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How to Repair and Repaint Old Window Sashes

Learn techniques for repairing and reglazing old windows.

More in Windows Walls and Doors

repairing windows in craftsman style cottage

Step 1: Remove Damaged Window Sashes

Score the paint joint between the wooden interior stop and the window jamb. After easing the interior stop away from the jamb, use a pry bar to pull it off completely. The goal is to remove it intact. Old houses were built of excellent long-lasting materials, so your objective may be to save as much as possible.

Place the sash on a suitable work surface so that they can later be reinstalled.

place sash on suitable work surface

Step 2: Remove the Old Glazing

To remove the old glazing, use a deglazing tool (Image 1), a specialized chisel with a pilot bearing on the back side. The bearing can be adjusted for cutting the precise depth required for removing the amount of glazing present. The tool is held at about a 45-degree angle to carefully remove the glazing bit by bit (Image 2).

Note: An infrared paint-removal system can also be used in this application to simplify removal of old window glazing. The infrared tool is used to heat up the glazing so that it softens, taking on a clay-like consistency. In this soft form, it can then simply be lifted out rather than having to chip or scrape it.

Step 3: Remove Paint with Specialized Tool

Strip the old glazing and paint as required to remove the old glazing points -- small pieces of metal placed every six inches or so in the frame to hold the glass firmly to the sash. The points are covered by glazing compound. The sharp tip of a paint scraper can be used to carefully remove the points without damaging the glass.

Remove the original glazing points and then carefully remove the glass from the sash. Clean and store it for reuse.

With the glass removed, used an infrared paint remover, which uses infrared heat, at relatively low temperatures, to soften and loosen the old paint. The process causes the paint to separate from the wood so that it can easily be removed using a paint scraper. Aside from making the job of stripping paint faster and easier, this system is designed to be safer and more environmentally friendly than traditional methods. There is less chance of generating harmful fumes (as when a heat-gun is used) or paint-dust (as can be the case with "dry-scraping" and sanding). This can be specially important when removing old paint that may contain lead.

remove paint with specialized tool

Step 4: Sand and Prime the Sash Surface

Clean and sand the sash surface. Scrape the glass channel completely clean. If necessary, apply polyester-resin wood filler to any rotted areas. Allow it to cure according to the manufacturer's instructions, then sand smooth. Prime the applicable faces of the sash with an oil based primer.

Step 5: Add Glazing Inside the Sash Frame

With the old paint removed, and the wood cleaned up and repainted, prep the sash before the old glass can be put back in. A back bedding of window-glazing that will sit on the inside of the window gives an extra seal for the glass. Apply a bead of the glazing to the inside of the frame (Image 1) on all four sides. The excess will be cleaned away once the glass is installed.

With the glazing applied, carefully set the glass back into the sash (Image 2) and press into the back-bedded window sash. Make sure that the glass is seated securely all around the perimeter.

Tip: Use the blade of a putty knife, rather than the tips of your fingers, to help carefully lower the glass into the frame.
Tip: Use the blade of a putty knife, rather than the tips of your fingers, to help carefully lower the glass into the frame.

Step 6: Add Glazing Compound and Clean the Sash

Using boiled linseed oil, lightly brush the inside of the glass channel on the vertical surface only and allow it to penetrate. Linseed oil conditions the wood, making it more receptive to creating a bond for the glazing compound.

Place a bead of latex based window glazing compound around the inside of the glass channel.

Using glazing push points or glaziers points, set the glass into the wood, spacing them about 8 to 10 inches apart around the whole perimeter. Roll out thin strips of oil-based glazing compound and press them into the glass channel around the perimeter of the glass. Carefully strike off the additional glazing compound around the perimeter using a putty knife or glazers knife at an angle.

Clean the sash and prepare it for reinstallation.

clean sash and prepare for reinstallation

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