% RH and 0.2 °C) at a good price. A stand alone data logger can be used in a variety of locations to reveal environmental fluctuations in storage and display areas. The unit can be deployed not only to monitor general conditions, but can also be placed in more confined, temporary locations for example, inside storage systems. The high accuracy of this unit can be used to assist the conservator and curator to determine the efficiency of heating, ventilation and air conditioning systems in maintaining desired values.

Downloadable loggers can complement wireless systems, which are often placed in fixed locations to provide long term data. They can also be used in remote stores and historic buildings with minimal set up time. The internal memory can store up to 32,000 data points and battery life is up to 3 years. HW4-Lite programming and analysis software and data cable included.


  1. Specified accuracy at 23°C (±5 °C): 0.8 % rh and 0.1 °C

  2. Elegant, unobtrusive design

  3. Excellent sensor stability

  4. Long battery life

  5. Range of application: -10 to 60 °C / 0 to100 % rh

  6. Uncluttered LCD display

  7. Programmable recording intervals

View the full product listing here.

Discover the full range of environment/data loggers and hygrometers, here.





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