How to Use a Drywall Trowel: Techniques for Smooth Finishing

Ridges and tool marks show under gloss finishes because of heavy-handed passes. Smooth finishing needs the right tool per joint and thin, controlled coats. A flat trowel handles taping and smoothing; a curved trowel works butt joints and seams where you want less horizontal pressure.

What Each Trowel Does

Flat trowels are general-purpose, built for smoothing joint compound, plaster, EIFS, and stucco. The flat face presses compound into a seam and feathers it flush. Curved trowels are companions for finishing, not replacements, used as an intermediate layer on butt joints and seams; the curve reduces horizontal squeeze where a flat face bites too hard. Own one and it should be flat.

How to Use a Drywall Trowel

Load thin, spread evenly, feather every edge into the board.

1. Load compound on the trailing edge, not the leading edge — a shallow bead you can push, not a heavy scoop.
2. Draw at a low angle with steady pressure, letting the blade flex rather than mounding compound.
3. Feather edges to nothing before bare board. USG’s guidance calls for feathered edges of at least 2 inches on the finish coat.
4. Let dry, then smooth tool marks and protrusions with a finishing knife before the next pass.
5. Apply a thin finish coat and feather again. Multiple thin coats beat one heavy one; the third coat should be thin by design.

You’ll know it worked when the joint feels flat and light rakes across without a shadow line.

USG states Level 5 is the highest quality finish, minimizing joint photographing and fastener show-through, required where gloss, semigloss, or enamel finishes are specified or under critical lighting. Level 4 suits flat paints, light textures, or wall coverings. Both demand a surface free of tool marks and ridges, so trowel work decides which level you deliver. If you’re deciding between a 14-inch flex blade and a 16-inch curved one, this comparison of tested drywall trowels breaks it down by joint type.

Mistakes That Show Under Paint

Most callbacks trace to three habits: coats too thick, edges left unfethered, ridges never smoothed between passes. Thick compound works against USG’s thin-coat guidance — a heavy coat skins over, shrinks, and leaves a crowned seam that catches light. Tool marks conflict with USG’s smooth, uniform surface requirement and fail Level 4 or 5 specs fastest. Wrong trowel type slows you down rather than ruining the wall: curved trowels suit butt joints; flat trowels are the general-purpose option for taping and smoothing. Curved guidance assumes pairing with a flat trowel — a curved trowel alone won’t carry the job.

For the tools themselves, USG’s finishing guidance and the construction handbook remain the standard reference for coat sequence and feathering, and manufacturer pages list current blade specs.