Water-based defoamers are highly effective at controlling foam in many circumstances. However, in high-temperature processes, their performance can vary depending on the exact conditions and the specific formulation of the defoamer.

The effectiveness of a defoamer is not solely dictated by its base (oil, water, silicone, etc.), but by a combination of its ingredients and their interaction with the medium they are added to. In high-temperature processes, certain aspects of a water-based defoamer, such as its volatility and stability, could be negatively affected. As the temperature rises, water in the formulation evaporates, potentially destabilizing the defoamer and diminishing its foam-controlling abilities.

However, advanced water-based defoamers are specifically designed to withstand higher temperatures. These formulations include special additives, like certain polymers, which enhance the product’s heat resistance and functionality in high-temperature environments.

But, it’s important to note that silicone-based defoamers are often a preferred choice for high-temperature applications due to their superior heat stability and low surface tension, which allows for better spreading in foaming systems and enhances their foam knockdown efficiency.

In conclusion, while water-based defoamers can still be effective in high temperatures, one must consider the process conditions and the specific properties of the defoamer. Ideally, you should work with defoamer suppliers or technical experts to select the most suitable defoamer for your needs and make adjustments as necessary to ensure optimal performance.