By the time you notice the fog and condensation, there could be several cups of water in the desiccant. If we were able to remove the desiccant from the window, it would take 4 hours in a conventional oven at 200 degrees to dry. However, the air space in a window only heats up to 170 degrees, so the dessicant can only dry to about 80% in the first month. In the second month, we return to install our proprietary UV resistant membranes which allow the window to breathe and continue expelling the moisture. The window may refog with temperature fluctuations, but it will be less and less each time. Once dry it will stay dry.