I have a "stucco" Tudor house. The "stucco" is cement board with a stucco pattern manufactured into it. A house painter two years ago "repaired" some water damage by cutting out small parts of the boards and piecing in new sections, and the "repairs" are much worse now than the supposed damage. It appears to be the mixture of stuff he used to cover the horizontal joint between the older piece of cement siding and the new small pieces of cement siding. The stuff is now wet and lifting up just like wet drywall would do. What is the identity of the correct substance that needs to be trowelled onto the horizontal seam between the two pieces of cement fiber siding to make them appear to be seamless? AS you can tell I know little about this but I need to educate myself so I'm not taken by another "professional" contractor. Thanks for any insight.