Woodworker's Journal 2011-35-Winter, страница 25
To properly fill a gouge along an edge, first build a little dam with masking tape. Keep the tape about 1/4" higher than the wood surface. Add drops of filler into the void until it is slightly proud and bulges the tape dam slightly. When the epoxy is cured, remove the tape and file or sand it flush. Tape is used to form a little dam to control your epoxy putty. ing outlets. The various brands and types of putty are more alike than different, but they're cheap enough that you can experiment with a few. Because putty must be sanded, it is applied to raw wood prior to staining. Take a small amount out of the container and use a putty knife to press it into the gouge, knothole or chip that needs filling. Leave it slightly proud of the surface, because it will shrink a bit as it dries. Make sure it is dry, then sand the putty flush to the surrounding area. Sand until the putty is exactly the shape of the original gouge. That way, you know you have gotten all the putty off the surrounding area. If you are not sure if the putty is hard enough to sand, test it by pressing your thumbnail into the center of the putty spot. If it gives or indents, let it dry further. Matching Colors Even fairly uniform wood is actually a variety of colors, due to grain and figure patterns. As a result, a fairly large putty spot often shows up as a dark or light "pond." For this reason, I find it is best to match the putty to the lightest background color of the wood. After the wood has been sealed, you can go back and add grain lines and figure colors with a fine touch-up brush and some artist's colors. The combination of the appropriate light background and some adroit touch-up can yield an almost invisible repair. Of course, it is not always easy to find exactly the right color of putty to match the background of every piece of wood. Fortunately, you can make putty either lighter or darker by mixing artist's colors into it. Use water-based artist's acrylic colors with water-based putty, and artist's oil colors with solvent-based putty. Youll find both at any craft or art store. Put a small amount of putty onto a piece of glass or a scrap of plastic laminate, add a few dollops of the colors you think you'll need, and mix them in with a putty knife a little at a time until you get just the right tint. Putty Under Stain Finding a putty that will take stain exactly the same as the wood it is on is the Holy Grail of finishing. Some putties absorb more stain than others, but some woods absorb more stain than others, too. Matching up the two is difficult at best, and sometimes impossible. If you are planning to stain your project, take a scrap of the same wood, make a gouge in it, and fill it with the putty you plan to use. Sand it when it is dry, then stain it. The putty will either be darker or lighter than the surrounding wood or, if you are living in a state of grace, it will be exactly right. Adjust the color of the putty as needed so that it is correct after the stain goes on. This may take several tries, so be patient. Epoxy and Polyester Putties Any putty will work for voids in flat surfaces, but you'll need something stronger to rebuild damage on an exposed edge or corner. For that, you can mix liquid epoxy, use a polyester body filler, such as Bondo®, or buy a special epoxy-based wood putty. Both epoxy and polyester fillers tend to be fairly runny, so you'll need to make a "dam" out of masking tape to hold them in place until they harden. Epoxy wood putty, like the SculpWood* in the photo below, starts as two soft clays. Mix the same size ball of each together with the other by kneading them in your gloved hands. Once mixed, press the soft clay into the void and shape it to match the missing profile. It will cure hard and can be filed, carved, sanded and finished. When I have to rebuild a corner, I add a tack or two to anchor the putty so that it won't break off after it sets. You can even use epoxy or polyester fill to "cast" small replacement parts, such as broken pieces of carvings. These alternative putties are more difficult to color, and are best reserved for pieces that will be stained dark or painted, unless your touch-up skills are finely honed. A moldable epoxy putty results from mixing two clay-like components together. Form the epoxy clay to the shape of the missing part, using anchor tacks to make sure the putty stays put. WINTER 2011 25 |
