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How to Avoid & Get Rid of Bubbles in Adhesives

Air bubbles in adhesives can weaken bonds and compromise the durability of your project. These pesky air pockets can compromise the strength and durability of a bond, resulting in poor performance and potential failure in critical applications. Whether you’re working with industrial adhesives or small-scale DIY projects, ensuring a bubble-free bond is key to achieving optimal results.

In this blog, we’ll explore why bubbles form in adhesives, how to get rid of them, and the best practices for ensuring a strong, lasting adhesive bond.

Why Air Bubbles Form in Adhesives

Air bubbles are a common challenge during adhesive application and can arise due to various factors, including mixing methods and application techniques.

• Mixing: Manually combining resin and hardener for bulk adhesives often introduces air into the mixture. This is especially problematic when adhesives are poured or transferred during the process.
• Dispensing: Applying adhesive incorrectly, such as shaking cartridges before use or dispensing in a way that traps air, can lead to bubbles forming within the bond.
• Differences in Packaging: Adhesives sold in cartridges (with static mixing nozzles) significantly reduce the risk of bubbles, while bulk adhesives, which require manual handling, are more prone to air entrapment.

Understanding these causes is the first step in addressing the issue.

Mixing Adhesives: Common Pitfalls

Cartridge-Based Adhesives

Cartridge adhesives are a go-to choice for ease of use and consistency. Equipped with static mixing nozzles, these systems automatically mix the correct ratio of resin to hardener while minimizing air bubbles. They offer:

• Precise dispensing with fewer manual errors.
• Significantly reduced risk of air entrapment during application.

Bulk Adhesives

When working with bulk adhesives, the risk of bubbles increases:

• Manual Mixing: The act of stirring resin and hardener together introduces air into the mixture.
• Pouring: Transferring or pouring adhesives after mixing often traps air within the adhesive.

Techniques to Eliminate Bubbles in Adhesives

If bubbles have already formed, don’t worry—there are effective ways to remove them:

1. Vibrating Table

A vibrating table agitates the adhesive, encouraging bubbles to rise to the surface, where they can be popped.

• How It Works: Place the mixed adhesive on the vibrating table. As the table shakes, bubbles rise naturally.
• When to Use: Best for larger batches of adhesive or applications where manual removal is impractical.

2. Hot Air Tools

Heat can cause air bubbles to expand and burst.

• Tools: A hair dryer or hot air gun can do the job effectively.
• How to Use: Apply heat gently to the adhesive surface for one to two seconds until bubbles expand and pop.
• Precaution: Avoid overheating the adhesive to prevent altering its curing properties.

3. Vacuum Chambers

For thorough removal of bubbles, vacuum chambers are highly effective.

• How It Works: The vacuum removes air from the adhesive mixture, forcing bubbles to expand and escape.
• Best Practices:
  • Use a large enough container to allow for bubble expansion without overflow.
  • Gradually reduce the vacuum pressure to prevent sudden adhesive spillage.

Preventing Air Entrapment During Adhesive Application

Even if your adhesive is bubble-free at the start, improper application can reintroduce air into the joint. Follow these steps to minimize air entrapment:

1. Avoid Shaking Adhesive Containers

Shaking disperses air bubbles into the adhesive, making them difficult to remove. Always handle adhesive containers gently.

2. Dispensation Strategies

• Zigzag Pattern: Apply adhesive in a zigzag motion across the substrate instead of creating a ring or outline. This method evenly distributes adhesive without trapping air.
• Center Bead Application: Apply a bead of adhesive at the center of the substrate and press outward to spread the adhesive toward the edges.

3. Clamping Techniques

Proper clamping is essential to avoid post-application bubbles:

• Ensure adequate time for the adhesive to reach handling strength before unclamping.
• Avoid unclamping prematurely, as this can cause relaxation in the joint and lead to air ingress.

Adhesive Manufacturing and Transport Considerations

Manufacturers ensure that adhesives are bubble-free at the production stage through vacuum mixing and degassing. However, transportation can introduce air into the product:

• Freight Vibration: Movement during transit can lead to the formation of bubbles.
• Post-Transport Handling: Before application, use a vibration table or vacuum chamber to eliminate any bubbles that may have formed during shipping.

Best Practices for Bubble-Free Adhesive Bonding

To ensure optimal results, follow these best practices:

1. Use Cartridge Adhesives When Possible: They are easier to use and minimize air entrapment.
2. Employ Vibrating Tables or Vacuum Chambers: These tools are essential for removing air from bulk adhesives.
3. Apply Adhesive Strategically: Use zigzag patterns or center bead applications to reduce air entrapment.
4. Handle with Care: Avoid shaking adhesive containers or applying unnecessary pressure during application.
5. Adhere to Curing Guidelines: Allow adhesives to fully cure and reach handling strength before releasing clamping pressure.

Conclusion

By understanding the causes and implementing the outlined techniques—such as using vibrating tables, hot air tools, and vacuum chambers—you can achieve strong, reliable adhesive bonds. Proper application methods, combined with a careful approach to adhesive handling, ensure long-lasting results that meet your expectations.

A bubble-free bond isn’t just a possibility—it’s a standard you can achieve with the right tools, techniques, and practices.