A Short History of How Shellac Became Known as a Sealer - Popular Woodworking Magazine

A Short History of How Shellac Became Known as a Sealer

 In Flexner On Finishing, Flexner on Finishing Blog

Zinsser also changed the name of its “orange” shellac to “amber” shellac (who wants orange wood?) and its “white” shellac to “clear” shellac.

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 as I have experienced it centers 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, 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 think they should always use shellac as the sealer.

– Bob Flexner

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Showing 11 comments
  • Joe Leonetti

    I primarily use shellac then wax to finish my pieces. It’s easy to use and looks good.

  • Dan

    To be honest, I like starting with shellac because it’s fast & easy but I too fell into the sealer myth.

  • wildgrain

    Thanks for your blogs Bob. You always clearly demystify wood finishing. I use super blonde de-waxed shellac to warm up a water borne top coat. I believe you have recommended this in the past, do you still recommend this (vs tinting the top coat, or other process)?. I have read your 2005 book, and would love to hear your 2017-updated opinions on the best water borne finishes. Thanks again!

    • Bob Flexner
      Bob Flexner

      I don’t really have an updated opinion on the best water-based finishes. I don’t think they have changed all that much. The reason, of course, is the inclusion of water, and it’s the water that causes most of the problems and difficulties with application. It’s been my experience that most people who change to using water-based finishes do so because of the much reduced odor. (Of course, the reason industry changes is often to comply with VOC laws.) If you use a brush for application, clean up is also easier, just as with latex paint. If you use a spray gun for application, clean up is considerably more difficult than with lacquer. I believe I covered all of this in 2005.
      There are lots of methods of warming the color of water-based finishes. Using a coat of shellac is one of them, and a good one if it produces results you like.

  • 1995gm

    Bob, I agree there are other ways to washcoat wood than shellac. It is unfortunate that shellac is considered useful only as a sealer. I use shellac for various finishing processes and to make my own stains . I have been experimenting with button lac lately.

    As you stated, the longer drying/cure of varnish based wash coat leads to user error. Maybe they suggest shellac because they think their readers are impatient?

    Also, instructions on Rust-Oleum Ultimate stain state that no conditioner is needed. They claim use of nano pigments for more even coverage.

    Bob, do you get blotching if you use dyes without a washcoat?
    I have been experimenting with dyes. I get varying blotching results depending on whether I use oil, alcohol, or water based dyes. Alcohol based dye with a splash of shellac in the solution has given me the best results so far.

    • Bob Flexner
      Bob Flexner

      All stains blotch wood that is prone to blotching – pine, cherry, etc. Gel stains don’t blotch pine very much because the stains are thicker. By adding shellac to alcohol dye, you are thickening it.
      Concerning Rust-Oleum, I refer you to my April, 2015 (#217) article in Popular Woodworking where I tell the story of Olympic Stain claiming blotch resistance because of “absorption control.” The wood example they used in their ads was oak, which doesn’t blotch! Manufacturers like to claim they are giving us what we want.

  • Saville

    I like to use dewaxed shellac for “sealing” (if that’s the right word) the end grain of wood so that it doesn’t soak up more stain than the surfaces, and therefore look darker.

    I would add this to your “odors” and “resin in the wood” reasons

  • truspark

    I’ve always read that using shellac as a base coat is a good reducer of blotchiness in a finish as it pertains to pine, maple, birch and cherry. I didn’t see that mentioned in the article.

    • Bob Flexner
      Bob Flexner

      Think about your comment for a moment. The purpose of a thinned first coat is to block the deep penetration of a stain so that blotchiness is reduced on the woods you mentioned. So what would make shellac better than any other finish in accomplishing this? Nothing. All finishes do this the same. In fact, the common product called wood conditioner is simply thinned varnish. It performs well if you let it dry thoroughly before applying the stain. (This is not what the directions say, which is the reason so many people are unhappy with this product – varnish takes much longer to dry than shellac.) Industry uses thinned lacquer to reduce blotching. The very fact that you have been led to believe that there is something special about shellac for this purpose illustrates well the point I was making.

      • truspark

        Thanks for the reply Bob. I must admit your book was one of the first that i read when I started woodworking, but I knew nothing back then so little sunk in. Then I spent the last 8 years just trying to perfect my joinery techniques so I’m just now starting to focus on finishing, so please forgive my ignorance.

        So an example, I have this Rustoleum walnut stain. Are you say that I could just thin that stain with mineral spirits (50%?) and apply a thin coat to pine and that would be effective enough to minimize blotchiness on the next full coat?

        • Bob Flexner
          Bob Flexner

          No. I’m not saying that at all. The idea is to block deep penetration of the stain by applying a first coat of finish that you have thinned with one-to-two parts thinner. You should probably experiment on scrap. But you can never totally eliminate the blotching because the clear finish itself will highlight some of it.

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