filling holes in wood putty

8 Ways to Fill Large Holes in Wood

When you’re working with old wood, chances are you’ll need to make repairs like filling large holes from rot and poor craftsmanship. Whether you’ve got a more advanced woodworking project like repairing rotted wood on furniture or you just need to fill old screw holes, the following are eight of the most commonly used methods to fill large holes in wood.

Wood Putty

Wood putty is a compound used to repair holes in wood. It is available in both a ready-made form and as a powder that must be mixed with water. It has a color similar to that of wood, so it can be used to blend in holes when wood needs to remain visible in a room.

You can make your own wood putty from drywall compound and fine sanding dust, but most people buy an off-the-shelf wood filler putty. Wood putty is not the only option for filling holes in wood, but it is one of the most common wood fillers. For small holes like screw holes that need to be filled in a visible location, wood putty is the best way to go.

How to Use Wood Putty

  • The first step is to clean the hole of all debris. If the hole is deep, use a chisel or other tool to make the hole deeper so that the putty will fill it completely.
  • Next, mix the wood putty according to the instructions on the package. If it is in powder form, add water until it forms a thick paste.
  • Then, use a putty knife to fill the hole with the putty, using light pressure and a back-and-forth motion.
  • When the hole is filled, use the putty knife to smooth the surface of the putty. If there is any excess putty, scrape it off with the knife and discard it.
  • Let the putty dry completely, which usually takes about 24 hours.
  • Once it is dry, sand it smooth with fine-grit sandpaper or electric sander until smooth. Apply stain or finishing products as needed.

Two Part Epoxy Products

There are a few different ways to fill wood holes with epoxy. The best way to do it depends on the size and shape of the hole. Epoxy works well because it adheres to and fills the pores and fibers of wood, much like a dye or varnish would. Epoxy can be purchased at most hardware stores, usually sold in two-part resin kits. These epoxy kits are convenient because they include a hardener, which is mixed with the resin to create a durable and waterproof filler.

If the hole is small, you can use a putty knife or a ball of epoxy to fill it. For larger holes, you can try mixing sawdust or wood shavings to create a paste. This paste can then be applied to the hole and smoothed out with a putty knife. Once the epoxy dries, sand it down until it is flush with the rest of the surface. After this, you can apply paint or varnish to the surrounding area to conceal the patch.

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Epoxy can also be mixed with sawdust to create a paste. This works for holes that are large or deep holes in wood.

Epoxy requires a bit more skill to use, but it’s ideal for large holes or wood that is extremely rotted. There’s not much a craftsman and epoxy can’t fix!

Wood Glue with Toothpicks

Wood glue is a fast-drying adhesive that can be used to bond two pieces of wood together. It’s also great for filling in holes and cracks in wood, as it dries clear and is practically invisible. If the wood has a deep hole or is rather large, the glue + toothpicks route is a viable option. In order to use wood glue to fill a hole, you’re going to have to know how to apply it.

How to use Wood Glue and Toothpicks

  • Clean the hole as best you can. The first step is to clean the hole. This means removing any debris or bits of wood that may be in the way. You can use a screwdriver or something similar to scrape off the bulk of the debris, then finish cleaning it out with your fingers.
  • Apply wood glue into the hole by dripping it almost until it’s at the top of the hole. Then, start putting toothpicks inside the hole until it’s “filled”.
  • Let the glue dry. Allow the glue to dry for at least an hour or up to 24 hours.
  • Sand the glued area. Once the glue has dried, use some fine-grit sandpaper to sand the area until it’s flush with the rest of the wood.

Wax Candle

Sometimes you’re in a pinch and you need to work with what’s available. In this case, a candle can act as a substitute wood filler.

