Drywall compound, also known as joint compound, is an essential material for finishing drywall seams and corners in home construction and renovation projects. With several types available, from lightweight all-purpose compounds to high-strength formulations, choosing the right drywall compound for your needs is important to achieve a smooth, durable finish. This comprehensive guide will examine the most common types of drywall compounds, their key differences, and how to select the ideal product for your drywall finishing project.
An Overview of Drywall Compound Types
Drywall compound, commonly called mud, is a pasty material used to finish drywall panels. Available in various formulations, drywall compound works by covering the seams between panels and creating a smooth, continuous surface ready for priming and painting. The main types of drywall compound include:
- All-purpose compound – Designed for most drywall finishing jobs. All-purpose compounds provide a balance of workability and strength. They can be used for embedding joint tape and finish coats.
- Lightweight compound – Contains air pockets and filler to reduce weight. Best suited for skim coats and final finish layers. Easier sanding than all-purpose compounds.
- Setting-type compound – Sets through a chemical reaction with water rather than air-drying. Produces a hard, rigid, crack-resistant finish. Used for embedding tape on first coat.
- High-strength compound – Formulated with resins and limestone for maximum strength. Ideal for high-traffic areas prone to damage. Difficult to sand.
- Lapidary compound – Ultra smooth formulation used as a final skim coat for a glass-like finish. Requires careful application.
Key Differences Between Drywall Compound Types
With various types of drywall compound available, it’s important to understand the key differences between products to select the right one for the job. Here are some of the main factors that set the types apart:
Working and Setting Time
- All-purpose and lightweight compounds – Air-drying formulations that can take 24 hours or longer to fully set and dry. Provide a generous working time.
- Setting-type compounds – Chemically harden through hydration. Set quickly, often within 2 hours. Offer less working time than air-drying compounds.
- High-strength compounds – Take longer to set and dry than lightweight or all-purpose, around 8-24 hours. Allow more time for sanding and finishing.
Sandability and Workability
- Lightweight compounds – Easiest type to sand once fully cured. Smooth, airy texture makes finishing easier.
- All-purpose compounds – Moderate sanding properties. Slightly denser texture than lightweight but sands easily when dry.
- Setting-type compounds – More difficult to sand after hardening. Best for thin applications rather than finish coats.
- High-strength compounds – Hardest to sand due to very dense formulation. Should not be used for final skim coats.
Crack Resistance
- Setting-type compounds – Harden into an extremely rigid finish highly resistant to cracking.
- High-strength compounds – Also formulated for crack resistance but not as durable as setting-type.
- Lightweight and all-purpose compounds – More vulnerable to cracking over time or if improperly applied.
Shrinkage
- Lightweight compounds – Prone to the most shrinkage as they cure. Require additional coats.
- All-purpose compounds – Moderate shrinkage. Typically need 2-3 coats for best results.
- Setting-type and high-strength compounds – Specifically designed to minimize shrinkage for a durable finish.
Choosing the Best Drywall Compound by Project
When selecting a drywall compound, it’s important to consider your specific project requirements. The most suitable type can vary based on the application area, number of coats needed, desired finish level, and other factors.
Embedding Joint Tape
For the initial layer that embeds the joint tape over panel seams, setting-type compound is the best choice in most cases. Setting-type compounds:
- Harden fast to create a rigid underlayer for finishing.
- Resist cracking better than air-drying compounds.
- Allow for thin application as needed for embedding tape.
However, some pros may opt for lightweight or all-purpose compound for the first coat over tape as it allows more time to work and position the tape.
Finish Coats on Seams and Corners
The top layers that create a smooth, continuous surface are best completed with lightweight or all-purpose compound:
- Lightweight compounds provide the easiest sanding between coats.
- All-purpose compounds also sand easily when fully cured.
- Both avoid the hardness and difficult sanding of setting-type compounds.
2-3 finish coats are typically needed for best seamlessness on seams and corners.
High-Traffic Areas
For drywall surfaces in high-traffic zones prone to bumps and dings, such as hallways or playrooms, a high-strength compound is the ideal choice for durability:
- Formulated to create an extra rigid, damage-resistant finish.
- The very dense finish deters dents, gouges, and punctures.
- Provides long-lasting integrity despite constant use and abuse.
However, high-strength compounds require careful, thorough sanding between coats.
Final Skim Coat
A perfectly smooth, blemish-free surface is achievable with a skim coat using lightweight compound:
- The airy composition sands down easily for a flawless face.
- Allows for a thin, even application free of brush marks.
- Minimizes the visible texture of the drywall underneath.
For ultra-fine results, a lapidary compound can be used but requires an expert hand.
Water-Resistant Areas
In damp or wet rooms like bathrooms and laundry rooms, water-resistant additives should be combined with the compound:
- Setting-type compounds offer natural water resistance.
