We recently completed a project for a great customer who had saved a variety of cypress boards that she wanted incorporated in her new home office shed. We used the wide cypress planks to build the desk and shelves, and installed the random width pecky cypress on the ceiling of the 12’x14′ shed. Pecky cypress is created when a tree is attacked by fungus, resulting in lens-shaped pockets throughout the wood. Studies have not revealed the exact origin of the fungus or why it attacks only certain trees. The resulting boards have a unique texture that creates a rustic but elegant look.
At the owner’s request, we coated the cypress with shellac which brought out the grain of the wood, giving it a richer finish. While we have used shellac on other projects, this was our first opportunity to use the product in one of our sheds and we couldn’t be more pleased with the results (and the customer was pretty happy too).
|You can see the difference the shellac makes on the raw wood in one coat|
|The finished ceiling|
Shellac is a natural, organic resin that is secreted by the small Lac bug (Laccifera lacca). This bug lives on certain trees indigenous to India and Thailand, feeding on the sap that it sucks from the twigs of these trees. The bug creates an amber colored resinous substance that forms a cocoon to incubate the eggs she lays. This cocoon is the raw material for shellac and is called “sticklac”, because it contains resin, parts of the twig and bug remains. The sticklac is washed and then refined either chemically or by hand, to produce the raw material available for sale to commerce. The raw material consists of dry flakes that are then dissolved in denatured alcohol. Once dissolved, the liquid shellac has a limited shelf life.
Shellac was the preferred wood finish for wood floors, and wood paneling up to the mid 20th century. It comes in many warm colours, ranging from a very light blond (“platina”) to a very dark brown (“garnet”), with all shades of brown and yellow and orange and red in between. The colour is influenced by the sap of the tree the lac bug is living on, as well as the time of harvest. Historically, the most commonly-sold shellac is called “orange shellac”, and was used extensively as a combination stain and protectant.
An interesting feature of shellac is that it resists water-vapor very well. In tests done by the United States Forest Products Laboratory on the moisture-excluding effectiveness of wood finishes (the ability of a finish to prevent moisture vapor from entering the cellular structure of the wood – called MEE), shellac rated above polyurethane, alkyd and phenolic varnish and cellulose-nitrate based lacquers.
Some facts on shellac:
- It takes about 100,000 lac bugs to make 500 g of shellac flakes.
- Shellac is UV-resistant, and does not darken as it ages (though the wood under it may do so on its own, as in the case of pine)
- Shellac scratches less easily than most usual lacquers, and damaged areas can easily be touched-up with another coat of shellac (unlike with polyurethane) because the new coat merges with and bonds to the existing coat.
- Shellac is FDA approved — safe for food utensils and children’s toys
- Shellac has low toxicity/ fumes.
- Shellac is used to provide protective candy coatings or glazes on candies like Reese’s Pieces.
- Shellac mixed with marble dust is used by lamp manufacturers to glue the metal base to glass incandescent bulbs.
- Shellac is used to stiffen felt used to make hats.