Drywall mud comes in variety. It is also called joint compound, and is a white substance used together with joint tape to seal drywall joints in construction. There are two basic categories when referring to mud and it is important to know them for they are a part of drywall installation. Professional installers are familiar with these and the right type to use for a given application. The drying type of mud is vinyl based and hardens as it dries through evaporation.
This type of compound is found in a powdered form and is packaged in a paper bag lined with plastic. This helps rid of moisture and preserve the chemical’s freshness. It is essential to keep it dry. When it comes in contact with water, a chemical reaction begins and may cause it to harden. If it does, even in a small portion, you will not be able to reuse it. Hot mud sets through chemical reaction. Producers usually mix varying amounts of hardening substance into it to set up slower or faster, as required in the application. They also sell it based on hardening time. You can find it in 20, 45, 90 or higher hardening rate.
Even if the mud hardens, drywall contractors say that it does not automatically mean that it is dry. You can notice a dark gray hue turning white over time. If it turns completely white, it is already dry. Even if it is still wet, it can be recoated since it is already hard. It is called hot mud by drywall companies because of the heat emitted when mud reacts with hardening agent.
Pre-Mixed Drywall Compound
The other major category of mud is called pre-mixed, and is a traditional mud used for building projects. As the name implies, it is pre-mixed and ready to use. It is found in buckets or boxes. It is usually thinned with water before use, with the amount depending on the application. Thinner mud is used for bedding in tape. If automatic taping tool is used, smooth flow is allowed. Pre-mix compound comes in three major varieties. These include all purpose, topping and lightweight all-purpose. Most compounds are compatible with each other, but an experienced drywall installer does not recommend mixing together these compounds. The instructions specified by the manufacturer are still followed. The all-purpose joint mud can be used for all applications.