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Patch rotted wood.


do you have rotted wood? It's usually better to simply tear out the old board or molding and replace it than to repair it. But for windowsills and door jambs that are hard to remove and molding that would be tough to duplicate, patching with wood filler makes sense.

Fillers for repair of rotted wood generally fall into three categories. For small holes and cracks, there are fillers like DAP Latex Wood Filler or MH Ready Patch that harden as the water or solvent evaporates. Other fillers, such as Durham's Rock Hard Water Putty, harden by a chemical reaction when water is mixed in. Finally, two-part fillers like Minwax High Performance Wood Filler (polyester) and Abatron's WoodEpox (epoxy) harden after you mix the two parts.


Two-part fillers are the most durable, and the best choice for long-lasting repairs. Although polyester and epoxy are both two-part fillers, they have unique characteristics that make them quite different to work with. We'll show you the differences and give you some tips for working with these two excellent wood repair fillers.

Use epoxy for a premium repair

One common brand of epoxy wood filler is Abatron WoodEpox (; 800-445-1754). A kit containing pints of LiquidEpoxy consolidant parts A and B and WoodEpox parts A and B costs $76. Unlike polyster filler, epoxy wood filler has dough-like consistency, so it will stay put even on vertical repairs.

Prepare for an epoxy repair by removing as much rotted wood as possible. Use an old screwdriver, chisel or 5-in-1 painter's tool to gouge out the damaged wood (Photo 1). If the wood is wet, cover it loosely with a poly tent and let it dry completely before starting the repair. Drill a series of 1/4-in. holes around the rotted area if you suspect rotted wood below the surface, but don't drill all the way through. You'll fill these with consolidant to solidify the wood around the repair.

Start the repair by soaking the damaged area with epoxy consolidant (Photo 2). Mix the consolidant according to the directions. Wear rubber gloves and safety glasses when you're working with epoxy. You can mix the consolidant in a squirt bottle or a small plastic container. Use a disposable brush to work the epoxy consolidant into the wood fibers. Epoxy is difficult to remove after it hardens, so clean up drips and runs right away with paper towels. You don't have to wait for the consolidant to harden before applying the epoxy filler.



Next, mix the two-part epoxy filler on a mixing board (Photo 3). Then apply it with a putty knife or simply press it into place with your fingers (Photo 4). Roughly shape the epoxy, making sure it protrudes beyond the final profile. When the temperature is 70 degrees F, you'll have about 30 minutes before the epoxy starts to harden. Increase the working time by spreading the epoxy in a thin layer on your mixing board and keeping it cool. On a warm day, the epoxy will harden enough in three or four hours to start shaping it with a Surform plane, rasp and sandpaper (Photo 5). After rough-shaping with a plane or rasp, sand the filler with 80-grit and then 120-grit sandpaper. If you sand off too much (or didn't add enough epoxy to begin with), dust off the repair and add another layer. You can make a more spreadable filler by mixing a small batch of consolidant and a small batch of filler and then adding some of the consolidant to the filler to reach the desired consistency.




Polyester is readily available and less expensive

If you've done any auto body repair, you've probably worked with two-part polyester filler. Minwax High Performance Wood Filler is one brand formulated for wood repair, but a gallon container of Bondo or some other brand of two-part auto body polyester will also work and may be less expensive for larger fixes.

The process for repairing wood is much the same whether you're using polyester filler or epoxy. Instead of epoxy consolidant, you'll use High Performance Wood Hardener to solidify and strengthen the wood fibers (Photo 1). Polyester begins hardening faster than Abatron WoodEpox. Depending on the temperature, you'll have about 10 to 15 minutes to work before the filler starts to harden.

Also, unlike WoodEpox, polyester tends to sag when you're doing vertical repairs. One trick is to build a form and line it with plastic sheeting. Press the form against the filler and attach it with screws. Then pull it off after the filler hardens. Or you can wait until the sagging filler reaches the hardness of soap and carve it off with a putty knife or chisel or shape it with a Surform plane or rasp (Photo 2). Most medium to large repairs will require at least two layers of filler. Complete the repair by sanding and priming the filled area and then painting.



RELATED ARTICLE: Tips for working with epoxy:

* Label the caps "A" and "B" and don't mix them up.

* Start with a clean container or mixing board each time you mix a new batch.

* Save epoxy by filling most of the cavity with a scrap of wood. Glue it in with epoxy filler.

* Carve the epoxy before it becomes rock hard.

by Jeff Gorton
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Title Annotation:HOME CARE & REPAIR
Author:Gorton, Jeff
Publication:The Family Handyman
Geographic Code:1USA
Date:Apr 1, 2010
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