My existing seam compound has had it. It is falling out all over the place. It is a dark colored, hard, brittle material that is easy to reef out.
What I bought to replace it is Interlux white seam compound for above the waterline. The instructions sound simple enough, but the first seam I did doesn't look very good. The problem seems to be it is very visible, and I thought the ideal look was a seam that is practically invisible.
Do I just apply it with a putty knife, as the instructions say, and strike it off like a mortar joint? or should I expect to sand it smooth after it dries? That first seam I did never dried hard, so it never got to what I would think is a sandable state.