Shellac - Canadian Woodworking Magazine

shellac_lead

Shellac



Shellac is the finish that poses no problems: it’s easy to apply, easy to clean up, and easy to repair. If you are looking for a smooth gloss like finish that gives an exceptionally deep lustre, then look to shellac.

Like lacquer, shellac is an evaporative film finish. It’s comprised of solids (a natural resin from an insect) and a solvent (alcohol). When the solvent dries, the finish solidifies; add solvent to the dry finish and it dissolves.
 
Shellac as a Good Finish
Compared to other finishes, shellac is nearly foolproof. It dries so fast that you’ll have little problem with dust. It doesn’t stink up the shop like other finishes, and if you’re careful with the solvent you use, it’s easy on your health - the resulting finish is non-toxic.
 

shellac_1
Premixed liquid shellac
 
Because it’s so easy to sand, shellac is often used as a sealer coat under other finishes to raise wood fibres. It is also surprisingly water resistant (more so than oil finishes), and it has excellent resistance to water vapour exchange, which makes it an excellent choice for cabinet and drawer interiors.
 
Some Caveats
Any alcohol concentration greater than about 10% will cause shellac to dissolve, which is to be expected, given that alcohol is the solvent for shellac. Leave water sopping on shellac and it will turn white, while boiling water or alkalis like lye or ammonia will damage the finish. Also keep in mind that shellac has a lower resistance to abrasion than varnish and lacquer, so you wouldn’t want to use it on a dining or coffee tabletop.
 
In a Dry or Liquid Form
Shellac is available in two forms: as flakes, which you mix with alcohol, or as premixed liquid. While flakes have an indefinite shelf life, in liquid form, shellac will last only about 6 months, although it will last up to 3 years in an unopened container. However, you’re unlikely to find a pre-mixed container stamped with a ‘mixed on’ date, so it’s a good idea to write the date on the container when you first open it. If you’re trying shellac for the first time, or if you need only enough for a small project, then buying premixed shellac is the way to go. Liberon dewaxed shellac is available as ‘Easy French Polish’ in clear and amber grades, and also as ebony, button, garnet, and special pale polishes. The Easy French Polish contains ‘copal’, a natural resin that makes the shellac easier to brush on and slightly increases the drying time. The other Liberon polishes do not contain additives. Both come in convenient 250 ml formats.
 
Au Naturel or Processed
You can purchase flakes in a waxed or de-waxed form. If you buy flakes that haven’t been de-waxed, the wax will settle to the bottom of the container, after being mixed with alcohol. However, you may have to let the mixture stand for a week or two, for this to happen. You’ll also have to be very careful when you pour off the liquid, so that you don’t disturb the wax. If you don’t remove the wax, the shellac will be less water resistant, and may also interfere with the shellac’s ability to bond with other finishes, such as varnish. De-waxed shellac only costs marginally more. If you plan to mix your own shellac, it’s probably a good idea to buy premium flakes from a reputable supplier, as there don’t appear to be any standards on flake production.
 
Coloured or Bleached
In its natural state shellac contains a reddish dye that can run the gamut from a dark caramel colour, all the way to a slightly orange tint. Any flakes with colour are collectively referred to as ‘orange flakes’. Manufacturers also bleach shellac to remove the colour; these flakes are referred to as ‘blond, clear, or white flakes’. Be wary of buying ‘seedlac’, as this is the coarsest variety, and contains a lot of impurities – bug and tree parts, dirt and the like. I keep some ‘garnet’ flakes on hand which I use to add warmth to dark wood, and ‘super blond’ flakes, which is the clearest shellac, and maintains the natural colour of lighter wood.
 

shellac_2
ColourFX concentrated dyes
 
You can also add an alcohol soluble dye to shellac, or you can stain over the shellac. I’ve had very good success using the ‘ColourFX’ concentrated dyes from Wood Essence. These lightfast dyes can be intermixed, and you can dissolve them in water, shellac, lacquer, or waterbased finishes. The nice thing about these dyes is that you can adjust colour intensity by varying the amount of solvent you use.
 
