How to Fill Nail Holes in Trim

Filing trim nail hole

The Spruce / Margot Cavin

Project Overview
  • Working Time: 5 mins
  • Total Time: 10 - 20 mins
  • Yield: 8 linear feet
  • Skill Level: Beginner
  • Estimated Cost: $5 to $20

Installing door or window trim, baseboards, or crown molding always results in nail holes and sometimes screw holes that need filling. These might be tiny holes created by finish nails or even tinier pinprick holes caused by power brad nailers or finish nailers.

For a clean appearance, you can quickly fill in these nail holes before painting, staining, or other trim finishes. This simple project requires only a few tools, yet the results will help your project look truly professional.


Watch Now: How to Fill Nail Holes in Trim

How to Choose a Wood Filler

All nail, brad, and screw holes in trim are filled with wood filler. There are two main types of wood fillers: water-based fillers and solvent-based fillers. Water-based wood fillers are adequate for most interior applications.

Water-Based Fillers
  • Thin and light

  • Easy to sand

  • Best when painted over

  • Best for interiors

  • Weak and crumbly

Solvent-Based Fillers
  • Thick and dense

  • Difficult to sand

  • Can be left as-is but best when painted

  • Interiors or exteriors

  • Strong and hard

Water-Based Fillers

Water-based fillers have a creamy consistency and are easy to smooth on and clean up. With interior nail holes, however, you don't need the filler to be very strong at all. Also, in many cases, the filled holes will be covered with primer and paint, both of which provide some stability for water-based fillers.

Solvent-Based Fillers

Solvent-based fillers are sticky and oily and difficult to clean up if you wait until they dry. The advantage of solvent-based fillers is that they dry rock-hard, far stronger than their crumbly water-based counterparts. Solvent-based wood fillers are best for exterior wood such as door casing, window trim, and siding.


Solvent-based filler applied thickly is difficult to sand down, so apply it sparingly.

Wood Filler Colors

For wood trim that will be painted, you can use any color of wood filler, since it will be covered with paint. If the trim is pre-finished or you will finish it with stain and/or clear sealer, carefully select a color-matched filler that blends with the natural coloring of the wood.

Fillers come in a few different colors to match common wood species. You can also purchase kits that include a filler base and colorants that you mix together to create custom colors.


While caulk is sometimes used to fill nail holes in painted trim, caulk tends to be messier and shrinks more than wood filler. Plus, caulk cannot be sanded smooth like filler can. If you use caulk as a quick alternative to real wood filler, make sure it is labeled as “paintable,” and don’t leave a smear on the wood surface, which might show up after painting. 

Filling Nail Holes vs. Leaving Them Open

Carpenters who install trim are often called finish carpenters, suggesting that their work has a finished, polished look. When installing trim yourself, you should strive for the same level of refinement. One secret to a finished look is to hide the means of attachment—in this case, the nails that hold the trim in place. And the only way to do that is to fill the nail holes.

Relying on paint alone to hide nail holes is a common mistake. Paint may seem to cover just fine when it goes on but, sure enough, the holes will be visible—in the form of tiny dimples—when the paint dries. If you’re staining or clear-sealing the wood, filler is an obvious must. In this case, it’s also important to take the time to find or mix the filler with a good color match, since the stain or sealer won’t hide it.

Tools to fill nail holes
The Spruce / Margot Cavin

What You'll Need

Equipment / Tools

  • Putty knife
  • Clean cloth
  • Latex gloves


  • Water-based wood filler
  • 180- or 220-grit sandpaper


  1. Apply the Filler With Your Finger

    For most nail holes, the space to fill is so small that it is best to use your finger. Put a small dab of filler onto your index finger. Press the filler into the hole, and give it a quick swipe. Repeat, if necessary, to fill the hole completely. It's best to overfill the hole slightly, leaving a slight, smooth ridge over the area. With solvent-based wood fillers, it's best to wear latex or nitrile gloves when spreading the filler since it is difficult to clean from your fingers.


    When applying water-based filler with your finger, keep a damp cloth nearby. Use it to occasionally wipe drying filler off of your finger to ensure consistent application. Avoid the temptation to press excess, partially dried, filler into the holes. Partially dried filler may not adhere to the wood's surface effectively.

    Apply filler with finger
    The Spruce / Margot Cavin
  2. Apply the Filler With a Putty Knife (Optional)

    Deeper or larger holes on flat surfaces may require the assistance of a putty knife. For example, if you installed the trim with screws, or if you dimpled the wood with a hammer when driving a nail, a putty knife is better than your finger for filling a larger area and for creating a flat finished surface. Scoop up a small amount of filler with the edge of the knife, press the filler into the hole, and smooth off the top to remove excess.

    Apply filler with putty knife
    The Spruce / Margot Cavin


    Close the lid on the wood filler between applications, as wood filler hardens quickly. Even a minute or two is enough for the filler to begin to develop a hard film on top. This hard section cannot be used and must be discarded.

  3. Sand Water-Based Filler With Your Finger

    One benefit of using crumbly water-based filler is that your finger can act as a type of sandpaper. After the filler has dried for about 15 minutes, sand off the crumbles and protrusions with your finger. A clean cotton glove also works well as a sanding tool. With solvent-based wood filler, you cannot sand it down with your finger once it has dried.

    Sand remaining filler with finger
    The Spruce / Margot Cavin
  4. Finish With Sandpaper

    If you do a good enough job sanding with your finger, sanding down the filler with real sandpaper is almost unnecessary. But sandpaper will always give you a better finish. Using 180- or 220-grit (extra-fine) sandpaper, gently sand the filler with a few light passes. You’re just making the filled area smooth and removing excess filler from the surrounding wood. There’s no need to remove any wood.  

    Sand remaining filler with sandpaper
    The Spruce / Margot Cavin
  5. Remove the Sanding Dust

    Clean the surface with a clean cloth or a tack cloth. Do not rub hard with a tack cloth or you risk embedding the surface with wax. Once the surface is dust-free, it's ready for primer, paint, stain, or sealer.

    Clean dust with cloth
    The Spruce / Margot Cavin