Flat Sheen

Switch to a fine synthetic abrasive wool (0000 steel wool } equivalent) to bring the finish to a satin sheen.

dust the way a flat, horizontal top docs. A light bulling with steel wool will clean the occasional dust nib on vertical surfaces.

5. Sand with 320- to 400-grit stearated paper between coats, depending on how smooth the coat looks. Use a sanding block to level ridges and bumps. With a gloss finish, coarser paper may leave scratches that are visible through subsequent layers of poly.

6. Apply an extra coat or nvo of polyurethane on tabletops for more durability, depth and protection. Lay the last coat on a little thick to protect against accidentally rubbing through the top layer of finish. Remember, polvurediane does nor melt into itself the way shellac or lacquer do. Each layer sits on top of the previous one, so there is a danger of sanding through one lavei into die next. This will leave a visible ghost line where the top layer was sanded through. If this happens, you need to start over and reapply the hist layer of polyurethane.

7. Finish the test boards at the same time you're finishing vour tabletop. Use these sample pieces to make sure die finish is properly cured and ready to rub out. Then experiment on them to gel a feel for rubbing out.

The No.l rule for a successful rubout is to let die finish fully cure.

8. Let the finish fully cure! This is most important for a successful rubout. A finish that has not cured will not be hard enough to take an even scratch pattern from abrasives. The result will be an uneven sheen. Polyurethane should cure for two weeks to a month after the last coat is applied. II the finish balls up on the sandpaper or it won't bull out to more than a satin sheen, let it sii for another week or two.

Smooth and Flatten the Finish

It seems completely counterintuitive, but to make a finish really shine, you have to start by sanding it dull (Photo 2). Sanding removes dust nibs and brush marks and leaves the finish smooth and flat.

Caution: The finish tends to be thinner at table-top edges. Use special care in these areas to avoid sanding through (Photo 3).

9. Apply consistent, light pressure as you sand. When you're done, the surface should feel smooth and level and will still have a few small shiny spots. Don't feel that you have to completely erase every visual defect at this point—-just go for a smooth feel. Unless you have lots of bubbles to flatten, you should only need to sand five to 10 strokes in any given area with the 600-grit sandpaper. Sand dry so you can see what's happening to the finish, and change paper often. Vacuum all the sanding dust off the surface and wipe with a damp cloth. Tackcloths can be used on oil-based poly but not on water-based.

Rub to an Even, Flat Sheen

10. Begin rubbing-out with medium-grade, (00 steel wool equivalent) synthetic abrasive pads (Photo 4). This is where the finish begins to come to life, taking on an attractive, flat sheen with no visible defects.

Rub to a Satin Sheen

11. Clean the top with a damp cloth and continue buffing with fine synthetic abrasive wool (0000 steel wool equivalent) (Photo 5). Rub until the whole piece has an even, satiny sheen, and then rub a little more. There's not much danger of rubbing through the finish at this point.

Rub to a Semi-Gloss

12. To bring up the sheen even more, use soapy water or paraffin oil as a lubricant for the abrasive wool (Photo 6). Rub thoroughly; then wipe dry.

13. If that's still not enough shine for you. rub the entire surface with 4F-grade pumice. After sprinkling the pumice on the surface, rub it into a paste with water and a dampened rag (Photo 7). Wipe the slur-

Wood Finishing Rottenstone

7 Using finer and finer abrasives brings the sheen closer to a full gloss. Start with finest-grade (4F) pumice lubricated with water and a moist rag, followed by rottenstone. With these finer grits, it's OK to use a circular motion as you rub.

ry away, and then repeat the process with rotten-stone. Keep firm pressure on the rag, and sprinkle more of the powder or water as needed. Continue rubbing in any direction until your arms hurt and the finish looks satisfactory. Now your furniture has the good-looking finish it deserves.

