The clot is depending on the stock of environmental humidity. CS flake is easy to absorb water. The lot no of FPC CS-F was 20150325/20150326 , FPC made on March 25/26th . Could you inform when you found the clot? If you found lately. The cargos already deposited on your stock around 3 months. If the weather was raining around April- June. Even FPC CS-F was gotten wet in the rain, it was easy to happen clot problem.
If CS-F didn’t have pollution by other chemicals , we think it still can keep quality. If it is only clot problem, you can use hammer to split it .it can restore original form and easy to deliver.
If you still have problem, don’t hesitate to inform us.