'Hot mud' is the common name for setting-type drywall joint compounds. They come in powder form and you have to mix them with water to the consistency you want. Hot mud sets up like cement instead of drying like drywall mud. The product I normally use is called Silverset 20 by Beadex. The ‘20’ means that it can be worked for about 20 minutes before it starts to set up. If you have lots of work to do you may need more time than 20 minutes. The Silverset line of joint compounds come in a variety of setting times. If you think you will need a little more time, then you can get Silverset 40 giving you 40 minutes to work before it starts to set up. These set up times are approximate so they may start setting up a little sooner or they may take a little longer. You can also make them set up sooner by using warm water.
I often use hot mud for repairs as a handyman because I need to get the repair done quickly. If you aren't in a hurry, you should probably use regular joint compound. It is easier to work with and doesn't start to get hard while you are still working with it.
