How to Properly Use a Taping Knife

  • 2 hours
  • Intermediate
  • 25
What You'll Need
Taping knives—various sizes
Corner tool
Drywall compound
Drop sheets
Step ladder

A taping knife is a flat metal knife used for layering and smoothing mud and plaster on walls. When doing such projects, the finish is essential. To obtain a well-finished look of your wall, you need to be familiar with different tips and techniques. The article below will touch upon such tips and techniques and aims to eventually help you in taping and mudding.

Step 1 – Take Appropriate Precautions

Taping knives have a metal blade at one end and a wooden handle at the other. We recommend the use of gloves while working with a knife for prolonged periods of time, so as to avoid possible damage to your skin. Since working with a taping knife requires a lot of elbow grease, make sure that you don’t overwork and dehydrate yourself. Always remember to keep a glass of water nearby. Since taping knives are typically used for mudding and layering, we recommend that you wear old clothes while working. In the end, using a tapping knife is more about patience than about skill. Do not apply a new coat if the previous one is not dry because the taping knife can poke through the wet undercoat very easily, thereby wasting all the hard work that you put in.

Step 2 – Choosing the Taping Knife of the Correct Size

Taping knives come in sizes ranging anywhere from 6 to 12 inches or more. The size of the taping knife plays a very important part in determining the smoothness of the mud coats. Whenever you require applying multiple coats of mud on your drywall, make sure to purchase three of more knives of different sizes. For the first coat, which usually requires copious amounts of mud, you should use a smaller knife. This will give you more control over the amount of mud that is to be applied. For the other coats, which are added to smooth the previous coat, use a knife larger than the one used previously. When selecting a size remember this general rule: for smoothing the mud or plaster, use a knife of 10 or 12 inches.

Step 3 – Using the Knife to Apply the Mud or Plaster

Hold the knife in your hand in such a manner that your index finger is placed where the knife and the handle join. This position allows optimum control while spreading the mud on the walls. Always spread the mud, in a horizontal direction except when layering mud in the corners. Ensure that the knife is clean before adding a new layer or smoothing the previous one. This ensures maximum finish and fast drying of the mud.

Step 4 – Spreading the Mud or Plaster in Corners

The technique being used in corners is a bit different than the one used on plane surfaces. You will need to tilt the blade of the knife to an angle of 45 degrees before applying the mud. This ensures that the maximum amount of mud gets into the corners to form a smooth joint between perpendicular drywalls. Always remember to apply the mud in a vertical direction while in corners as this is more convenient and makes your work very much faster.