Painted Trim Touch-Up: Filling Nail Holes And Caulking Gaps After Trim Installation

By Bruce W. Maki, Editor

Start:

After paint-grade trim is nailed in place, the nail holes and gaps need to be filled. If the trim was primed and painted before installation (which is my preferred method), then a final coat of paint can be applied and the trim job is complete.

When pre-painted trim is used, it's often not necessary to mask off the adjacent areas, which means this last coat of paint can be applied with minimal time and effort.

There are many wood filler products available. These are two that I have used recently. On this job, I used the tube of Zar latex wood patch because it was easier to apply.

Filling Holes With Wood Putty:

Before using the tube of wood putty, I squeezed and kneaded the tube to make sure the material was thoroughly mixed.

I just placed the tube tip over the nail hole and squeezed the putty out. This seems to do a good job of filling the void.

Then I wiped off the excess putty with a small putty knife.

On the contoured portion of the scarf joints, I squeezed out some putty along the gap and wiped off the excess with my finger.

It's tempting avoid the need for sanding by wiping out the excess with a damp paper towel, but that method "scoops out" much of the putty from the hole. Then the holes will certainly need to be filled a second time.

Most of my mitered outside corners had small gaps. I used my finger to force the putty into the gaps, then I wiped off the excess with a paper towel.

When all the nail holes and outside corners were filled with putty, I allowed the putty to dry for a couple of hours before sanding down the excess material.

Caulking Gaps:

There are two types of gaps that I fill will caulk instead of wood putty: 1) Gaps between the top of the baseboard and the wall, and... 2) Gaps at coped inside corner joints.

I cut a very small opening in the tip of a new tube of siliconized acrylic latex caulk. Then I ran a small bead of caulk along the gap at the top of the baseboard.

I wiped off some excess caulk with a small putty knife. I stopped every few inches and wiped the caulk off the putty knife, otherwise the excess caulk would get all over the trim.

Then I used a wet paper towel to wipe the caulked joint, making sure I removed any excess caulk from the trim and the wall. (This wasn't as easy as it looks.)

On the inside corner joint I ran a small bead of caulk.

I scraped off the excess with the putty knife.

Then I wrapped a wet paper towel around the putty knife and wiped the corner again, being careful to get into all of the crevices in the trim profile. I found it helpful if I shifted the towel often so I was wiping with a clean area. These blue paper "shop towels" are really helpful here, because I can easily see the white caulking, thereby preventing the goo from getting all over everything.

While the caulk dried, I returned to the job of puttying the nail holes.

When the first coat of putty was dry, I sanded the spots with 100 grit sandpaper. Then I applied a second coat of putty, because the first coat shrunk and I could see small dimples at each nail hole.

Sometimes I've been able to overfill the nail holes and leave a slight mound of putty. After sanding, this putty spot will often be flush with the wood, and not need a second coat. But trying to make that slight mound of putty can be tricky and slow, so I just scrape of the excess and accept the need for a second coat.

After I sanded the second coat of putty, I applied some masking tape and painted the trim again. I applied masking tape to the floor under the entire length of the baseboard. This tape had glue on only half of the paper's width. On the walls, I only applied masking tape to the areas where I needed to touch up the paint on the top surface.

After the paint dried, I had to use a small knife to cut the paint that had bonded to the masking tape. If I didn't do this, the masking tape would rip.

The Finished Product:

My experience is: There are always minor flaws in any finish carpentry job, but few people (besides the carpenter) ever notice the flaws. My philosophy is: If the trim looks good up close, then it'll look better from farther away.

The original trim in the upstairs of this 1960's house was plain, boring "modern baseboard". I much prefer the subtle details of this 5¼ inch traditional baseboard.

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Written November 18, 2009