Flex Seal is a versatile and effective product that can solve a multitude of household problems. However, it’s important to understand its limitations in order to avoid potential issues. In this article, we will explore the materials and surfaces that you should refrain from using Flex Seal on. By understanding what you should not use Flex Seal on, you can make informed decisions and ensure the best possible outcomes for your repair projects. So, let’s delve into the list of materials where Flex Seal is not your best solution.