Flex Seal is an amazing product that can be used to seal just about anything. However, there are a few things that Flex Seal will not stick to. These include:
1) Teflon - This is a common coating that is applied to cookware and other surfaces to prevent sticking. Unfortunately, it also prevents Flex Seal from bonding.
2) Oil - Any type of oil, whether it's cooking oil or motor oil, will cause Flex Seal to bead up and eventually fall off.
3) Wet surfaces - Flex Seal needs a dry surface in order to adhere properly. If the surface is even slightly damp, the sealant will not bond as well and may eventually peel off.
4) Extreme heat - Flex Seal can withstand high temperatures but if it's exposed to direct flame or extremely hot surfaces (over 200 degrees Fahrenheit), it will begin to break down and lose its adhesive properties.