French polish and padding

Overview

French polish is not a product but a method: Shellac and a little oil applied with a pad. Alan Lacer's American Woodworker article defines it exactly so, and notes that commercial products labelled padding lacquer or friction polish are the same idea. Fine Woodworking's John Coffey describes using a pad instead of a brush to fill the grain and build a thin film. Each stroke deposits a very fine layer that dries almost at once, so it leaves no brush marks and looks deep and glossy. This entry also covers the padding technique in general (applying shellac or similar by pad); there is no separate padding entry.

When to use

• Show surfaces on furniture, boxes and turnings that are not handled constantly. Lacer recommends it for bowls, vessels and lamps not often handled or exposed to moisture, alcohol or heat.
• When you want a very thin film that fills open pores (Coffey, with pumice).
• Not for tabletops that will meet water, alcohol or hot dishes; use Oil-based polyurethane or Tabletop finish schedules recipes instead. Shellac is soft and heat-sensitive; see Shellac.

Materials and tools

• Shellac: flakes dissolved in denatured alcohol, or liquid shellac. Lacer's recipe is about a 1.5 lb cut: 1.5 oz of flakes to 1 cup alcohol, or premixed 3 lb cut thinned with an equal amount of alcohol. Wood Magazine used a 2 lb cut of garnet flakes. Shelf life: flakes very long, premixed one to three years (Lacer). Aged shellac will not harden properly. Use Dewaxed shellac if you will topcoat.
• Mineral oil as lubricant: Lacer adds 1 tbsp per 3 fl oz of 1.5 lb shellac.
• A pad (Flexner's "rubber"): wadding wrapped in a smooth, tightly woven, lint-free cloth, pulled into a ball with a flat face and twisted tight (Wood Magazine).
• Naphtha, denatured alcohol, and pumice for filling.

Steps

1. Sand through 220 (Lacer: 120, 150, 180, 220, then 320 or 400 if scratches show; maple and cherry often need the finer grits). Dust off with denatured alcohol; see Sanding schedule.
2. Make the pad and charge it with shellac, working in the pad so it is evenly damp, not dripping. Soften with alcohol first.
3. First polish (Coffey): fill the pores with shellac and pumice, which takes real effort. Grain filler (pore filler) is an alternative on open woods.
4. Pad on thin: back-and-forth strokes starting and ending off the wood. A vapour trail behind the pad shows shellac laying down; recharge when it disappears (Wilson, Wood Magazine). Vary strokes with figure eights and circles. When the pad grabs, add the smallest amount of oil to its face.
5. Wait about 30 minutes between coats on a lathe turning (Lacer), and do not rush: the next coat will dissolve the first.
6. Body up with many coats. Lacer calls five or six deep on a turning.
7. Spirit off: remove the oil, which would otherwise cloud the film. Traditional method: a pad with a little alcohol. Flexner says this is critical and hard, because alcohol easily streaks the shellac. Naphtha removes the oil in one wipe, does not harm shellac and dries within a minute; it makes the film look drier, which a wax or furniture polish corrects (Flexner). Wilson also uses naphtha to check progress, since the sheen could be oil.
8. Leave glossy, or after several days rub out with fine abrasives or automotive compound (Lacer); see Rubbing out a finish.

Common problems

• Pad sticking or dragging: add oil to the pad face; stiff cloth, soften with alcohol.
• Streaks and smears: too much alcohol or oil; rework with thin shellac.
• Cloudy gloss: oil left in the film; wipe with naphtha.
• White marks from water or alcohol later: see Repairing finish damage.

Safety and environment

Denatured alcohol and naphtha are flammable: no ignition sources and good ventilation. Rags with mineral oil and shellac should be spread flat to dry; see Oily rag safety.

Related

• Shellac, Dewaxed shellac: the finish itself.
• Spraying with HVLP: shellac can be sprayed for the same body.
• Repairing finish damage: shellac re-amalgamation and burn-in.
• Finishing schedules by species: where shellac fits.