Stucco and Concrete bonding agents

Summary

Kirk Giordano, a seasoned plastering expert, discusses the proper use of Weld Crete, a bonding agent for stucco applications. Drawing on over 30 years of experience, Kirk explains why he sometimes dilutes Weld Crete, despite the manufacturer's instructions, particularly for color coat applications on painted surfaces. He shares valuable tips, emphasizes the importance of proper preparation, and warns against common mistakes like over-applying bonding agents or mixing them with stucco. Kirk advises homeowners to follow the can's directions and seek professional help for stucco color coats to avoid potential failures.

Takeaways

• 👷 Weld Crete is a popular bonding agent used in the plastering industry, especially for adhering color coats.
• 🚫 Despite the label warning against dilution, Weld Crete can be diluted for specific applications, such as color coats over sealed surfaces.
• 🏗️ Weld Crete is typically used full strength for applications like concrete to concrete bonding.
• 🎨 A color coat is much thinner (1/8 inch) compared to stucco, which may be half an inch or more.
• 💧 Diluting Weld Crete can be done in a ratio of two parts Weld Crete to one part water, but it should be done with caution and experience.
• 📅 Weld Crete can be applied and then stucco or cement can be applied within an hour, and it remains effective for up to 10 days.
• 🏠 For older houses with multiple layers of paint, applying Weld Crete full strength can lead to spider checking in the color coat.
• 🚿 A clean surface is essential for the bonding agent to work effectively; dust, dirt, or mossy surfaces will prevent adhesion.
• 💡 Kirk recommends against adding bonding agents directly into the stucco mix for a color coat application, as it can cause the finish to fail.
• 🌟 Weld Crete is praised for its strength and reliability, being one of the strongest liquid bonding agents used by experienced plasterers.
• ⚠️ It's advised to follow the instructions on the can and consult with a licensed plastering contractor for color coat applications.

Q & A

What is Weld Crete primarily used for?

Weld Crete is primarily used as a bonding agent for adhering color coats of stucco to sealed or painted surfaces, as well as for bonding concrete to concrete.

Why does Kirk dilute Weld Crete when applying color coats?

Kirk dilutes Weld Crete when applying color coats because using it full strength on well-painted surfaces can lead to spider cracking. Diluting helps the stucco color coat to adhere properly without over-sealing the surface.

What is the recommended thickness for a stucco color coat?

The recommended thickness for a stucco color coat is 1/8 of an inch.

Why does the label on Weld Crete say 'do not dilute'?

The label on Weld Crete says 'do not dilute' because it is engineered for bonding concrete to concrete, where full strength is necessary to create a strong bond over sealed or painted surfaces.

What can happen if Weld Crete is applied too thickly or full strength for a color coat?

If Weld Crete is applied too thickly or full strength for a color coat, it can lead to spider cracking because the wall loses its ability to absorb moisture properly, causing the stucco to dry unevenly from the outside in.

What are some other bonding agents Kirk mentions besides Weld Crete?

Kirk mentions Sika products and Quikrete as other bonding agents that can be used for stucco work.

Why should bonding agents not be mixed into the stucco material?

Bonding agents should not be mixed into the stucco material because they will be diluted to the point of ineffectiveness, leading to poor adhesion and causing the stucco to peel off in sheets within a few months.

What should be done before applying a bonding agent to ensure good adhesion?

Before applying a bonding agent, the surface must be clean, free from dust, dirt, or moss, as bonding agents will not adhere properly to a dirty surface.

How does Kirk recommend applying Weld Crete for color coats?

Kirk recommends applying Weld Crete lightly and diluting it with water (e.g., two parts Weld Crete to one part water) when using it for color coats. It should be applied using a brush, roller, or airless sprayer, depending on the project.

What is the potential consequence of not using the proper dilution of Weld Crete for a painted surface?

If the proper dilution of Weld Crete is not used on a painted surface, the stucco color coat may spider crack due to inadequate absorption of moisture by the underlying surface.