Understanding the Effects of Temperature and Humidity on Rubber Hardness


In the world of rubber and elastomer materials, maintaining optimal performance is crucial. One of the key factors that significantly impact the properties of rubber is its hardness. The hardness of rubber determines its suitability for various applications, from automotive seals to industrial gaskets and beyond. However, depending on the formulation and polymer type, temperature and humidity can influence this critical property, leading to variations in performance. Let’s explore how these environmental factors affect rubber hardness, what measures can be taken to mitigate their impact and what instrument we recommend assisting a chemist’s understanding of humidity and temperature effects on rubber hardness.

Temperature: The Game Changer

Temperature plays a pivotal role in determining the hardness of rubber. As temperature increases, most polymers or rubber formulations tend to become softer. This phenomenon occurs due to the increased molecular mobility within the rubber matrix. Conversely, when the temperature drops, rubber becomes harder.

For instance, automotive seals and gaskets exposed to varying temperatures must retain their performance characteristics to prevent leaks and ensure safety. Understanding the temperature-dependent behavior of rubber allows manufacturers to select or formulate materials that can withstand specific thermal conditions

Humidity: The Silent Influencer

While temperature effects on rubber hardness are more widely recognized, humidity also plays a crucial yet often underestimated role which may have different effects. Rubber materials can absorb moisture from the environment, which may affect physical properties. Porous materials with open cell structures may have more severe effects.

High humidity levels can cause rubber to swell as it absorbs water, resulting in a decrease in hardness. On the other hand, low humidity conditions can lead to the drying out of rubber materials, causing them to harden over time. Both may have adverse effects on physical properties or performance of rubber materials.

Mitigating the Effects:

To ensure consistent performance, it is essential to consider both temperature and humidity during the selection and formulation of rubber materials. Here are some strategies to mitigate the impact of these environmental factors:

  1. Material Selection: Choose rubber compounds specifically designed to withstand the intended temperature and humidity conditions.
  2. Additives: Incorporate stabilizers and plasticizers that enhance the rubber's resistance to temperature fluctuations and moisture absorption.
  3. Protective Coatings: Apply protective coatings to rubber components to create a barrier against moisture absorption.
  4. Environmental: Controlling the ambient temperature and humidity can help maintain optimal rubber hardness.

Instrument Selection:HT-3000-Chamber_01

At MonTech USA, we have designed the HT 3000 Chamber to better assist the rubber chemist’s endeavors to understand humidity and temperature effects on their materials. The HT 3000 Chamber features an environmentally controlled chamber, enabling changes to the humidity and temperature exposed to each hardness button over the duration of the testing sequence.

The Shore or IRHD durometer heads extend into the chamber and are automated to sequentially read each button as the chamber dynamically alters humidity and temperature levels over time.

Test sequences may extend for large durations of time and across varied conditions.

Our state-of-the-art testing equipment and expertise ensure that your rubber materials meet the highest standards of performance and reliability, regardless of the environmental challenges they face.


Temperature and humidity are key environmental factors that can significantly impact the hardness of rubber materials. Understanding their effects allows manufacturers and engineers to make informed decisions when selecting and formulating rubber compounds for specific applications. By implementing appropriate measures, such as choosing the right materials, using additives, and applying protective coatings, it is possible to mitigate the impact of these environmental factors and ensure the consistent performance of rubber components.

Our state-of-the-art testing equipment and expertise ensure that your rubber materials meet the highest standards of performance and reliability, regardless of the environmental challenges they face.

For more information on our comprehensive range of rubber testing solutions, visit montechusa.com or contact our team of experts today.

Looking for an Environmentally Controlled Hardness Tester? Fill out the form below and one of our product consultants will design one with you.