Walls & Ceilings

What's the Difference? Joint Compound vs. Spackle

Half the battle of common home repairs is picking the correct product to use. And when two products have some overlap in their intended purpose-as spackle and joint compound do-the choice can get even trickier. Both popular putties are used in wall repair and construction, and they look almost identical to the untrained eye, but they have various formulations that affect factors like dry time, shrinkage, and the scope of a project. If you're about to tackle wall installation or repair, read on for the 411 on spackle and joint compound-and handle the job like a pro.

Spackle, made of gypsum powder and binders, has a gooey toothpaste-like consistency and is sold pre-mixed in small tubs. It's used to fill small dings and dents, like nail holes, in walls. It dries quicker with less shrinkage than joint compound-and that fast dry time (usually about 30 minutes) means you can sand and paint over the filled flaws almost right away.

Joint compound (also known as drywall mud or simply known by pros as mud) is also comprised mainly of gypsum dust that you mix yourself to a cake frosting-like consistency; you can also find it pre-mixed in a tub. During a drywall installation, contractors affix large sheets of gypsum board to the wall's framing, tape the seams between boards, and then cover the tape with joint compound. With a little bit of finish work, the joint compound helps create a smooth surface with undetectable seams. Spackle, usually sold in smaller containers, isn't suited for this purpose because its quick-drying nature gives you less working time.

Got a tub of joint compound left over from a previous renovation? Feel free to substitute it for spackle in a small wall repair. It does, however, run the risk of shrinking, calling for multiple coats, and a longer dry time-sometimes up to 24 hours.

  • Spackle varieties include a lightweight formula made with a vinyl binding agent suitable for small holes, or an all-purpose formulation made with acrylic ideal for holes up to ½- to ¾-inch in diameter. Both types are elastic, minimizing shrinkage.
  • Joint compound formulations include “lightweight,” designed for easy application to drywall seams, and “setting compound,” ideal for small patching jobs because it dries more quickly.

It's important to work quickly and keep your product covered when not in use. If you're mixing up your own joint compound with water, only make as much needed for the job at hand.

For holes in both drywall or plaster that are smaller than a half-inch, opt for a pre-mixed spackle and follow these steps:

  • Prep the area by removing loose drywall around the perimeter.
  • Apply spackle with a putty knife. Angle the knife about 45 degrees and run it in downwards motions until the hole is filled.
  • Remove excess spackle with the knife.
  • Let dry according to the manufacturer's instructions; apply another coat if necessary.
  • Smooth the surface with sandpaper when completely dry; wipe away any remaining dust.

A similar technique applies for medium-sized holes or cracks in drywall or plaster measuring several inches, but opt for joint compound and reinforcing mesh-a backing material typically made of aluminum that, once adhered to the damaged wall, gives the joint compound something to bind to. The mesh helps ensure that the repair won't dry and crumble over time. Apply the mesh to the prepped surface, covering the hole completely. Then apply the joint compound, letting it dry completely according to the manufacturer's instructions, before sanding and finishing.

If you have a very large drywall hole, you may need to patch it with a piece of drywall, some joint compound and a reinforcing scrap of lumber.