Here’s a short history of shellac, some of it from my own experience.
Shellac was almost the only finish used on furniture from the 1820s to the 1920s when nitrocellulose lacquer was introduced. Shellac continued to be used widely as a complete finish by painters working in buildings until the 1950s.
By the 1990s the only remaining supplier of shellac in liquid form was Zinsser, which sells the shellac under the brands “Bulls Eye,” and “SealCoat,” which is a dewaxed variety. Zinsser specializes in sealers and primers, so it markets the shellac as a sealer.
The marketing strategy seems to center on getting influential magazine and book writers to recommend shellac as a sealer. This has led to shellac becoming widely identified as a sealer rather than as a complete finish.
Too much so, in my opinion, both because shellac still makes a great complete finish just like it used to, and because there’s no reason to use shellac as a sealer unless there’s a problem you need to seal off. The four common problems are:
- Silicone contamination in the wood from the use of certain furniture polishes. This contamination causes the finish to fish eye, which shows up as ridges, often in the shape of craters.
- Oil or wax on the wood. Shellac bonds better than other finishes to oily and waxy surfaces.
- Odors in the wood – for example, from smoke damage or animal urine. Shellac blocks these fairly effectively.
- Resin in the wood, especially from pine and other softwood knots and in certain exotic woods that grow in jungles. Examples include teak, rosewood and cocobolo. Shellac also blocks this resin fairly effectively.
Notice that except for the last one, the problems are typically refinishing problems. Also notice that all the major writers on finishing are, or were at one time, professional refinishers. So shellac was a very useful tool for them (us).
But shellac is not necessary if these problems don’t exist. And this is the point of this short history. No furniture or cabinet manufacturer uses shellac as a sealer. Only woodworkers who read the magazines, or are told by someone who does, think they should always use shellac as the sealer.