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Putting a silky-smooth finish on woodwork.

The silky-smooth feeling of well-sanded wood provides a quiet satisfaction for any woodworker. How do you achieve that state of silkiness? By the several steps shown and described here--a sampling from Basic Woodworking Illustrated (Lane Publishing co., Menlo Park, Calif. 94025, 1986; $9.95).

This primer on sanding is just one of many topics covered. The new 160-page book also discusses basic woodworking tools and building techniques, and offers a collection of projects from wine racks to larger pieces of furniture.

Smoothing the surface: uses for

sandpaper, steel wool, scrapers

Surprisingly, sandpaper is not even made with sand. The material and type you use depend on the results you want.

Flint paper, beige in color, is the least expensive but also the least durable and effective material.

Garnet paper, reddish to golden brown, provides excellent results for handsanding, especially in the final stages.

Aluminum oxide, light gray to grayish brown, is a synthetic material of great toughness; choose it for rough to medium hand-sanding and for a power sander's belt or pad.

silicon carbide, blue-gray to charcoal, is often called "wet-or-dry" because its waterproof backing allows you to use it wet, thus eliminating the tendency of its tiny grains to clog. Try it as a final "polish" on wood or to cut excess gloss between finish coats.

Sandpaper type is usually labeled on the sheet's backing, along with grit number, backing weight, and designation of open or closed coat.

Grit number run from a low of 12 up to 600, but 50 (very coarse) to 220 (very fine) is the common range. Wet-or-dry paper is generally available up to 600 grit. The weight of the backing material is rated from A (thinnest) to E. As a rule, weight decreases as grit becomes finer. Closed-coat sandpaper has more particles to cut faster but clogs in soft materials; open coat works better for rough sanding. To provide a flat surface for your sandpaper, use a sanding block. You can buy one, or make your own by wrapping sandpaper around a wood block faced with a 1/2-inch-thick pad of felt or sponge rubber.

Steel wool. Sold in the form of pads in many grades, steel wool is popular among wood finishers as a mild abrasive. Grades 2/0 and 3/0 are finely textured and often used for final surface polishing before finish application. The very fine texture of grade 4/0 is perfect for smoothing between finish coats.

Scrapers. Hand scrapers appear to be simple steel cutouts, but look closer--the hooked edges produce fine shavings when pushed or pulled in line with wood grain. A cabinet scraper has two handles, making scraping less tiring and more even.

To smooth or to scrape, there's the rub

Think of scraping as planing on a very fine level. This helps explain the difference between sanding and scraping: magnified, sanded surfaces appear soft and fuzzy from the abrasives; a scraped surface looks harder and clearer. (For a similar effect, some woodworkers use a very sharp block plane.) Scrapers are particularly effective on hardwoods.

If you decide to sand, you'll need to divide the work into three or perhaps four steps. (You should at least rough-sand before assembling the parts, while you can still reach all the surfaces easily.)

To smooth wood, you can choose hand-sanding, a belt sander (for rough stages only), or a finishing sander. To remove any minor dents and scratches, lumber stamps, or scribed lines, first rough-sand as required--either by hand or with the belt sander--using 50- to 80-grit paper or a 100-(2/0) or 120-grit (3/0) belt.

Once the material is smooth and uniform in color, switch to 120-grit paper on your finishing sander or sanding block. Then sand once more with 180- to 220-grit paper. Some materials and finishes may require a fourth pass by hand with even finer paper or 3/0 or 4/0 steel wool.

On end grain, move straight across in one direction only, to avoid rounding the edges and clogging the wood pores.

Rough-sanding with a belt sander

Only a belt sander can provide the needed clout for quickly leveling or cleaning up a beat-up surface. Use the finest grit that will do the job--a 100-grit belt is usually all you need.

To fit a belt to your sander, release the lever that slackens the front roller, install the new belt with the arrow on the backing pointing in the direction of rotation, then tighten the lever. Hold the sander up and turn it on. Center the belt on the roller with the tracking control knob. When using a belt sander, remember two basic rules: clamp small materials down, and always keep the sander moving when it's in contact with the work. Belt sanders can remove a lot of material quickly.

Move the sander forward and back in line with the grain. At the end of each pass, lift it up and repeat, overlapping the previous pass by half. Don't apply pressure--the weight of the sander alone is enough.

Using a finishing sander

For intermediate and finish sanding, a finishing sander is a great timesaver. Finishing sanders take from a quarter to half a standard sandpaper sheet. To load your sander, slide one end of the paper under the clamp on one side, stretch the sheet tightly, and clamp the other end. Both straight-line and orbital sanders work best with the grain.

Sanders by hand

Traditional hand-sanding still produces fine results and, depending on the contour of the wood, may be your only alternative. To provide a flat surface for the sandpaper, use a sanding block. To cut the sandpaper to size, first fold it, then bend and tear it over a bench edge or cut it with a utility knife. Keep the sanding block flat and always sand with the wood grain.

On end grain, move straight across in one direction only, to avoid rounding the edges and clogging the wood pores.

Sanding curves is tough--you have no flat surface for the sanding block or power sander's belt or pad. But hand-sanding tricks include folding up an older, brokendown sandpaper sheet to follow the curves, wrapping the paper around a dowel or contoured block, and using a thin strip "shoeline-style."

For a curve with a large radius, try replacing the felt pad on the bottom of your finishing sander with a rubber one. A drum sander accessory for your electric drill will help you follow wavy or irregular shapes.

Finish sanding

To spot-sand patching materials, small gouges, or scratches, return briefly to a coarser grit and sand them out. Remember: sand only with the grain, and sand end grain in one direction only. Use a hand scraper, an emery board, or the crisp, folded edge of a new sheet of sandpaper to reach into corners and crevices. As you progress with finer grits of paper, check your work again with a low-angle light. You're ready for the finest grit when you've removed all the scratches made by the previous grit. Finish by vacuuming the entire piece or wiping it with a tack rag (a resin-impregnated cloth) to pick up fine dust particles.

When wood is exposed to moisture, the surface fibers begin to swell, making the wood look and feel fuzzy. Some woodworkers wet the wood down before adding any finish so they can sand down these fibers, as shown above.

Raising the grain is necessary if you're using a water-base stain or finish. If you aren't, you won't need to raise grain unless the piece has a penetrating finish and will be placed in a moist environment.
COPYRIGHT 1986 Sunset Publishing Corp.
No portion of this article can be reproduced without the express written permission from the copyright holder.
Copyright 1986 Gale, Cengage Learning. All rights reserved.

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Title Annotation:excerpt from Basic Woodworking Illustrated
Date:Mar 1, 1986
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