Finishing

Lacquering

Lacquer forms a closed film on the wood. It protects strongly, but also changes how wood feels, how it ages and how it is repaired. This page explains the types of lacquer, how lacquer is applied to veneer and intarsia, the typical faults, and how lacquer differs from hard-wax oil, the finish on every Reihax piece.

Diagram in section: on the left lacquer as a closed film on wenge and ash, on the right hard-wax oil, which soaks in and leaves only a thin layer at the surface, with the pros and cons of both finishes below — Lacquer and hard-wax oil in section, layer thicknesses greatly exaggerated: lacquer lies on the wood as a film, hard-wax oil soaks in and leaves only a thin layer on top.

What lacquer is

Lacquer is a film-forming finish. It is applied as a liquid, and once the water or solvent has evaporated and the binder has cured, a closed layer lies on the wood. Oils, by contrast, soak into the top fibres and cure there; hard-wax oil combines that with a thin layer of wax at the surface. In section the difference is small, in daily use it is large: it decides how the surface feels, how it copes with water and how it is repaired.

For veneer and intarsia, three groups are the main candidates:

Water-based lacquer: mostly based on acrylic or acrylic-polyurethane. It smells little, hardly yellows and keeps light woods such as ash light. On the first coat the water raises the grain, and it brings out the wood less, so dark woods can look somewhat flatter.
Nitrocellulose lacquer: dries very fast and is easy to touch up, because a new coat redissolves the old one. It is less resistant than polyurethane, needs good ventilation and yellows over time.
Polyurethane lacquer: very hard and resistant, as a one- or two-component lacquer. Solvent-based versions bring out the wood strongly and warm light woods. Two-component lacquer calls for exact mixing and protective equipment.

Lacquer in a spray can is usually one of these types in a small quantity. It suits small objects, but needs steady movement and several very thin passes.

How lacquer changes wood and contrast

Every finish changes the colour of the wood, lacquer no less than oil. The figure stands out more clearly and the tones become deeper. Solvent-based lacquers and oils do this strongly and give light woods a warmer, slightly yellowish tone. Water-based lacquers do it only a little; light woods stay closer to their raw colour, while dark ones look somewhat less deep.

In intarsia that is a question of contrast. A pairing of wenge and ash lives on the gap in lightness. A finish that deepens wenge and keeps ash light widens the gap; one that warms both shifts it. How this plays out with different pairings is described on the page contrast and colour temperature. You only know for certain from a sample made of the same woods.

Flow No. 2 twice: on the left raw after sanding, on the right finished with hard-wax oil — Flow No. 2 raw and with hard-wax oil. Every finish deepens the wood and changes the contrast; a water-based lacquer would probably have kept the ash lighter and deepened the wenge less. Workshop light on the left, studio light on the right.

What is different on veneer

Lacquering solid wood is more forgiving than lacquering veneer. Three points call for particular attention on veneer and intarsia:

Sanding between coats costs thickness: each coat of lacquer is sanded lightly before the next. At edges and corners the veneer is quickly cut through, and a sand-through cannot be hidden under lacquer (fixing mistakes).
Water raises the grain: water-based lacquer raises the fibres on the first coat. So the sanded surface is dampened beforehand with a damp cloth, left to dry, and the raised fibres are sanded off finely. The first coat of lacquer then stays smoother.
Open pores: coarse-pored woods such as oak, ash and wenge take lacquer into their pores. If the pores stay visible, the surface is called open-pored; if they are to disappear, more coats or a grain filler are needed. For intarsia whose joints should stay clear, open-pored is usually the calmer choice.

Applying lacquer

Diagram of the four steps of lacquering: prepare, prime, light sanding and top coat — Lacquering in four steps. Drying times and grits are given on the tin and take precedence.

Lacquer is built up in thin coats, not in one thick one. A thick coat runs on vertical faces, dries unevenly and bridges the joints of a pattern, so the boundary between two woods looks softer. A typical build-up is a primer or sealer, a light sanding and one or two top coats.

