Drywall, commonly known as plasterboard, is used to fit boards to walls instead of using plaster.
A taping knife is simply a tool that is used on drywall to smooth, spread, lay tape, and fill gaps.
It’s characterized by a wide, thin blade and a paintbrush-type handle that makes it easy to hold onto.
The knife gets its name from the fact that its main use is laying tape when erecting drywall.
Taping knives are versatile tools that come in a wide variety of sizes. Usually, they range between three and 14 inches.
Using smaller taping knives measuring three to six inches, you can enjoy greater control of the tool and get into the smaller nooks and crannies of the drywall.
Using a smaller knife also means you’re able to use a bit more force to ensure you are effectively filling the seams and screw holes.
They are commonly used for filling gaps, laying tape, decorative work, and applying joint compounds to seams.
With a larger taping knife, you don’t need as much force, and you can cover more area at one time.
They are best used for feathering the edges, otherwise known as blending, as well as spreading.
It is a good idea to have both a large and small taping knife on hand because they will be needed for various drywall processes.
The Taping Knife Blade
The blade of the taping knife can be made out of various materials depending on the brand or type you buy.
They are either made from blue steel, stainless steel, or carbon steel.
Each one of these options is good, but they all come with unique benefits that some prefer over others.
Stainless steel is a steel alloy that has a chromium content of a minimum of 10.5 percent.
This blend of metal makes an alloy that won’t corrode, stain or rust in water the way that typical steel can.
Because it is nearly entirely rustproof, you won’t have to worry about leaving behind any rust marks on the wall.
This will also save you plenty of time when you are cleaning your tools.
Blue Steel gets its name from the process of “bluing.” During bluing, steel gains protection from rust.
It is named Blue Steel because of the bluish-black appearance of the finish when all is said and done.
This kind of steel is not nearly as stiff and rigid as stainless steel, meaning it is ideal for feathering jobs.
It is still recommended that you use a water-displacing tool to stop the blade from rusting over and to help keep it clean.
Carbon steel is a different kind of steel alloy that has a maximum carbon amount of two percent.
Carbon steel is commonly used as a catch-all name for any steel that isn’t stainless. This type of steel is more flexible than its stainless counterpart but, if not kept clean, tends to rust.
No matter which metal you end up going with for the blade, it is a good idea to break in the tools before you use them to ensure they operate with the flexibility you want.
The Taping Knife Handle
When it comes to the handle, taping knives are available in quite a few different materials.
The most common among them are wood, rubber, and plastic.
Wooden handles are the most traditional choice and are considered the most aesthetically pleasing as well.
This kind of handle excels in both durability and comfort, and while they might be a bit more expensive than the other options, you can count on them for longer.
If you plan on toting these around in a tool belt, it’s good to keep in mind that they can be a bit heavier than rubber or plastic options.
This kind of handle is the most inexpensive of the options and still works well.
They aren’t always as comfortable to hold as rubber or wooden handle, so that’s important to consider.
Rubber Knife Handles
Made specifically to offer total comfort while using it, rubber handles bring together durability and ergonomics in one.
They will give you a better grip on the handle, which is especially important for jobs like feathering, which requires plenty of attention to the details.
An offset handle is raised, giving your fingers plenty of room to move.
This gap between the blade and the handle also lessens the risk of marking up the wall.
It also lets you get the blade flat against the wall, which is important if you want a smooth finish.
Soft-touch handles let you enjoy a better grip and are commonly made of soft rubber.
A long handle taping knife is good for reaching high-up areas like ceilings without the need for a step ladder.
Of course, this means carrying extra weight and dealing with a clunky tool that doesn’t fit well in a tool belt. They come in various materials and lengths.
What is a Taping Knife Used For?
Taping knives, as mentioned, are used for a wide variety of jobs. Below are a few of their common applications.
Spreading joint compound or wood filler
A taping knife can be used to plug up any gaps in the wall.
Not only for filling the joint compound, but you can also use it for filling the wood fillers on large wood surfaces.
Laying tape on drywall joints
Using tape and drywall joint compounds, you can fill in gaps and stop them from coming apart or cracking open.
The knives are used to apply this mud compound to the joint or seam before a layer of tape is added on top of it. Then, another layer of mud is applied to ensure everything is sealed correctly.
When you are installing plasterboard, or if you have a crack in a plastered wall to repair, you can use a taping knife to do the job.
