Since I’ve been using A LOT of boxes of pre-made all-purpose joint compound, I thought I’d write down my thoughts on these two products.
Joint compound is generally used to fill in the joints between drywall to give the wall the smooth one-piece look that we’re all familiar with rather than seeing a bunch of “sections” in the wall.
But it is also used in a variety of other ways, such as for repairs, to make texture, or in my case cover already textured walls to make them flat.
Now, the main difference between lightweight joint compound and regular joint compound is, well, it’s lighter. Just carrying the boxes of the stuff around you’ll be able to appreciate the difference between the two.
However the differences go beyond just weight. Lightweight compound is “fluffier” as there is more air mixed in with it. I’ve read some comments that say this makes it harder to spread on the wall, but I have the opposite experience. Lightweight stuff for me is much easier to spread on the walls, not only because of the weight, but it’s also easier to “smear” or feather out.
Regular joint compound on the other hand, isn’t hard to smear on the wall, just a little different. It’s “smoother” so getting it to be flat is an easier job than with the lightweight stuff.
Lightweight compound does dry faster than regular joint compound, so if you’re worried about making a mistake and having it dry on you, regular joint compound is more forgiving, but it’s not like the lightweight stuff dries in 2 seconds flat or anything.
As for sanding the material after it is dried, I find that the lightweight joint compound is easier to sand than its regular counterpart, however I also find that it isn’t as sturdy. It’s easier to sand too much, and easier to dent, scratch etc.
So for my projects I tend to use both products. I will put on a base coat or two of regular joint compound, and then a finish coat of lightweight, to go over any missed spots, that way the coating is sturdy because of the regular stuff, and easier to sand down and work with when the finish coat is lightweight.
With those two working together I get a nice smooth wall (ecxept for the occasional mistake) that is pretty sturdy as well.