How to Repair Surface Damage on Unfinished Furniture
No matter how carefully you shop, unfinished furniture is likely to have a few problems. The joints may be loose; moving parts may stick. There are usually a few knots in the wood, and these will bleed through the finish if they aren't sealed. There are almost always rough edges or saw marks. Before you prepare the wood for finishing, take the time to deal with these problems. Your results will more than justify the effort.
Loose Joinery and Poor Assembly
The first step in working with unfinished furniture is making sure it's solid. Examine the joints to locate any weak points; drawers are especially likely to need refastening. If the staples or other fasteners are solid, renailing may not be needed, but if they're off-center or don't look very secure, reinforce them by driving finishing nails next to them. Drill pilot holes for the nails to keep the wood from splintering. If the staples are loose, pull them out with pliers, and renail the joint. Fill the staple holes with wood filler.
Loose legs, rungs, arms, or spindles should be reglued. Test all parts of the piece to make sure they're secure, and reglue or refasten any loose part.
If the piece has drawers, they should work smoothly. Check the drawer guides, inside the frame, and the runners on the bottom edges of the drawer. They should be square and securely fastened, with no protruding nail heads. Refasten the guides or runners, if necessary, and countersink protruding nail heads with a nail set.
Knots and Sap Pockets
Examine the wood carefully for spots where sap has flowed or resin beaded on the surface. Scrape off hardened resin, and clean knots and sap pockets with turpentine on a soft cloth. If large knots are loose, remove them entirely; then apply carpenters' glue around the edges and replace the knots, flush with the surface.
If small knots are loose -- pin knots -- remove them completely and fill the holes with wood plastic or water putty. Seal all knots and sap pockets with a coat of 1-pound-cut white shellac; if the shellac is completely absorbed, apply two or more coats, as needed, to seal the knots completely.
To correct surface roughness, sand the edge smooth. If there are low spots or gaps in an edge, fill them with wood filler or water putty and then sand the filler smooth. Square edges should be very slightly rounded before finishing; smooth and round them with fine-grit sandpaper on a sanding block. Do not plane edges; planing could splinter the wood.
Saw Notches and Splinters
Dull saw blades leave notches and splinters, and you're likely to find these problems anywhere the wood has been cut or joined. If the notches are very shallow, you may be able to sand them out. In most cases, you'll have to fill them with wood plastic, and then sand the filler smooth.
Special Finishing Steps
Unfinished furniture requires the same preparation and finishing as stripped furniture, but it also requires a few preliminary steps.
First, sand the wood very thoroughly. Unfinished pieces are usually rougher than stripped pieces; start sanding with medium-grit sandpaper and then work up to fine-grit. Make sure all edges, knot faces, joints, and door and drawer interiors are completely smooth.
Raw wood must be carefully sealed. Unsealed wood absorbs moisture, and this can cause serious problems. If the piece of furniture has drawers, seal them inside and out with a coat of thinned white shellac or sanding sealer, to prevent warping and splitting. Seal all hidden parts -- drawer guides, side and bottom panels, and any other exposed wood. Seal the entire piece of furniture, and then lightly sand it again to remove any tooth from the surface. Any further finishing you would like can be done at this time.
Unfinished wooden furniture can turn out to be a bargain if you know what to look for and which minor surface damages are easy to repair.
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