When installing drywall, joint compound, or mud, is an essential component of this process for filling seams and screw holes. But what type is best: wet, pre-mixed joint compound or dry joint compound? Before purchasing, homeowners and other do-it-yourselfers may want to consider various factors such as cost, ease of mixing and installation, and product lifespan.
What Is Joint Compound or Mud?
All-purpose joint compound, commonly called mud, is the wet material that is used for drywalll installation to adhere paper joint tape, fill joints, and to top paper and mesh joint tapes, as well as for plastic and metal corner beads. It can also be used to repair holes and cracks in drywall and plaster.
The term all-purpose refers to the fact that professional drywall installers sometimes use different types of muds for different stages of the process. For example, some professionals use a mud just for embedding paper tape, another mud for setting a base layer to cover the tape, and another mud for topping the joints.
Most homeowners and even most professionals can use the all-purpose joint compound, which works for every stage of the mudding process.
What Drywall Compound to Buy?
- For small drywall projects
- When you do not expect to store the remainder for long periods
- For large projects, to save on costs
- For storing for long periods or in freezing conditions
What Are Dry and Pre-Mixed Joint Compounds?
Drywall joint compound comes in either of two forms: dry or wet. Dry joint compound is the classic type that has been used for years and is still used by professionals. Wet joint compound is a newer product more aimed at the residential do-it-yourselfer.
Both dry and pre-mixed joint compounds contain latex additives to strength and flexibility. When mixed appropriately, both cover the same amount of drywall: about 125 to 150 pounds of compound covering about 1,000 square feet of drywall panels
Dry Joint Compound
Joint compound in the dry form is a powder that usually comes in large paper bags. The dry product must be mixed with potable water in a separate container to form workable mud. This product is usually not labeled as being dry. Simply, it will be called joint compound with the qualifiers ready-mixed or pre-mixed omitted.
- Less expensive
- Longer shelf life
- Paper bags more eco-friendly than plastic buckets
- Protected against freezing
- Will not grow mold as long as it is kept dry
- Sometimes the product is hard to obtain
- Difficult to mix, requires mixing equipment
Pre-Mixed (Wet) Joint Compound
Wet joint compound, called pre-mixed or ready-mixed, is available in plastic buckets. All water necessary has already been added to the joint compound, though it is possible to thin out the consistency with additional water.
- Perfect consistency
- No mixing
- Fast start
- Spoils quickly and develops mold
- Must not be frozen
- Dries faster in the bucket
- Heavier to carry
- More plastic waste created
Should You Buy an Electric Joint Compound Mixer?
If you do decide to go the dry joint compound route, an electric mixer may help with mixing since the product is heavy and stiff.
It is possible to mix small amounts of dry mud with an electric corded drill and a paddle mixer. But a mud mixer has a strong motor and low torque for turning heavy compounds, even small mixes of concrete. Plus, it saves your drill for what it was made for: drilling.
How much mudding with dry mix would you have to do to justify the purchase of a mud mixer? Since dry joint compound costs over four times less than pre-mixed mud, when calculating the cost to coverage area, you would need to skim-coat over 55,000 square feet to reach a breakeven point for a $170 mixer.
Note that skim coating is extremely thin and is considered to be part of a premium level 5 drywall finish, something that few homeowners will ever take on. Since most drywall finishing confines itself to narrow joint strips, you would need to finish around 400 average-sized rooms' joints to justify the cost of the machine.
Should You Buy Dry or Pre-Mixed Joint Compound?
As a homeowner, it is best to purchase pre-mixed joint compound in buckets. This type of wet mud makes your project go faster and smoother.
However, one negative about the pre-mixed compound is you are continually opening and closing the lid. This permits air and hastens the drying process inside the bucket. Worse, it can also introduce organic debris which will create mold in the mixture. Limited amounts of mold can be scooped out, allowing the rest to be used. But do this only as long as you are certain that the rest of the joint compound is 100-percent mold-free. Generally, it is safest if the moldy joint compound is discarded.
Since continually dipping your drywall knife into a pre-mixed bucket introduces foreign elements, one solution is to buy long, narrow metal or plastic mixing trays. These mixing trays allow you to portion out enough compound for this next 30 to 45 minutes of work time. Additionally, drywall knives fit into these trays; they do not fit into round buckets very well.
But as a contractor or any professional who finishes drywall with regularity, it will likely be worthwhile to purchase a mud mixer along with the dry joint compound.