The storm windows are now in and I have repaired a couple of sills with concrete that come in a tube that you use like a caulking gun. It is quick and easy but it is gray and my sills were a biege concrete. I had been planing to paint brown to give the window frames a seamless look. I used an alkyd paint that is perfect for concrete. The window renovation is a long process, as each pane of glass has to be cut individually by the glacier before Steve my handyman custom frames using wood instead of putty to give a very clean look.