I agree with Dale as well. I used to use a lot of caulking for unions, throats etc. Caulk does not solve or stop shrinkage. I began using other materials that set and glued things down BEFORE the skin dried. Caulk sets AFTER the skin has already dried and shrunk. I also replaced the cotton with chopped excelsior. Its more controllable/easier to shape from the outside where cotton is not.