The outsole bonding process, commonly referred to as “outsole cementing,” is a crucial step in shoemaking that involves attaching the shoe’s upper to its outsole using adhesives. This method is widely used due to its efficiency and the strong bond it creates, making it ideal for various types of footwear.

Step-by-Step Guide to Outsole Cementing:

1. Gather Necessary Tools and Materials:

   • Adhesive Cement: A high-quality contact cement like Barge is recommended.
   • Cement Thinner: Ensure compatibility with your chosen adhesive.
   • Application Brushes: For precise adhesive application.
   • Sandpaper or Rotary Buffing Tool: To roughen surfaces for better adhesion.
   • Shoe Last: A mold that shapes the shoe during construction.
   • Clamps: To hold components securely during bonding.
   • Non-Staining Tape: To protect areas from adhesive spills.
     
     

2. Prepare the Outsole:

   • Cleaning: Wash the outsole with hot, soapy water to remove mold lubricants and impurities from the manufacturing process.
   • Drying: Ensure the outsole is thoroughly dried after washing.
     
     

3. Prepare the Upper:

   • Lasting: Insert the shoe last into the upper, ensuring a snug fit. Tighten any laces to remove slack and use a hammer to seat the heel and toe areas firmly onto the last.
     
     

4. Test Fit:

   • Align the prepared upper with the outsole to verify proper fit. The outsole should fit tightly without gaps or overhangs.
     
     

5. Surface Preparation:

   • Roughening: Use sandpaper or a rotary buffing tool to scuff the bonding surfaces of both the outsole and the bottom of the lasted upper. This enhances adhesive grip.
     
     

6. Adhesive Application:

   • First Coat: Apply a thin, even layer of cement to both prepared surfaces. Allow it to dry as per the adhesive manufacturer’s instructions.
   • Second Coat: Apply a second layer of adhesive to both surfaces and let it become tacky, typically for about 10-15 minutes.
     
     

7. Bonding:

   • Alignment: Carefully align the upper and outsole, ensuring all edges match correctly.
   • Pressing: Press the components together firmly, starting from the toe and working towards the heel to avoid air pockets.
     
     

8. Securing the Bond:

   • Hammering: Use a flat-faced hammer to tap along the bonded areas, reinforcing the adhesive bond.
   • Clamping: Apply clamps to maintain pressure on the bonded shoe, allowing the adhesive to cure effectively.
     
     

9. Final Touches:

   • Cleaning: Remove any excess adhesive from the shoe’s exterior using appropriate solvents or tools.
   • Inspection: Check the shoe for any misalignments or defects, making necessary adjustments.

By meticulously following these steps, you can achieve a durable and professional bond between the upper and outsole, ensuring the longevity and quality of the footwear.