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Why Shellac Is My Go To Finish for Fine Furniture

Jul 5, 2016 | Expert's Corner | 0 comments

“I prefer to spray my shellac. Spraying shellac results in an even smoother finish which greatly reduces the amount of sanding during finish work.”

Rodney Dangerfield’s famous comedic catchphrase was, “I don’t get no respect.” In the world of furniture finishes, shellac gets no respect. That lack of respect is unwarranted. In fact, shellac is my “go to” finish on fine furniture. It should be yours as well.

The lack of respect for shellac may be due to the fact that it, a natural resin, is made from a bug’s secretions – not bug droppings, as some think. A lac insect, about the size of an apple seed, ingests tree sap which undergoes a transformation before being secreted as a shell-like shield that covers the bugs. The secretion also sticks to tree twigs. If it is scraped from the twigs, the result is known as “sticklac”, but if it is knocked free from the twigs using wooden mallets, the shellac is known as “grainlac.” Both are sent for additional processing.

As it is being processed, the story of shellac does not get any richer. Originally, shellac was ground in mills, sifted through screens then soaked in large containers of water. At some point a worker jumped into the containers and, with his feet, rubbed the shellac against rough-textured sidewalls to break open the seeds and release the bug remains. The concoction was then rinsed and spread onto concrete floors to dry. While this was how it all happen in the past, today the process is handled by machines.

Further disrespect for shellac could be because we do not realize its widespread use, most of which are not furniture-finish based. Shellac was and is used as sizing for men’s hats, printing ink, candy coating and adhesives. The closest we come to furniture finish is floor wax and shoe polish. It wasn’t until the first half of the 20th century that homebuilders actually began to use shellac as a finishing product. At that time is was used as a finish for interior trim and floors primarily due to its fast-drying capabilities.

The finish we see on shellacked woodwork in older homes is dark. This is not necessarily a result of the shellac, which is UV-resistant and does not change in color over time, it’s more a result of finish choices at the time. While early shellac was less refined (adding to the darker coloration) homeowners looked for a deep rich color so contractors tinted the shellac.

Today, many woodworkers find fault with shellac because of unused shellac that has been mixed degrades over time – that is another reason for the lack of respect. Degradation effects drying times and the film finish stays softer and is more easily scratched. Eventually, as the degradation continues, if you use outdated product, you end up with a gummy mess with which to deal. Experience taught me this lesson, so I watch my expiration dates closely. It’s best to keep shellac fresh.

Shellac is sold pre-mixed in cans or is sold in flakes that you mix, when needed, with alcohol. Since shellac has a shelf-life, it’s best if you know when your finish was mixed. Obtaining the date of mixture is easy when you mix your own shellac, but because you need time for the flakes to dissolve in alcohol, some woodworkers balk at mixing their own.

Pre-mixed shellac, in the United States, is sold by Zinsser. Zinsser shellac has a company-reported shelf-life of three years from the date of manufacture. The company provides codes printed on the can lid that indicate the date of mixture, but you have to decipher that code.

A typical code found on a can lid might be S0720BD. The first number after the letter is the year the shellac was mixed. In this case, you see 0 which indicates 2010. If the number was 1, it would represent 2011, and 2 would indicate 2012. The first number after the year indicator is the month of mixture. In the example, 7 indicates the month of July. The numbers 1 through 9 stand for January through September, 0 indicates October while N is for November and D for December. If you need more in-depth information, the two numbers that follow the month indicator tell you the exact date of manufacture.

Another reason that woodworkers lack respect for shellac stems from the many myths that surround this finish. Myths such as, shellac is difficult to use, lacks water resistance and is incompatible with other finishes. These beliefs are simply not true.

Shellac is not only simple to use, it is easy to repair. Once mixed, either from flakes or directly from a can, shellac can be brushed on, ragged on or sprayed onto your project. If you brush shellac, use a good-quality brush. A good brush carries more shellac to your project and that allows you a better flow of the shellac for a smoother finish. This idea is the same for most any brush-applied product. Also, fast drying times allow for more coats to be applied daily (a faster finish process) and keeps shop dust out of your project.

I prefer to spray my shellac. Spraying shellac results in an even smoother finish which greatly reduces the amount of sanding during finish work.

Lack of water resistance has long been a stab at shellac. Hhowever, fresh shellac is remarkably water resistant. Shellac will develop white rings from glass condensation, but only after hours of neglect. And the truth is that much of the necessary water protection should come from a protective coat of wax.

Lack of compatibility is my favorite shellac myth. In nearly 20 years of working with shellac – from flake and store-purchased – I ran into a problem once when I added a layer of lacquer over a coat of shellac.

Compatibility is no problem at all if you’re about to add shellac over an earlier coating. In fact, I have yet to see shellac not adhere to any base coat, especially if you scratch the earlier layer to prepare for your shellac. Simply put, shellac covers all.

Working the other direction or when you apply other topcoats over shellac, it is often noted that you should not apply polyurethane over shellac. My personal opinion is that you should not use polyurethane, at all. But with that quick step on and off of my soapbox, I will say that even the company recommends that you do not use a polyurethane over shellac, but many woodworkers do this on a daily basis without any concerns. It is, however, OK to use an oil-based urethane over shellac.

Other than polyurethane, I have not heard nor experienced any problems with adhesion to shellac except for the lacquer mentioned above. To clarify that situation, I had used amber shellac to warm a cherry finish – one of my favorite finishes for cherry and walnut – when I sprayed on my first coat of dull-rubbed effect lacquer, there were two areas the size of a half-dollar that peeled off. I can only surmised that my shellac or my lacquer were close to outdated, or that those two areas contain a higher concentration of wax. A simple fix would have to apply a coating of dewaxed shellac prior to moving to my lacquer.

Just as Mr. Dangerfield was a much beloved comedian/actor who had a lengthy career, shellac, once hailed as the best finish for fine furniture, has been around for a long time. It has stood the test of time. If not for the furniture factories who want to switch to a “new and improved” product while dumping what was considered an “old-fashioned” finish, furniture makers today would not have to rediscover this great product. If you have not worked with shellac, do yourself a favor and try it. You will be delighted.