Even expensive, high-quality shoes can develop problems after long use. If the sole of your shoe has begun to separate, it makes more sense to repair the shoe than to replace it. The best way to repair damaged shoe soles is with a strong adhesive. Some adhesives are designed specifically for shoes. Others are multipurpose adhesives that work on many different surfaces. Some types of glue, on the other hand, typically aren't effective for repairing shoe soles.
Remove any stitching at the toe of the shoe with a craft blade. Pull back the sole as far as it will go.
Lay down newspaper to protect your work surface.
Clean both surfaces of the shoe sole with rubbing alcohol and a white cloth. A clean, old sock that has been cut open works well for this.
Sand both surfaces of the shoe sole with medium sandpaper.
Follow the instructions for the adhesive you plan to use. Pay careful attention to any precautions recommended by the manufacturer. Some adhesives give off powerful fumes, so work in a well-ventilated area if you're using a strong chemical adhesive.
Spread the adhesive on both surfaces of the shoe sole with a palette knife or other flat tool. Work the adhesive into the crevices of the sole. Use a citrus-based cleaner to remove any adhesive that gets in the wrong place.
Place the sole back on the shoe, and put the shoe on a piece of newspaper.
Cover the shoe with a plastic bag and place a heavy object, such as a large book, on top of it. Ensure that the object you place on the shoe has enough weight to press the shoe and sole together firmly. Add more weight if necessary.
Allow the glue to dry for 48 hours.
Check to make sure the adhesive you're planning to buy is appropriate for shoe repair. Use a citrus cleaner to clean the adhesive off your tools.
Do not eat, drink or smoke when handling dangerous chemicals. Do not breathe the vapours of chemical adhesives. Avoid prolonged contact between strong chemical adhesives and skin, and wash hands thoroughly after use.