Finishing Furniture with Natural Oils

Furniture is the only woodwork most people touch every day. A timber frame is admired from across the room or a field. A tabletop is under someone's hands at breakfast, and a chair arm is worn smooth by twenty years of the same grip. That changes what a finish has to do, and it is the reason oil finishes have never gone out of favor with furniture makers even as coatings have gotten harder, faster, and cheaper.

Why oil, on furniture specifically

You feel wood, not coating. A film finish puts a layer of cured plastic between the hand and the material. An oil finish cures inside the wood, so the surface you touch is the wood surface, with its texture and its temperature. On a piece someone lives with, that difference is not subtle.

Light behaves differently. Oil raises the figure in the wood by wetting the fibers permanently rather than by adding a reflective layer over them. Curl, quilt, ray fleck, and chatoyance all deepen. A gloss film adds shine on top of the wood; oil brings depth out of it.

Repairs are invisible. This is the argument that wins over time. A scratch in a film finish is a fracture in a clear layer, and it catches light as a white line that can only really be fixed by redoing the surface. A scratch in an oiled piece is a scratch in wood. Abrade the area lightly, rub in more oil, and the new finish merges with the old because there is no film edge to feather. Twenty years of small repairs leave a piece looking cared for rather than refinished.

It ages rather than fails. Film finishes have a service life and then a failure. Oil finishes have a maintenance rhythm and no particular end.

What a properly built oil finish actually resists

There is a persistent belief that an oiled tabletop will ring the first time someone sets down a cold glass. In our experience that is not what happens on a finish that has been properly built, and it is worth being precise about why, because the difference is entirely in the three things this article is teaching you to do.

A tabletop that has been well oiled, waxed, and fully cured repels water. It beads on the surface. It does not ring. We have twenty years of dining tables behind that statement.

The three conditions are not optional and they are where the reports of ringing come from:

• Well oiled means enough coats that the wood is genuinely saturated, not two thin ones on a thirsty top.
• Waxed means a buffed coat of Liquid Wax over the cured oil. The wax is what makes the surface actively water shedding rather than merely water resistant.
• Fully cured means the full month, not the two days it takes to feel dry. A surface still curing is soft and will mark, and most water rings we hear about are on tables that went into service in week one.

Skip any of the three and you get the finish people complain about. Do all three and you get one that beads.

Two things still deserve care. A hot dish set straight onto a waxed surface can soften and mark the wax, since wax melts at a far lower temperature than the oil cures at. Use a trivet. And alcohol and strong solvents will cut into oil and wax faster than into a cured film, so wipe spills rather than leaving them.

Both of those are fifteen minute repairs with an abrasive pad and more finish, and the repair disappears. That is the real difference between the two approaches. A film resists damage and then keeps it. Oil accepts the occasional mark and then releases it.

Choosing your finish

Concentrated Finishing Oil is our highest solids oil product. More finish stays in the wood per coat, so you build depth faster and with fewer applications. For furniture, where you are usually building a surface rather than just protecting one, this is generally the product to reach for. The table pictured with this article was done with Concentrated Oil, multiple coats, and buffed.

Original Finish carries more solvent, so it penetrates faster and further. It is excellent as a first coat, particularly on dense species where you want the initial application to get deep, and on larger pieces where the extra working time helps.

Many makers use both: Original Finish for the first coat to establish penetration, then Concentrated for subsequent coats to build the surface.

Liquid Wax End Sealer is the top coat. Buffed over cured oil it adds sheen, deepens the grain further, and increases surface water resistance. On furniture it is worth the extra step almost every time.

Preparation, where the result is actually decided

An oil finish is transparent and it is in the wood, not on it. That means it hides absolutely nothing and it registers everything about the surface underneath. More furniture finishes are ruined at the sanding stage than at the finishing stage.

Do not sand too fine. This is the mistake experienced woodworkers make, because their instinct from film finishing is wrong here. Sanding past roughly 220 grit burnishes the surface, closing the pores and cell openings the oil needs to enter. The finish then sits on top, cures unevenly, and looks thin. For most furniture work, stop at 180 or 220. Going to 320 or 400 will give you a worse oil finish, not a better one.

Sand thoroughly at every grit. Skipping grits leaves scratches from the coarse paper that the fine paper only polishes rather than removes. They are invisible on bare wood and glaring the moment oil goes on, because oil darkens scratches differentially. Work through the progression and check raking light before you move up.

Raise the grain first. Wipe the piece with a damp cloth, let it dry fully, and knock back the raised fibers with your final grit. Skip this and the first coat of oil will raise them for you, on a surface you can no longer sand freely.

Treat end grain deliberately. End grain drinks several times what face grain does and goes noticeably darker. On a piece where end grain is visible, at a table edge, a through tenon, a breadboard end, sand end grain one grit finer than the faces to close it slightly, or apply a thinned first coat there, and always test on an offcut.