Sources Home centers and hardware stores 3M packs of two finishing pads. 00 stee< wool equivalent, $4. 3M Sandblaster 400-gnt stearated aluminum oxide paper. $5 lor a pack of six • Woodworker's Supply. {800) 645-9292. www.woodworker.com Oilfree abrasive wool, fine <000 to 0000 equivalent), #115-271, $21 for a 4.35-liter box; medium (1 to 00 equivalent), 15-274. S21 for a 4.35-liter box 4F pumice stone. 1 lb.. «849-832. $7 Rottenstone. 1 lb. #849-839. $7. Paraffin Oil. #910-829, 1-qt.. $16

Dealing with Molded Edges

Avoid using sandpaper on molded edges, table legs and other vertical surfaces. The risk of cutting through the finish with the sandpaper is just too great. Instead, rub molded edges with synthetic abrasive pads and rub to the sheen of the top.




It's easy to see why waterborne polyurethanes have become so popular: they're as durable as solvent-based polyurethanes, they dry faster, smell less, present a lower fire risk and clean up with soap and water. If you haven't tried waterborne polvurt*thane, here are answers to some of the most commonly asked questions.

Why is waterborne poly white?

Water and m ethane, the main ingredients in waterborne poly, don't dissolve one another. That means they must be combined in an emulsion, a type of mixture in which insoluble substances can be suspended together. In this emulsion, the water and urethane molecules (which are both colorless) refract light differently making the mixture appear opaque, like milk (photo, above). After being laid on a sur face, the water evaporates, leaving the solids covering the surface in a protective, colorless film.

Which applicator works best?

For flat surfaces, many finishers prefer a paint pad—a flat plastic plate covered with thousands of tiny bristles. They're designed for applying latex paint, which is really just another waterborne finish. Soft-foam-backed versions (without handles), made for contoured surfaces, are a joy to use on flat surfaces too. Finishing pads made of velour fabric don't lose bristles and lay 011 a smooth, thin coat.

Many folks swear by foam brushes, saying thev eliminate brush marks and air bubbles and are easy to use. On the other hand, a good synthetic bristle brush can handle everything: flats, spindles, edges and inside corners. Natural bristles don't work well because they absorb water and loose their shape.

can i put waterborne poly finish over oil-based stain?

The answer is "yes," if you use a lie coal between them. As its name implies, a tie coat ties one type of finish to another with good adhesion.

A thin coat of dewaxed shellac, such as Zinsser Seal Coat will do the trick. SealCoat will adhere to the dried oil stain and the waterborne poly will adhere to SealCoat (photo at right). You can also mix your own dewaxed shellac from Hakes. Mix about two ounces of dewaxed shellac flakes into a pint of denatured alcohol and apply one thin coat to the stained wood. In about two hours you can apply the water-borne finish. Be aware that most types of pre-mixed shellac contain wax, and should not be used for this application.

Why doesn't waterborne poly look good on dark wood?

Waterborne poly makes dark woods, such as walnut or rosewood, look pale or pasty. Two things contribute to this, but both can be countered (photo at right).

First, oil finishes, shellac and lacquer make wood look wet because their molecules are small enough to get down into the wood fiber. The result is similar to what you'll see if you put oil on a brown paper bag—the paper gets darker and translucent. Molecules in waterborne polyurethanes are gigantic, compared to those in other finishes. Instead of getting into the wood fiber and "wetting" it, they can only lay 011 the surface in a colorless film that makes dark wood look lifeless. A slick way around this problem is to seal the wood first with dewaxed shellac, a compatible finish that makes the wood look wet.

Second, oil-based finishes make wood look warmer because they're slightly amber colored. Waterborne poly, on the other hand, is either colorless or slightly bluish-gray, so it doesn't add warm tones. The solution: tint the waterborne finish with amber-colored dye, such as Transtint Honey Amber dye, available from Woodcraft Supply, www.woodcraft.com. Mix the dye according to the manufacturer's directions. Then add one or two tablespoons of die liquid dye to a quart of finish. Don't be alarmed by the brown color the waterborne turns—it'll look great 011 the wood's surface.

Won't waterborne poly raise the wood's grain?

Any product that contains water will raise the wood's grain, making it feel rough after it dries The trick is to raise the grain purposely and then cut it down before you apply the finish.

To raise the grain, sponge clean water liberally over the wood after your last sanding. Then wipe it off so no puddles remain. Let the wood dry overnight and in the morning you should have raised grain (photo at right). Using 320-grit


to eliminate compatibility problems.

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Wood Working 101

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