A window is composed of the frame, sash, sill and pane of glass. Years of painting will often leave layers of paint on the sill and other areas of the window. Removing this paint on both the inside and outside of the window can present many difficulties. Always caulk the exterior aspects of a window to repair any damaged seals.
The three main power tools you may use to strip paint off a window sill include a handheld dremel, an electric sander or a planer. The dremel offers a variety of oscillating tips that can reach into smaller and more difficult to manage corners of the window. The electric sander will make quick work of paint as long as you start off with a coarse-grit sandpaper. The electric planer will shave off layers of paint, but use caution with this tool because it will remove wood if you push too deep. Quickly and easily remove paint from a window sill by first using a planer on the surface, followed by a sander to clean up and then finally a dremel for the fine details.
Handheld tools present the best option for removing paint from a window. Most handheld tools allow you to carefully scrape off the paint. A handheld planer is more controllable than an electric variation and makes removing paint easy without damaging the underlying wood, which commonly happens when using an electric planer. A scraper is a sharp tool that operates like a chisel, but is wide like a spatula. It is excellent at removing paint from stubborn surfaces. A painter's tool, also known as a 5-in-1, operates like a scraper but is more capable of getting into the corners. A good razor blade will also help to peel off layers of paint from the wood and window panes but use caution, the blade can cut too deep and gouge the wood.
Paint strippers are highly caustic and will burn your skin. A single drop on your skin feels like someone lit a match and put it out on you. However, these chemicals will remove eons of paint in seconds. Paint strippers destabilize the paint, making scraping the layers off easier. If using a chemical paint stripper indoors, make sure you have plenty of ventilation. Alternatively, a mixture of water and soap, or straight window cleaner, is effective at softening layers of paint for scraping. The mixture will not peel away the paint like a paint stripper, but is also non-caustic and will not cause you to choke if you smell it.