found this on FAQ oh well, read, read then read some more.
25. Should I patch cracks/holes/mortar joints prior to coating. How would I do this?
Epoxy-Coat recommends patching all cracks prior to coating. Due to the fact that mortar joints/saw cuts are engineered for movement Epoxy-Coat does not recommend patching them prior to coating. All holes larger than ¼” should be patched prior to coating. All cracks can be patched (12 hours prior to coating) with a flexible, adhesive (paintable) acrylic caulk. Epoxy-Coat sells this product or you can purchase it at your local hardware store. Simply caulk the cracks and remove the excess with a tape blade. Holes larger than ¼” can be patched by Epoxy-Coat. Epoxy-Coat is 4x stronger than concrete so it is perfect for patching. You can patch holes or rough concrete in 2 different ways:
1.Apply Epoxy-Coat in a normal application. Do not back-roll in the rough/hole areas. This will only work on rough areas or holes which are not throughout the concrete (so the coating will not sink through the concrete when patched).
2.Mix Epoxy-Coat with a fumed silica (available through Epoxy-Coat), this will give a thicker viscosity and can be used to patch any and all rough areas/holes/joints at any thickness or size. Epoxy-Coat will have to be applied after this patch work is complete