Shellac
Shellac is a resin carried in alcohol. Zinsser's Bulls Eye Shellac lists denatured alcohol and ethanol as its solvents, dries to the touch in 30 minutes and can be recoated in under an hour at 70°F and 50% humidity; drips clean up with denatured alcohol or ammonia and water. It comes in clear and amber. Zinsser says it will not yellow or darken with age and that its dried film is non-toxic — the maker's claims for its own product. Between coats, Zinsser sands with 220 grit or finer.
| Product | Type | Touch | Recoat | Cleanup |
|---|---|---|---|---|
| Zinsser Bulls Eye Shellac | Shellac, clear or amber | 30 min | Under 1 h | Denatured alcohol; ammonia and water |
| Zinsser SealCoat | 100% dewaxed shellac sealer | Sand after 45 min | 1 h for a second coat | Denatured alcohol; ammonia and water |
| Minwax Clear Brushing Lacquer | Brushing lacquer | 30 min | 2 h; 24 h before normal use | Lacquer thinner |
Zinsser's times are at 70°F and 50% RH. Minwax gives no conditions for its lacquer's times.
Dewaxed shellac as a sealer
Shellac's most common job in a modern finishing schedule is as a sealer. Zinsser makes the distinction between its two products explicit: SealCoat is 100% dewaxed and, Zinsser says, compatible with all clear finishes — oil- and water-based polyurethane, lacquer and shellac — while it does not recommend Bulls Eye Shellac as a sealer under polyurethane and points to SealCoat instead. SealCoat can also be thinned as a pre-stain conditioner on softwoods such as pine, and Aqua Coat specifies a dewaxed-shellac seal coat over water-based stain before its grain filler. Zinsser labels SealCoat for interior use only.
Brushing lacquer
Lacquer coats fuse: Minwax says each coat of its Clear Brushing Lacquer melts into the one before, so no sanding is needed between coats for adhesion, and that coats dry to the touch in 30 minutes, which leaves little time for dust to settle. It calls for at least three coats with a natural-bristle brush — a foam brush, it warns, will dissolve — and 24 hours before normal use. Minwax says the lacquer stays clear rather than ambering like polyurethane, and that it is not for floors.
Caution— Lacquer and polyurethane
Minwax answers 'no and no' to putting lacquer over polyurethane or polyurethane over lacquer: they are not compatible and adhesion can fail. Shellac's place between incompatible finishes depends on which shellac — Zinsser's dewaxed SealCoat, not its Bulls Eye, under polyurethane. When in doubt, test on scrap.
Safety— Flammable solvents
NFPA lists lacquers among flammable liquids whose vapours can ignite. Keep lacquer — and shellac, as its label directs — away from flames and sparks, ventilate while they dry, and follow each label.
Like any film, these finishes eventually chip or wear, the Forest Products Laboratory notes. For a slower-drying, tougher-film alternative see polyurethane; for the choice between films and oils, wood finish types.
Using shellac or lacquer
- Dewaxed shellac if anything will go over it, per Zinsser
- No lacquer over polyurethane, or polyurethane over lacquer, per Minwax
- The right brush: natural bristle for Minwax's lacquer, never foam
- Cleanup solvent at hand: alcohol for shellac, lacquer thinner for lacquer
- Ventilation and no ignition sources
- A test on scrap over any stain or old finish
Sources
Compatibility statements are each maker's for its named products and are not extended to other brands. Times are at the conditions each maker gives. French polishing, a traditional padding technique for shellac, is beyond the makers' instructions reviewed and is not covered.
- 1.
Technical Data BEY-06, Zinsser Bulls Eye Shellac. Rust-Oleum (Zinsser), 2021.
Used for: Bulls Eye Shellac as a shellac-based sealer and finish in clear and amber, with denatured alcohol and ethanol solvents: 30 minutes to touch and recoat in under 1 hour at 70°F and 50% RH; 220 grit or finer between coats; not recommended as a sealer under polyurethane, for which Zinsser points to SealCoat; maker's statements that it will not yellow or darken and that its dried film is non-toxic; cleanup with denatured alcohol or ammonia and water.
- 2.
Technical Data BEY-07, Bulls-Eye SealCoat Universal Sanding Sealer. Rust-Oleum (Zinsser).
Used for: SealCoat as a 100% dewaxed shellac sanding sealer, compatible with all clear finishes including oil- and water-based polyurethane, lacquer and shellac; interior only; 45 minutes before sanding with #120 or finer; a second coat after 1 hour; usable as a pre-stain conditioner on softwoods.
- 3.
Minwax Product Guide. Minwax.
Used for: Clear Brushing Lacquer: dry to touch in 30 minutes, recoat after 2 hours, 24 hours before normal use, at least 3 coats, lacquer-thinner cleanup, no sanding needed between coats because each melts into the last, a natural-bristle brush, foam brushes dissolving, not for floors or spray equipment, staying clear where polyurethanes can amber, and lacquer and polyurethane not compatible either way; oil- and water-based polyurethanes over each other once fully cured.
- 4.
Technical Data Sheet, Clear Wood Grain Filler (130-099). Aqua Coat.
Used for: A seal coat of dewaxed shellac over water-based stain before grain filler.
- 5.
Mark Knaebe. Finishes for Wood Bowls, Butcher Blocks, Other Items Used for Food, and Children's Toys (FinishLine). USDA Forest Service, Forest Products Laboratory, 2013.
Used for: Shellac and lacquer as film-forming finishes that eventually chip, peel or crack.
- 6.
Safety with Oily Rags (safety tip sheet). National Fire Protection Association, 2019.
Used for: Lacquers listed among flammable liquids whose vapours can ignite.
About this guide
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