How hot weather can affect adhesive application

Here Darrell Tibbins, Director of Technical, explains how hot weather can affect adhesive application.

In warmer temperatures, you will see a noticeable change in the flow properties of adhesives. The product’s viscosity (its ability to resist flow) can decrease, with the adhesive becoming thinner than usual. This can impact the application of the product.

This is because temperature has an effect on the molecules of the adhesive, as it does with every other liquid. The warmer they are the lower the viscosity, the more fluid they are. The lower the temperature, the higher the viscosity, the more viscous they are.

The thinner adhesives can be more difficult to apply as it may spread too quickly which impacts the application and expected coverage. Adhesives should only be applied when the outside temperature is between 5-30°C, otherwise the desired coverage rates may not be achieved.

The outside air temperature when applying the adhesive will affect its cure-time – the amount of time for the product to achieve its full bond. Heat accelerates the chemical reaction rate, meaning the product will cure quicker. Apollo Roofing quotes information on data sheets at 20°C.

Higher temperatures can also decrease the open-time of adhesives, meaning there will be less working time. Please be mindful to adjust working times accordingly.

As a general rule, every 10°C increase in temperature reduces the reaction time by 50%.

How to maintain the performance and ease of application of an adhesive during warmer months:

• ☀️ Store the adhesive in a cool, well-ventilated covered area, between 5-25°C.
• ☀️ Do not leave the adhesive outside in direct sunlight.
• ☀️ Keep only the materials that are planned to be used on that day on the roof.
• ☀️ Always check the adhesive before use.
• ☀️ Do not use the adhesive if the ambient temperature is above 30°C.

More information on using adhesives in warmer weather can be found in our Summer Tips blog.