Making Your Own
Denatured alcohol is recommended as the best solvent to use, but is difficult to obtain. Alternatives are Isopropyl Alcohol (isopropanol or rubbing alcohol, the 99% pure version), Methyl Hydrate (methanol or wood alcohol), Ethyl Alcohol (ethanol or grain alcohol), or in a pinch, Mineral Spirits. Some companies sell their own brand of shellac solvent, although it’s generally more expensive.

The ratio of alcohol mixed with flakes is the “cut” of shellac. A 2 pound cut, which is a good mix to use, consists of 2 pounds of shellac flakes mixed with 1 gallon of alcohol. That’s quite a bit of shellac to mix, so you can proportionally reduce the mix to 4 ounces of flakes with 16 ounces of alcohol. You can buy an inexpensive scale to help you out, but you don’t have to worry too much about the exact measurement.

Mixing shellac is pretty easy. Begin by crushing the flakes. Then put your flakes in a glass jar (metal will cause the shellac to darken) pour in the alcohol, stir and cover. Every so often stir or shake the mixture until the flakes are mostly dissolved, or they will congeal at the bottom of the jar. Let the mixture sit for a day or two, then gently pour the mixture through a paint strainer, into a clean jar (there may be some wax in the bottom of the jar and you want to make sure it stays there). Now you’re ready to go to work. If you don’t use the shellac within six months or so of mixing it, throw it out and mix a fresh batch.
 
Shellac as a Sealer
Because shellac dries so quickly and is easy to sand, you can use it as a sealer to stop up pores and lock the wood fibres in place. It will lock in the oil in exotic woods as well. You can also use it over stains and dyes to keep them from bleeding through. Any finish (varnish, water based, lacquer, polyurethane) can be used over shellac; just make sure to use de-waxed shellac.
 
Applying Shellac
You can apply shellac by pad or brush, much like you would an oil finish or you can apply it using a ‘French polishing’ technique. (I will cover French Polishing in a future issue).
 

shellac_3
Cover wad, ensuring smooth bottom
 
You can simply squirt some shellac on a cloth and wipe the wood, or you can use a polishing pad. To make a pad, form a piece of cloth (cheesecloth, cotton, wool) into a wad about the size of an egg. Dampen the wad with alcohol, add a few squirts of shellac, then cover the wad with a piece of linen or muslin, ensuring that the bottom is smooth. The outer cloth can be replaced when it gets torn or dirty. The easiest way to apply the shellac is in a sweeping motion across the wood surface (with the grain). Use light pressure to begin, more pressure towards the end. The main thing to keep in mind is that shellac dries very quickly. Don’t worry if you miss spots. Let it dry an hour or so, then sweep another coat of shellac. Lay down at least three or four coats. You can sand lightly in between coats or after applying your last coat.

To brush shellac successfully you want to flow on thin coats. The best brush I’ve used for this is the ‘daVinci”, available from Wood Essence.


shellac_6


The very fine, soft hairs of this brush enable you to lay down an exceptionally smooth coat, with almost no brush marks. You can thin the shellac by adding solvent; this will make it easier to lay down the shellac. Before applying the shellac ‘condition’ your brush by dipping it in solvent and letting the solvent run off. Next dip the brush in shellac then tap it against the side of the container to unload the excess. Begin brushing a few inches in from the edge of your surface and drag the brush lightly to the edge then brush all the way to the other edge. You can brush back once if you need to even out the shellac. Overlap your next brush stroke just a little. I find that holding the brush almost vertical works best. Let the surface dry an hour and recoat. Lay down three or four coats. Sand lightly between coats only if there are brush marks. You can finish off with wax. Use solvent or household ammonia to clean your brush, followed by soap and water. In Canada, the sole distributor of Liberon, Color FX and daVinci is Wood Essence. 306.955.8775 www.woodessence.com
 
shellac_4
Cherry with three coats of Liberon pre-mixed polish – Easy French Polish
 

shellac_5
Garnet Polish


CARL DUGUAY is the web editor for Canadian Woodworking Magazine
Carl Duguay 2