Red Seal Drywall Finisher and Plasterer Practice Exam

What are the main ingredients in joint compound?

1. Cement, water, and minerals

2. Gypsum, water, and additives

3. Plaster, glue, and sand

4. Clay, resin, and concrete

The correct answer is: Gypsum, water, and additives

Joint compound, also known as drywall compound, primarily consists of gypsum, water, and various additives. Gypsum serves as the main binding agent in joint compound, providing the necessary properties for adhesion and ease of application. When mixed with water, gypsum forms a paste that can be easily spread over joints and seams in drywall to create a smooth finish. The additives included in joint compound are essential for enhancing specific characteristics such as drying time, workability, and resistance to cracking. These can include materials that modify the viscosity or improve the compound's durability. The combination of these ingredients allows for a product that is user-friendly and effective in providing a seamless look to finished drywall surfaces. The other options do not accurately represent the composition of joint compound. For instance, cement is not a primary ingredient in joint compound, nor is plaster, glue, sand, clay, resin, or concrete. Understanding these components helps ensure the correct selection and application of joint compound in drywall finishing tasks.