Wood filler and wood putty serve different purposes in finishing and repair work. Using the wrong product leads to finish failures, poor adhesion, and repairs that telegraph through the final finish. Here’s how to choose correctly.
Wood Filler Composition
Wood filler is a water-based or solvent-based product designed to fill larger voids, gaps, and defects in bare wood before finishing. It contains wood particles or cellulose fibers suspended in a binder. When it dries, it hardens completely and can be sanded smooth.
Quality fillers accept stain reasonably well, though they never match the surrounding wood perfectly. The stain absorption rate differs from solid wood, making filled areas slightly lighter or darker than the surrounding material.
Wood Putty Characteristics
Wood putty is an oil-based product that stays pliable even after application. It’s designed for filling small holes and defects in finished wood—after staining and sealing. Putty doesn’t harden fully, allowing it to flex with the wood through seasonal movement.
Putty won’t accept stain since it’s applied over sealed wood. Instead, it comes pre-colored to match common wood tones and stain colors. You select the shade closest to your finished wood color.
When to Use Wood Filler
Use wood filler for:
- Gaps in joints that opened during glue-up
- Nail holes in trim before painting
- Defects in bare wood before staining
- Gouges and dents in unfinished wood
- Filling around knots that need stabilizing
Apply filler generously, letting it mound slightly above the surface. It shrinks as it dries, so overfilling prevents depressions. Sand it flush after it’s completely dry—typically 30 minutes to 2 hours depending on depth and humidity.
When to Use Wood Putty
Use wood putty for:
- Nail holes in stained and sealed trim
- Small defects discovered after finishing
- Touch-ups on furniture with existing finish
- Filling gaps in finished cabinetry
Press putty into the hole with your finger or a putty knife, then wipe away excess with a clean cloth. The pliable consistency makes it easy to work into small holes without disturbing the surrounding finish.
Staining Considerations
If you plan to stain the wood, use filler before applying any finish. Let the filler dry completely, sand it flush, then stain the entire surface. The filler will absorb stain differently than the surrounding wood, but this beats trying to match stain colors with putty later.
Some woodworkers mix sawdust from the project wood with wood glue to create a custom filler that matches better than commercial products. This works for small repairs but isn’t practical for larger voids.
Painted Surfaces
For painted projects, wood filler is the clear choice. Apply it before priming and painting. Sand it smooth, prime the surface, then apply your topcoat. The filler will disappear completely under opaque paint.
Water-based fillers work well under water-based paints and primers. For oil-based paints, either product works, though solvent-based fillers may integrate slightly better with oil-based primers.
Structural Repairs
Neither product adds structural strength. For areas requiring structural integrity, use epoxy wood filler or replace the damaged section entirely. Standard wood filler and putty are cosmetic products that hide defects but don’t restore load-bearing capacity.
Drying Time Differences
Wood filler requires drying time before you can proceed with finishing. Factor in 30 minutes minimum for thin applications up to several hours for deep fills. Putty applies to finished surfaces and needs no drying time—you can work over it immediately after wiping away excess.
This timing difference matters when you’re on a tight schedule. If you discover a nail hole after finishing, putty lets you fix it and continue immediately. Finding the same hole before finishing means applying filler, waiting for it to dry, sanding, and then proceeding with your finish schedule.