A joint compound, often simply called mud, is a white material that is like plaster and is used to seal and fill any gaps between the various layers of plasterboard.
Drywall joints are the gaps or seams between the pieces of plasterboard. Such gaps are filled with the aforementioned mud compound.
How Should You Use a Taping Knife?
Using a taping knife requires some patience and getting used to it, but it isn’t very hard.
Holding a Taping Knife
A standard taping knife is held with your thumb beneath the handle with two fingers on top of the blade. This will give the necessary pressure you need.
An offset handle will allow you to instead hold it with a full grip while still enjoying the ability to put the blade flat on the wall.
Using a Taping Knife While Drywalling
Step 1: Apply mud to the blade
Using a small taping knife, apply two inches of mud to the edge of the blade.
Step 2: Begin in the corner
Work outward from the corners of a room and force the mud into the seams and divots there.
Step 3: Smooth the seams
After filling the seams, keep the knife at a 25-degree angle against the work surface and use it to smooth the mud in a single motion if you can manage it.
Step 4: Remove excess
Use the knife to scrape off any extra mud and return it to the top.
Step 5: Lay the tape
Use the jointing tape by centering it on a seam and pressing it into the mud.
Step 6: Cut the tape
After the tape has reached the end of a seam, tear off any excess.
Step 7: Smooth the tape
Begin in the middle of the tape, and with the knife at a 25-degree angle, smooth it from one end to the other.
Step 8: Crease the tape in joints
Cut the tape as needed and fold it lengthwise to tape any inside corners of a joint.
Finally, smooth and apply a second coat.
Caring and Maintenance
You can extend the useable life of a taping knife by cleaning it frequently.
This kind of knife is best cleaned with water alone and a bit of scrubbing.
If you’re worried about rust, you can rub the blades down with WD40 to keep them free of it.
If you let the mud dry on the blade, it will be difficult to clean later, so clean it as soon as you can.
Why are some drywall knives curved?
Drywall knives mainly come in three types – straight, curved, and taping.
Curved knives (also called utility knives or putty knives) have a curved blade that usually curves inward at the tip.
They are designed in such a way because it allows the user to make tight cuts in corners and around other obstacles such as outlets and doorknobs. Curved knives are also better at getting into small spaces.
Can a dull taping knife be sharpened?
Taping knives can absolutely be sharpened! I recommend that you sharpen your taping knife regularly – about once a week or so – to keep the blade nice and sharp.
There are a few different ways that you can sharpen your taping knife. You can use a sharpening stone, a honing rod, a file, or even a power drill with a sharpening attachment.
Once you’ve chosen your sharpening method, simply run the blade along the sharpening surface a few times until it is nice and sharp.
Be careful not to over-sharpen the blade, however, as this can damage the knife.
If you’re unsure how to sharpen a taping knife, there are plenty of tutorial videos online that can show you the ropes.
Also, you should consider replacing your drywall knife when the blade has become excessively dull or damaged.
There is no point in sharpening the damaged knife, which is not comfortable to use anymore.
What to look for when choosing a drywall knife?
When choosing a drywall knife, you must consider the cuts you’ll make.
A curved knife is a fantastic choice for cutting corners if you’ll be doing a lot of corner-cutting.
A straight knife is a superior choice for making long, straight cuts. A taping knife is the most versatile option if you plan to do both cuts.
When choosing a drywall knife, also consider the following:
- The size of the blade
- The length of the blade
- The handle (e.g., plastic, wood, metal)
- The grip (e.g., curved, textured)
- The weight of the knife
The bottom line
A putty knife usually is a lighter tool with thinner blades than a taping knife.
Because of the less flexible blade of a putty knife, it can be better used for filling screw holes and working in tight spots as opposed to a taping knife.
A scraper, on the other hand, is similar to a taping knife, so much so that they are commonly used interchangeably.
Even so, scrapers have a beveled or sharpened edge that makes it simpler to remove unwanted paint or putty, which taping knives can’t do.
So, choose the one that is ideal for your job and can help you get the results you desire for.
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Jack Luis is a semi-retired painter who loved painting his clients’ ideas on their walls.
He had worked as a painter for over a decade serving customers in areas such as Charleston, Mount Pleasant, Beaufort, and Georgetown, SC (South Carolina). Today in his free time, he likes to read and write about the newer techniques implemented in his profession. You may read more about him here or get in touch with him here.