I am in the process of preping my home for paint on the exterior lap siding. I have replaced several sections of siding. My question,? is there such a product used in the for filling cracks at the butt joint of siding. My Son inlaw told me of a home improvement program he watched where they had used a wax ( ? parafin wax ) for caulking butt joints and genral cracks in wood. Is this true that there is a wax product to do just this type of repair. He explained to me that the program he was watching said that wax was a good caulking for this type of butt joint seal, as it will not melt leaves a good flexible joint that won't crack with the expansion and contraction that occurs with wet to dry warm weather.