The History of Shellac, Part 4: An Enduring Finish

The History of Shellac — a four-part series
Part 1: An Ancient Resin · Part 2: A Brilliant Century · Part 3: A Fading Shine · Part 4: An Enduring Finish

The Modern Form — and What Changed After WWII

Here the story turns on a point of chemistry that most modern finishers don't know.

Before World War II, essentially all shellac was processed thermomechanically — the bag-and-fire method that produces button lac and wax-containing flake. The wax content of pure shellac processed this way was modest: Walker and Steele, using petroleum-ether extraction methods they developed specifically for this purpose, found approximately 6% petroleum-ether-soluble fraction in pure, unmodified shellac — this is the analytical figure for natural wax content. (Some practitioner estimates run considerably higher, but analysis does not support those numbers.)

The mid-twentieth century introduced something different: solvent dewaxing. Rather than pressing seedlac hot through cloth, industrial refiners began dissolving seedlac in solvent and using petroleum fractions to selectively extract and remove the wax before drying the resin into flakes. The result — dewaxed shellac flake — is useful and has real applications. It adheres well under polyurethane topcoats, which wax-containing shellac does not. It builds a harder, clearer film in applications where the wax's contribution is a liability rather than an asset.

But it is a different product from what every historical finishing text describes. When Stalker and Parker wrote about shellac varnish in 1688, they were describing thermomechanical product. When the French polishing manuals of the 1820s described shellac's behavior under the rubber, they were describing thermomechanical product. When Walker and Steele analyzed shellac's properties in 1922, they were describing thermomechanical product. No peer-reviewed study has directly compared the film properties of thermomechanical button lac against modern dewaxed flake side by side — the question is open. What is established is that they are not the same material, and that the classical finishing literature describes one of them.

For practitioners attempting to match period finishes — museum conservators working on eighteenth-century furniture, French polishers restoring Victorian cabinetwork, luthiers building instruments in the tradition of Torres or Hauser — button lac is the period-correct input. Seedlac, the washed and graded form before the final pressing step, is useful for practitioners who want to work with the pre-button material directly and control the filtration themselves.

What Survives and Why

Button lac never disappeared entirely. The British French polishing tradition — centered in High Wycombe, London, and the furniture-making Midlands — maintained a continuous market for button polish through the worst decades of shellac's contraction. The antique restoration trade, where there is no acceptable substitute for a material that matches the original finish, sustained demand at a professional level. The luthier community, in which French polishing is the expected technique for classical and flamenco guitars and many orchestral instruments, kept the specific properties of button lac in active practitioner knowledge.

In recent decades, the craft woodworking revival — hand tools, period techniques, historical finishing brought back into practice through publishers and communities that take traditional work seriously — has brought a new generation to shellac generally and to button lac specifically. These are not casual hobbyists. They are practitioners who have done enough finishing work to care about the difference between thermomechanical and solvent-processed shellac, between wax-containing and dewaxed, between the warmth of an amber film and the neutrality of a blonde one.

It is the same audience that serious cabinetmakers and French polishers have always been. The supply chain that serves them shrank considerably over the twentieth century. But the practitioners and their questions did not go away.

The Catalog

What we carry starts with this history. The button lac we sell is pressed by trusted cottage producers from seedlac we control at the source — the only way to guarantee purity against a two-hundred-year-old adulteration problem. The seedlac is the unwashed precursor, for those who prefer to work from that stage. The wax-containing flake is thermomechanically processed shellac in its most accessible form. The dewaxed flake is there for applications where the absence of wax is specifically what the work requires.

Each product has its place in the history above. Each has a specific character and a specific set of applications for which it is the right choice. The long story of shellac ends, for the purpose of this catalog, in one simple claim: we know what we're selling, we know where it came from, and we know why it matters.

Sources: Walker & Steele, "Shellac: Source, Manufacture, Uses, and Testing," NBS Technologic Paper T232, Bureau of Standards, 1922. Zinsser, William, "The Story of Shellac," Zinsser Company, 1913 (revised 2004). Stalker, John and Parker, George, A Treatise of Japanning and Varnishing, Oxford, 1688. Roubo, André Jacob, L'Art du Menuisier, Académie des Sciences, Paris, 1769–1774. Siddons, George A., The Cabinet Maker's Guide, 1825 (US edition 1827). Khan, Sheikh & Ali, "Historical Orientation of Craft and Dissimilar Regional Styles of Lac-Turnery in Pakistan," IJMCR Vol. 9, 2021.