Test blotch-prone species before you commit. Cherry, soft maple, birch, alder, and pine can blotch under any penetrating finish, showing dark cloudy patches where density varies. This is a property of the wood, not a defect in the finish. Test on an offcut from the same board, and if it blotches, you will need to decide whether you like the effect, choose different stock, or use a different finishing approach. Finding this out on the finished top is a bad afternoon.

Application

The basic method is short and it is the same as all our finishes: apply the oil, let it soak in, and wipe off whatever does not soak in.

Use the long open time. Because our finishes contain no drying agents, the oil can sit on the surface for an hour or overnight without gumming or hardening. It keeps absorbing that whole time instead of skinning over. On furniture this is a real advantage: flood the surface, walk away, come back and see where it has gone dull, feed those areas again, and only then wipe off. There is no window to race.

Wipe thoroughly. Every coat. Surplus finish left standing has nowhere to go and cures tacky, and a sticky tabletop is the most common complaint we hear. Cotton rags or a lambswool pad both work.

Wet sanding, if you want a glass-smooth surface. This is the classic technique and it is worth learning. Apply a coat of oil, then wet sand the surface with fine wet-or-dry paper while the oil is still on it. The slurry of oil and fine wood dust packs into the pores and levels the surface. Wipe off the excess thoroughly while it is still workable. Two or three rounds of this on an open-pored species produces a surface no amount of dry sanding will match.

Between coats, a light scuff with a fine abrasive pad knocks back anything that has raised and gives the next coat a key.

Building the surface you want

This is the part that makes furniture work different from finishing a timber. You are choosing a surface, not just protecting one.

• Two coats: natural matte. The wood looks oiled and honest, with no reflection to speak of.
• Three to five coats: noticeably deeper. Grain figure comes forward, the surface starts to feel dense rather than absorbent.
• Wet sanded between coats: pores filled, the surface reads smooth and close under the hand.
• Buffed: a soft low sheen that looks like age rather than coating. Hand buffing works; a power buffer works better on a large top.
• Liquid Wax top coat, buffed: the most sheen, the most depth, and the best water resistance available in this system.

Even at the top of that range the look stays natural. You cannot get a mirror gloss out of a penetrating oil, and that is not a limitation to work around. It is what the finish is for.

Tabletops and food contact

Our finishes are food safe once dry, which covers dining tables, kitchen work surfaces, serving pieces, and bowls.

Once dry is not the same as once cured. The surface will feel dry within a day or two, and the oils go on polymerizing for weeks after that. On anything that will hold food directly, give the piece its full cure before use.

For cutting boards and butcher block specifically, see our cutting board article, which covers the different demands of a surface that gets cut on and washed.

Curing

Dry to the touch within a day or two. Full cure over roughly a month, longer in cold or humid conditions and on pieces with many coats.

During the cure period the surface is soft and can mark. Keep objects off a fresh tabletop, avoid placing anything that will sit in one spot, and let it harden. The patience is the price of a finish with no driers in it, and it is the same property that gave you the long working window.

Living with the piece

Routine care. Dust and wipe as normal. For cleaning, a barely damp cloth, or an oil soap if it needs more.

When it looks dry or dull, rub in another coat of oil, or buff on a coat of Liquid Wax. There is no stripping, no sanding back, no preparation beyond cleaning it.

Water rings, heat marks, scratches, worn edges. Abrade the area lightly with a fine abrasive pad, rub in more finish, and buff out. It blends. This is worth demonstrating to a customer if you are selling the piece, because it converts the finish's apparent weakness into its actual strength, and because a client who knows how to fix a ring will not be upset by one.

High wear areas. Chair arms, drawer pulls, and the front edge of a desk will want attention before the rest of the piece. Spot maintenance is fine and expected.

Color, if you want it

Our finishes are clear and dry to a natural matte, which suits most furniture work. If you want to shift the color, our Mixol pigments can be mixed into the finish. Mix a batch, test on an offcut of the same stock, and make enough at once to complete the piece, since matching a second batch exactly is difficult.

Cleanup

Pure Citrus Solvent or other solvent to clean up brushes, spills, and hands. It also thins the finish if it has thickened in storage.

• Questions about a species, a technique, or how many coats a particular piece wants? Call us at 541-844-8748 or write info@heritagenaturalfinishes.com. We are glad to send a sample so you can test on your own offcuts first.

 

• Further reading. James Krenov's The Fine Art of Cabinetmaking is the book to read once you have the technique down and want to think about why any of it matters. Krenov built his whole practice around the surface left by a sharp plane and the conviction that furniture is meant to be touched rather than admired from a distance, which is the same argument this article makes from the other direction. He was also skeptical of finishes generally, and preferred to let good wood and good surfaces speak with as little between them and the hand as possible. That is worth sitting with. A penetrating oil is the finish that asks you to give up the least. His The Impractical Cabinetmaker is the companion, on composing and detailing.

 

• Photo and beautiful table by Peter Brown, using our Concentrated Oil, multiple coats and buffed.