Spraying: with a spray gun or a spray can. Gives the most even surface, but needs a dust-free, well-ventilated space and even passes with a little overlap.
Brush or roller: with a fine lacquer brush or a foam roller, quickly and along the grain. Quite manageable on small surfaces; brush marks only level out if the lacquer is made for it.
Conditions: about room temperature and normal humidity. Cold lengthens the drying time, high humidity can make solvent-based lacquers turn milky.
Sanding between coats: with fine paper, around 320 to 400 grit, or an abrasive pad, only enough to make the surface matt and smooth. Then remove the dust thoroughly.

Sheen

Lacquers range from matt through satin and semi-gloss to high gloss. The sheen changes more than the impression of value: the higher the gloss, the more the surface mirrors and the more clearly it shows every scratch, every unevenness and every speck of dust. On small objects under a desk lamp, high gloss creates bright spots that cover the pattern. Matt and satin surfaces keep the light calm (matt surfaces). Reihax pieces are satin, but with hard-wax oil, not lacquer.

Typical faults when lacquering

Runs and sags: too much lacquer at once, especially on vertical faces. Sand off once cured and re-lacquer thinly.
Orange peel: a dimpled surface, mostly from spraying at the wrong distance or with lacquer that is too thick. Sand flat and apply again.
Dust nibs: grains in the film from the air or the workpiece. Remove dust thoroughly beforehand, and do not lacquer in a room where sanding has just been done.
Craters: small round flaws where the lacquer pulls apart, mostly caused by traces of silicone or grease on the surface.
Blushing: solvent-based lacquers turning milky in damp or cold air. Work warmer and drier.
Sanded-through edges: from sanding between coats at edges and corners. Sand with hardly any pressure and only on the flat.

Lacquer or hard-wax oil

Lacquer is not a better or worse choice than oil, but a different one. It protects better against water, stains and abrasion and forms a smooth, closed surface. In return, a layer lies between hand and wood, and a scratch in the film is usually repaired not at the spot but across the whole face. Oil and hard-wax oil leave the wood tangible and can be retreated locally, but protect less against standing water.

Rather lacquer: when moisture and stains are likely, when light woods should stay as light as possible (with water-based lacquer), or when a smooth, closed surface is wanted.
Rather hard-wax oil: when the wood should stay tangible, when the surface should be easy to refresh later, and when a calm, satin sheen is wanted.

Reihax does not lacquer. All pieces, the pen holders as well as the wall art, are finished with hard-wax oil in a satin sheen, in two thin coats with a light sanding with a fine abrasive pad in between. How hard-wax oil is applied and looked after is described under hard-wax oil and caring for handmade wooden objects.

Checklist before lacquering

Type of lacquer chosen for the effect wanted: water-based keeps things light, solvent-based brings out the wood
Sample of the same woods lacquered and checked in the light the piece will live in
Surface fully sanded, dusted, free of grease and silicone
With water-based lacquer: surface dampened beforehand and raised fibres sanded off
Thin coats, sanding between them with hardly any pressure, edges spared
Dust-free, ventilated room at room temperature
Drying times and grits as the manufacturer states

Frequently asked questions

Can intarsia be lacquered?

Yes. Lacquer is a common finish for veneer and intarsia and protects especially well against water and stains. What matters are thin coats, a careful light sanding between them so the thin veneer is not cut through at the edges, and a sample with the same combination of woods, because lacquer changes light and dark woods differently.

Water-based or solvent-based lacquer for veneer?

Water-based lacquer smells little, hardly yellows and keeps light woods light, but raises the grain on the first coat and brings out the wood less. Solvent-based lacquers such as nitrocellulose or polyurethane dry differently, bring out the figure more and warm light woods, but need good ventilation. Which one suits depends on how the wood should look in the end.

Lacquer or oil for intarsia?

Lacquer protects better against water and stains and forms a smooth, closed surface. Oil and hard-wax oil soak in, leave the wood tangible and can be touched up locally. Reihax uses hard-wax oil in a satin sheen on every piece; lacquer is a good choice where protection from moisture matters more than feel and easy repair.

How many coats of lacquer does veneer need?

Usually a primer and one or two top coats, each applied thinly with a light sanding in between. More coats build more film, which visually bridges the joints and puts the wood further from the eye. The manufacturer’s drying times and grits take precedence.