- All-purpose or lightweight compounds can be mixed with water-resistant polymer additive.
Allow proper drying time in wet areas before continuing with finishes.
DIY vs. Professional Jobs
Pre-mixed, all-purpose compounds are the most DIY-friendly choice, offering:
- The broadest working time for beginners.
- The least fussy mixing and application.
- Easy sanding between coats.
For professional drywall finishers, setting-type and high-strength compounds allow greater control and speed for quality results.
Key Tips for Applying Drywall Compound
To ensure an optimal finish with your drywall compound, proper application technique is crucial. Here are some key best practices to follow:
- Carefully follow the manufacturer’s mixing instructions for any powders with water. Failure to add the right proportions can ruin the batch.
- Test consistency and make any adjustments to the compound’s thickness before starting application. It should easily spread but not be soupy.
- Load just enough compound on your drywall knife or trowel for each stroke pass. Overloading leads to mess and unevenness.
- Apply force in a consistent, even manner when spreading compound rather than scraping harshly. Let the tool do the work.
- Feather out edges of compound passes so each blends seamlessly into the next for invisible transitions between coats.
- Allow thorough drying between coats according to manufacturer guidelines before sanding or applying more compound. Rushing leads to imperfections.
- Wear a P100 respirator mask when sanding to avoid breathing dust. Also contain dust in the work area if possible.
- Prime painted surfaces immediately after the final sanding to “lock down” any residual dust before it causes bubbly imperfections under the paint.
Frequently Asked Questions About Drywall Compound
What is the difference between drywall mud and spackle?
Drywall mud, or compound, is used for taping, coating, and smoothing large areas and seams between sheets of drywall. Spackle is meant for smaller repairs like filling holes and cracks. It dries harder and can’t be built up in layers like compound.
How long does it take drywall compound to dry?
Drying times vary by product but are typically 8-24 hours between coats. Cool, moist conditions extend drying times. Warm, dry air accelerates drying. Force drying with fans is not recommended.
Is drywall compound waterproof?
Joint compound is not inherently waterproof. Water-resistant polymer additives can be mixed in, or waterproof drywall primers and paints are recommended for bathrooms, laundry rooms, and other damp areas. Setting-type compounds offer some natural water resistance.
Can I use all-purpose compound instead of topping compound?
Yes, all-purpose compounds can serve as both a base and top coat finish. However, lightweight topping compounds provide superior feathering and sanding qualities for an ultra-smooth final coat.
How many coats of drywall compound are needed?
Most drywall finishing projects require 2-3 coats over all seams and corners. The goal is to feather out each coat until the transitions are seamless and invisible under paint or texture.
Can I use drywall compound over plaster?
Joint compound doesn’t bond well to plaster. It’s better to remove any loose plaster, repair the lath where needed, and skim coat with a plaster finishing product designed for plaster walls.
How do I get rid of air bubbles when mixing drywall compound?
Let the mixed compound sit for 2-3 minutes so air bubbles can rise to the top, then remix before using. Avoid overmixing, which whips more air into the compound. Stir gently until homogenous.
Why is my drywall corner cracking?
Drywall corner cracks are often due to either inadequate compound thickness over the corner bead, or failure to feather out the compound far enough from the corner edge. Apply wider, thinner coats.
Can I use drywall compound to patch wood?
No, drywall compound should only be used on drywall surfaces. For small wood repairs, use wood filler products that are designed to bond with wood while allowing for normal expansion and contraction.
Conclusion
Choosing the ideal drywall compound for each application is the first step to achieving perfectly smooth, professional finishing results. Whether you need high crack resistance, maximum bonding strength, or super sandability, there is a specialized compound formulated just for your needs. Following best practices for mixing, application, drying, and sanding your mud will also ensure your finished drywall has a pristine, seamless look ready for priming and painting. With the right compound and some practice, you can expect results worthy of the pros.
Choosing the Right Drywall Compound for the Job
When it comes to achieving a smooth, seamless finish for drywall projects, having the right compound for the job is essential. With the wide variety of drywall compound options on the market, how do you determine what type of compound to use? Here is an overview of the most common types of drywall compounds and recommendations for choosing the optimal product for your particular drywall finishing needs:
All-Purpose Drywall Compound
As its name implies, all-purpose compound is designed to perform well for a variety of drywall finishing tasks. This type of compound:
- Provides a balance of workability, ease of sanding, and strength for everyday drywall projects.
- Is suitable for everything from embedding joint tape to skim coats and texture.
- Comes in both powder and convenient pre-mixed formulas. Pre-mixed all-purpose mud offers the simplest mixing – just open and apply.
- Sets up via air-drying within 24 hours under normal conditions.
With its versatility and ease of use, all-purpose compound is a smart choice for DIYers tackling their first drywall project. It can also handle professional jobs requiring multiple finish coats.
