Things You'll Need
Sanding sponge or sandpaper
Sprayer or stain brush
Clear protective finish
Andersen windows are available in a wide range of styles. Most are weatherproof vinyl clad on the exterior, and the interior window surfaces are bare wood, ready to accept stain or paint. Andersen windows can be finished with oil-based, acrylic or gel stains using a high-pressure-low-volume sprayer or by hand with a brush. After staining, they should be coated with urethane, lacquer or some other clear protective coating for maximum color protection and durability.
Remove the window sash, if you have Andersen double-hung removable windows. The method will depend on the style of window, but typically the windows have plastic clips on the interior side. Push these down and secure them, and the upper portion of the window will slide out.
Remove window-locking hardware and window pulls with a screwdriver. Put the hardware in a bucket, or somewhere safe, so that you don't lose the screws.
Sand the wood with a sanding sponge or 120- to 180-grit sandpaper, working with the grain of the wood. Remove fingerprints, mill markings and rough edges. Dust them off with a soft brush.
Choose your application method. If you are spraying the windows, mask off all adjacent areas to protect them from over-spray. Most people will choose to stain the windows with a brush--it doesn't take very long. Use a natural bristle brush if you're applying oil-based stain and a synthetic brush for applying acrylic (water-based) stain.
Apply a pre-stain sealer. While this isn't a necessary step, Andersen strongly recommends it for an even, attractive finish. Follow label directions for drying time.
Mix the stain thoroughly, and apply it with a sprayer or brush. Don't worry about getting stain on the glass or weather-stripping. Stain one window at a time, and wait 10 to 15 minutes for the stain to penetrate. Wipe it off with clean, lint-free rags, turning them frequently and cleaning stain from the glass and weather-stripping at the same time.
Finish the stained windows with a clear protective coating. Make sure that whatever you choose is compatible with the stain, and follow label directions for application and drying times.
If your Andersen windows have grilles, they should be removed for staining. Sand and clean them, and then stain the wooden (interior) side. Before the stain dries, flip them over and clean excess stain from the exterior side with a clean rag dampened with mineral spirits.
Work in a well-ventilated area or use a fan to dissipate fumes, especially when applying oil-based finishes and lacquer. Be careful not to scratch the glass while sanding--you can permanently damage tempered or tinted glass.