Favorite Seam Sealer
I do inside to avoid having sticky wax on outside catching dust, pollen, fuzz and such. The thread should swell over time to stop moisture but if it hasn't yet it might never.
I did use seam sealer two units ago an was very disappointed. I went by manufacture instructions and the stuff was awful. Used it on outside and it left a shiny film on seam with a white tinge. To make it worse it didn't seal well at all. So now I do paraffin on inside. Works, stays hidden, easier to reach.