Lightweight Drywall Compound
Lightweight compound contains air pockets and fillers that substantially reduce its density compared to other types of products. The benefits of lightweight compound include:
- Weighs up to 50% less than conventional drywall mud, making it easier to carry and apply.
- Its airy texture also makes it the easiest type of compound to sand once fully cured.
- Provides excellent feathering and blending of finish coats.
- Ideal for skim coats and final finishes where easy sanding is essential.
Lightweight compound’s less cumbersome application and sanding ease make it a favorite for overhead work and finishing coats.
Setting-Type Drywall Compound
Setting-type compounds undergo a chemical reaction that causes them to harden once mixed with water, rather than drying by evaporation like other types. Setting-type compounds offer:
- Very strong rigid finishes highly resistant to cracking.
- The ability to set and gain strength quickly, often within 2 hours. This allows for same-day recoating.
- A suitable base for finish coatings in high-traffic areas.
The fast hardening of setting-type compounds also makes them ideal for embedding tape on the first coat over drywall seams. However, their quick set time limits workability.
High-Strength Drywall Compound
Where durability is a priority, a high-strength compound is formulated to create an extra-tough finish:
- The addition of resins and binders produces a highly rigid, damage-resistant finish coat.
- Ideal for high-traffic locations prone to bumps, scrapes, and gouges from people or objects.
- Provides superior resistance to cracks over time.
- Takes longer to dry and cure than other types of compounds.
However, high-strength compounds are quite difficult to sand and are not recommended for final skim coats.
Specialty Drywall Compounds
Beyond the basic types above, there are also specialty drywall compounds designed for particular applications:
- Lapidary compound – An ultra-smooth formulation for glass-like final finishes.
- Acoustical compound – Helps dampen sound transmission in interior walls.
- Fire-rated compound – Formulated for fire-resistant drywall applications.
- Non-shrinking compound – Minimizes pullback as it dries.
Using the right specialty compound tailored to the specific project can optimize results.
Key Considerations When Choosing a Drywall Compound
With an overview of the primary types of drywall mud and their specific benefits, here are some of the key factors to consider when selecting a product:
- Application – Match the compound’s properties to your particular use – taping vs. finishing vs. skim coat, etc.
- Working time – Air-dry compounds allow more time to apply vs. fast-setting types.
- Sandability – Important for final coats. Lightweight and topping compounds offer smoothest sanding.
- Durability needs – High-strength compound adds extra reinforcement for high-wear areas.
- DIY vs. pro – Pre-mixed all-purpose products are the most beginner-friendly.
Choosing the optimal drywall compound for each application will help ensure your project looks professionally finished.
A Guide to Drywall Compound Types and Uses
Drywall compound, or joint compound, comes in a variety of types to suit different needs during the drywall finishing process. Selecting the right compound for each part of your project is essential for creating smooth results free of cracks and imperfections down the road. This guide covers the most common types of drywall mud and how to use them:
All-Purpose Compound
The workhorse of drywall compounds, all-purpose joint compound is a suitable choice for most finishing steps:
- Good versatility for embedding tape, filling joints, and finish coating.
- Can be used for both thin and thick applications.
- Air-dries within 24 hours under normal conditions.
- Available as powder or convenient pre-mixed formulations.
- Sands smoothly when completely dry.
All-purpose compound works well for DIYers looking for a single product to complete small drywall projects. Professionals also use it as a reliable basecoat.
Lightweight Drywall Compound
Containing air pockets and fillers, lightweight compound is designed specifically for finish coating:
- Weighs up to 50% less than conventional compounds.
- The fluffy texture also sands extremely easily.
- Ideal for overhead work where reduced weight is helpful.
- Minimizes fatigue for finishers doing extensive coating.
- Provides excellent feathering and smoothing properties.
Lightweight compound is the top choice of many pros for applying final thin, smooth coats with minimal sanding.
Setting-Type Compound
Setting-type compounds involve a chemical reaction with water that causes rapid hardening:
- Hardens fully within 2 hours after mixing.
- Creates an extremely rigid base layer highly resistant to cracking.
- The quick set time limits working time but allows for same-day recoating.
- Ideal for quickly embedding joint tape on the initial coat over seams.
The high strength and fast cure make setting-type compounds perfect for the first layer over newly taped joints.
High-Strength Compound
High-strength drywall compound contains resins and binders for maximum rigidity:
- Formulated to create a damage-resistant finish able to withstand heavy use.
- Provides unmatched resistance to dings, gouges, and punctures.
- Ideal for high-traffic areas like hallways or kids’ rooms.
- Significantly more difficult to sand than lightweight or all-purpose compounds.
- Not recommended for final finish coats or skim coats.
For drywall surfaces prone to abuse, high-strength compound adds much-needed reinforcement.
Specialty Compound Options
Beyond the basics above, there are also specialty compounds designed for specific applications:
- Acoustical – Contains sound-deadening additives.