I am using WS Realistic Water for the first time to model a lake and river. All went well with the pour, but as it is drying it is developing lots of cracks that come in from the edge towards the center. Base is pink foam carved to depth, sealed with plaster well, acrylic paint. These are not bubbles - they are cracks. Has anyone had this experience? WS suggests that their product does not crack, but suggests using denatured alcohol to soften cured product to fix defects. Any help would be greatly appreciated.