Handy Wood Craft

 

 

Achieving a High Quality Wood Finish - part 02

Favorite furniture woods are maple and cherry, both have a nice figure, are easy to machine, and cherry has a wonderful fruity smell when cut. Maple has a couple of advantages over cherry. Nicely figured maple is easier to find and less expensive, and since it has a similar grain pattern, properly stained maple is almost indistinguishable from cherry, but, both cherry and maple have a reputation for being difficult to finish.

 

Cherry and maple do not stain evenly. Their highly prized figure results from end grain that rises to the face of the board in irregular patterns. Most finishers attempt to stain cherry and maple using pigment stains, but because end grain soaks up pigment much more rapidly than does face grain, the result is blotchy, uneven color. Cherry has an additional finishing downside: even if you successfully achieve a uniform deep red color with stain, it will not last. Cherry darkens with age, stained cherry may eventually become too dark. The only way to achieve a true deep red cherry color without any chance of the wood becoming too dark is to let it darken naturally. This may take several years, however, and most of us are unwilling to wait that long. Your alternatives, then, are to stain it anyway and take your chances or use maple stained to look like cherry. Whichever you choose, the following finishing steps should give good results.

 

Preparing the wood

 Preparation techniques could fill a book, so I’ll just hit the high points here. Sand all surfaces evenly, working your way up through sanding grits from course to fine, skipping every other grit: 60, 100, 150, 220. The idea is to use 60 grit to eliminate tool marks and flatten large surfaces, then use each successive grit to eliminate the scratches left by the previous grit. On flat surfaces back your sandpaper with a sanding block. Use a shop light and sight along the wood. When you have an even sheen with no scratches left from the previous grit you can move on to the next grit. When sanding by hand, do not use a lot of pressure. Just the weight of your hand and even strokes should do the job

 

If you decide to use a power sander, I highly recommend a random-orbit sander because, unlike a belt or vibrating sander, it does not leave a noticeable scratch pattern. Again, you do not need to apply pressure. The weight of the tool is sufficient.

 

Using dye stains

 

To get around the problem of uneven pigment stain absorption, use dye stains instead. The difference is important. Pigment stains are composed of tiny opaque particles of color suspended in liquid. When applied to the wood, these particles lodge in pores and scratches, and the open ends of end grain where they are sucked up by capillary action, resulting in a blotchy appearance. Pigment stains also highlight sanding mistakes and obscure, rather than enhance the figure of the wood.

 

Dye stains, on the other hand, are completely dissolved in liquid and therefore can soak directly into the cells of the wood, coloring the entire surface evenly. Dye stains even out flaws in the color of the wood, hide sanding mistakes, and, because they are translucent, bring out the figure.

 

There are three kinds of dye stains: water-based, alcohol-based, and oil-based. I use water-based dye stains for a three reasons. First, they are easier to find and come in a wider variety of colors. Second, they are less prone to fading in bright light. Third, the solvent is cheap: distilled water is about a dollar per gallon, and tap water can be used in a pinch. The only downside to water-based dye stains is that they require an extra sanding step because they tend to raise the grain of the wood. Other than that, all three types perform identically, so I’ll confine my discussion to water-based dye stains.

 

Raising the grain

 

Water soaks into the wood and swells the fibers, resulting in fine "whiskers" on an otherwise perfectly sanded surface. It is necessary, therefore, to deliberately raise the grain of the wood and sand off the whiskers before applying water-based dyes. To do this, simply take a clean sponge or rag soaked in warm water, wet the surface of the wood, and let it dry. Once the wood dries lightly sand off the raised whiskers with 320 grit sandpaper, sand only enough to remove the whiskers; too much sanding will cut through to the un-raised grain underneath, defeating the purpose. Remember to use a sanding block on flat surfaces. Repeat this process a couple of times. By the third wetting you should feel no more raised grain.

 

Choosing the Color

 

Dye stains come in a variety of colors, usually as powder in one-ounce bottles, and are easy to blend. It is hard to tell from the color of the powder or a chart what the dye will look like on your project, so while you’re at the store moisten a finger and stick it in the powder and wipe it on a sample of your wood or slip of paper. Find a couple of colors that look close, then a couple more at the extremes of the range you are interested in. For example, I like a deep orange-red mahogany color so I’ll choose "dark mahogany" or "cherry mahogany" for starters, and then get something really yellow in case the others are too red and something really red in case they are too yellow.

 

Mixing the Dye

There are two ways to mix dyes. You can mix them together in a single batch to get the color you want, or you can blend them by successive applications on your work. Since you’re going to apply several coats of dye anyway, and since it’s difficult to duplicate a mixture, I recommend blending them on the work.

 

To experiment, collect and finish-sand some left over wood from your project. If you are refinishing an existing piece, experiment on a concealed area. Mix about 1/8 tsp of dye per cup of water and try different combinations. The dye will look dull when it dries so wet the surface with some mineral spirits to get an idea of the finished result. When you are satisfied with the color, record the sequence of dyes you used.

 

Applying the Dye

Thoroughly mix about 1/2 oz (1/2 bottle) of dye per quart of hot (not boiling) distilled water, wet the wood with the dye then wipe off the excess with a dry rag to help ensure even coverage and minimize excessive penetration. Even though dyes will not blotch like pigments, leaving the wood wet will result in uneven color. Let the surface dry. If any additional grain-raising occurs, remove the whiskers by sanding very lightly with 400 grit paper.

 

Some finishers skip the grain-raising step discussed earlier and let the dye raise the grain. The danger here is that sanding raised grain at this point may cut through the color. Though this can be remedied with successive applications of dye, the result will be an uneven appearance. Therefore, I recommend keeping the two steps separate.

 

written by Paul Koch