  • Start by trimming the wick of the candle to about 1/4 inch. This is for better precision. You don’t want a long wick because the flame will make the wax too hot, and it could drip all over your project.
  • Now, melt the end of the candle by sliding it between your thumb and forefinger. You don’t need much heat—just enough for the end to start looking like it’s melting.
  • Carefully drip the wax into the hole, and let it cool. You may need to do a couple of layers, but make sure to let each layer dry before dripping more wax.
  • When you’re finished, buff the surface and use a piece of sandpaper to smooth the surface. Then, apply your favorite stain, and you’re done!
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Wood Plugs + Wood Dowels

Wood plugs (ora wood dowel) are a popular and advanced way to repair large wood holes. Wood plugs are small pieces of wood that are used to fill holes in other pieces of wood. They’re available at hardware stores and typically come with a flat base so that the wood plug can be pressed flush against the surface of the wood. They’re an excellent wood filler.

  • To use a wood plug, first find the hole that you want to repair. The size of the hole will determine the size of the wood plug that you need to use. Next, use a chisel or knife to cut a square or rectangle around the hole.
  • The depth of the plug should be slightly shorter than the depth of the hole. If it is not, then use a chisel or knife to shave off the excess until the plug is at the right depth.
  • Next, use a hammer to drive the wood plug into the hole. The plug should be flush with the surface of the wood. If you are using a screw, then use a drill to make a hole in the center of the plug. The screw should be able to sit flush against the surface of the wood. For a more permanent hold, you can use wood glue before putting the plug into the hole.
  • After you are finished with your project, paint or stain over the wood plugs to hide them from view.

Sawdust/Glue

Another option is to use sawdust and wood glue. Mix the sawdust and glue together until you have a thick paste. Then, apply it to the hole and let it dry.

Baking Soda & Vinegar

Another option is to use a baking soda and vinegar mixture. Mix the baking soda and vinegar together until you have a thick paste. Then, apply it to the hole and let it dry.

Elmer’s Glue Stick

Finally, another option is to use an Elmer’s Glue Stick. Just spread and fill the glue over the hole and let it dry.

More tips for filling holes in wood

  • Sit the wood board on a flat surface. This allows you to add the wood filler to the wood hole evenly and without spilling. Flat surfaces are always best.
  • If possible, fill the hole in a climate-controlled space. Extreme temperatures can affect the drying time and quality and prevent your wood fillers from working correctly. Beware of cold temperatures especially as these can speed up drying times and cause cracking.
  • Give the material time to completely dry. Many times, large holes in wood can take a lot of wood filler material, which means a longer drying time. Don’t rush things or try to start repairs before the wood filler has completely dried. Look at the hole carefully and apply gentle pressure before moving on.
  • Rotten wood can sometimes be unrepairable. While it’s always worth a shot, sometimes a hole in wood can be so rotted out that it’s not worth fixing. Depending on your project and needs, you may consider a fresh piece of wood
  • Prepare your workspace correctly. This includes:
  • Make sure your workbench is clean
  • Gathering the right materials like painter’s tape, a drop cloth, craft sticks, glue, disposable paper plates, wood filling, sand, or whatever material you decide to use
  • Using an electric sander for sanding and smoothing out the filled area
  • Using a vacuum or broom to clean up sawdust and debris
  • For larger holes:
    • Make sure you have enough material to adequately fill the hole.
    • For very large holes or deep holes, you’ll want to use a two-part epoxy kit
  • For smaller holes:
    • Wood glue, paste, or putty can do the job just fine. Make sure to use the correct amount and take your time so it’s doesn’t make a mess
    • Use wood plugs for smaller holes in delicate objects like furniture or guitars for precision repair
    • Once you’re done repairing, you may need to add a second coat or third coat of paint to accurately match the finish and stain you desire if the wood surface doesn’t look good enough.
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No matter which method you choose, make sure to let the material dry completely before you start painting or using the wood again. Otherwise, the paint or finish may not adhere properly.

About Peter Jacobs

Peter Jacobs is the Senior Director of Marketing at CNC Masters, a leading supplier of CNC mills, milling machines, and CNC lathes. He is actively involved in manufacturing processes and regularly contributes his insights for various blogs in CNC machining, 3D printing, rapid tooling, injection molding, metal casting, and manufacturing in general. You can connect with him on his LinkedIn.

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