There are two possible reasons for this happening. The most common reason is you've forgotten to warm up and shake up your Part B of Flex-Tec before you mixed it with Part A.
If Part B of Flex-Tec is allowed to sit for any length of time the material will begin to crystalize and separate. For adequate adhesion, you will need to warm Part B to clarify it and vigorously shake the Part B to fully homogenize the mixture before adding it to Part A. If you do not shake Part B to mix it, your final coating will not fully cure.
The second possible reason is that you've been spreading, moving around or otherwise still moving the Flex-Tec around on or in your piece after the 15 minute Pot life.
The Pot life is deadly serious in its timing. After 15 minutes of application, the Flex-Tec will want to be left alone to begin curing. Do not continue to move the mixture around or paint it around or otherwise mess with it or the curing will not successfully begin and you'll be left with a goopy mess that you'll have to clean off and begin again with.
Apply your Flex-Tec within 15 minutes of it's mixture and then leave it alone to begin the curing process and you'll be fine.
Please follow the curing process as closely as possible for best results.
If you find that you need extra time to work with the Flex-Tec on larger pieces, we also now have an extended work time formulation of Flex-Tec that gives you an hour of working time on the material before it begins to set.