Damaged woodwork doesn’t always need to be removed and replaced. When you repair the wood with epoxy resin, you can preserve the wood and maintain its strength.
Two-part epoxy resin is moldable by hand. After it dries, it can be sanded, carved, tooled, drilled, and machined—just like the original wood.
How Does Epoxy Resin Work?
Repairing wood with epoxy resin is a two-step process. Severely damaged wood that’s highly porous is first injected with or covered with a liquid epoxy wood consolidant. This stabilizes the wood and creates a solid base for the next step.
After the consolidant has hardened, a second type of epoxy—a clay-like, moldable putty—is pressed into the damaged area and formed into the general shape of the missing wood. After this epoxy has hardened, it is carved and sanded down to replicate the missing section.
Each of the epoxies is a two-part substance. Two ingredients, usually labeled Part A and Part B, are kept separate in different bottles. When the ingredients are mixed, they activate and become epoxy resin. The consolidant turns into a liquid, and the putty kit turns into a solid product, yet both are epoxy resins.
Repairing wood with epoxy resin is a quick repair because the epoxy hardens in about 30 minutes. It's the priming and painting that extend the project over a day or two.
Epoxy Resin Uses With Wood
Epoxy resin is often used by restoration professionals to permanently fix wood moldings, trim, and casing, as well as siding, newel posts, fascia boards, column bases, balusters, and just about any unique woodwork.
The patch must be painted, since it stands out and does not blend with the surrounding wood. Also, epoxy resin is not weather-resistant and should be coated for protection.
Know When to Repair or Replace the Wood
Replacing an item is usually a better choice than repairing it, at least in terms of structural stability. But other factors can play into the decision. While not absolutes, consider the following:
Damaged item is structural and is critical to safety
Wood is dimensional lumber that can be easily and inexpensively obtained
Wood must remain natural and show its grain (epoxy patches must be painted)
Item is historically important and must be preserved
No more than 15-percent of the wood needs to be filled with epoxy
The item is large or otherwise is difficult to move
Equipment / Tools
- Clean plastic containers
- Cordless drill and bits
- Wood rasp
- Sandpaper, varying grits
- Tack cloth
- Putty knife
- Wood chisel
- 8-in-1 tool
- Latex or nitrile gloves
- Shop vacuum
- Two-part moldable epoxy resin kit
- Two-part epoxy wood consolidant
Remove Damaged Wood
With the 8-in-1 tool, putty knife, and wood chisel, remove damaged or rotten wood. Use the 8-in-1 tool’s sharp hook to scrape out loose wood. Push the chisel forward (or use the sharp edge of the 8-in-1 tool) to chip away larger pieces of unstable wood.
Mix and Apply the Epoxy Consolidant
Mix the two parts (labeled Part A and Part B) in a clean plastic container. Mix with a wooden stirring stick. Pour directly onto the pitted wood. (It may be necessary to use a disposable paint brush to coat vertical surfaces.) Work quickly, as you have about 30 minutes of working time before the epoxy hardens. Allow the epoxy three or four hours to harden on the item.
For heavily pitted wood, fill with as much of the wood consolidant as the wood will take. It may be necessary to drill a few holes to allow for greater penetration of the epoxy resin. Be sure to coat all rot-affected surfaces to provide good adhesion for the epoxy filler.
Mix the Epoxy Filler
In a new clean plastic container, mix Part A and Part B of the epoxy resin filler. Mix thoroughly so that the two ingredients are fully integrated.
Spread the Epoxy Filler
With the putty knife, spread the epoxy filler into and over the damaged area. Over-round the damaged area so that you will have enough material to sand down in later steps. Wearing latex gloves, you can even work some of the filler by hand.
Roughly Sand the Epoxy Filler
Let the filler cure and harden for at least four hours. When the surface of the epoxy fill is hard enough to scratch with a fingernail, it will be ready for shaping. Using a rasp or rough grit #100 sandpaper, shape the hardened epoxy filler.
Sand the Filler Smooth
Clean up the debris and dust with the shop vacuum. Progress to finer grit #220 sandpaper to further remove material and to match the surrounding woodwork.
Prime and Paint the Repaired Area
Clean once more with the shop vacuum and lightly wipe down with the tack cloth. Prime the repaired area. Finish by painting with two coats of paint.