Sunday, September 11, 2022

Tad Spurgeon, Linseed Oil, and Living Craft

 Note: If you're looking for Tad's PDF on oil refining, or his book, they're posted at the bottom.

 When I first started researching traditional varnishes and oil finishes, one name that kept popping up was Tad Spurgeon. He's well known in the art world, but I suspect few woodworkers--with the exception of violin makers--have heard of him. His website is regrettably shutting down at the end of this month (9/22), so I wanted to give him a proper sendoff, and also post some materials (with Tad's permission) that readers can download and explore if they're interested.

Tad is a very accomplished painter, but he's perhaps best known for having almost single-handedly  revived the ancient practice of washing linseed oil. You are probably wondering why on earth anyone would want to wash linseed oil. There's a long answer…but the short answer is that a washed oil dries in about half the time of raw oil, will yellow or darken less, and be far less susceptible to mold or mildew. So if you are using oil as a primary finish, or using it to make varnish or paint, your results will be better.

Spurgeon started washing linseed oil because he wanted to make his own paint. Today, most artists go to an art store to buy paint made in a factory, but before the 20th century, artists generally made their own paint. Unsatisfied with the answers he got from 20th century writers, Spurgeon turned to sources such as the 17th century De Mayerne manuscript, and to a pair of important 19th century texts by Eastlake and Merrifield. He found that prior to the 19th century, artists typically used cold pressed, hand washed oil to make paint and varnish their canvasses, and that many of the paintings had lasted centuries without appreciable darkening or deterioration. But in the 19th century, as the use of hot pressed, industrially refined (or unrefined) oil proliferated, darkening became common, and by the 20th century, artists' textbooks treated it as a given. 

Over a period of years, Spurgeon experimented with the oil washing methods described in the older sources, and rigorously recorded his results. In some cases he was able to systematize older methods and make them more efficient, and he also developed some entirely new methods. He also explored--and again thoroughly tested and documented--related methods of processing such as heat treating, oxidizing, and aging in sunlight. All of this is laid out clearly and concisely in the Oil Refining PDF at the bottom of this post, and it's well worth checking out.

For woodworkers, the linseed oil research is the most directly applicable part of Spurgeon's work, but for him it was just the tip of the iceberg. In his book Living Craft, he reconsiders the totality of the painter's materials in the same vein, and seeks to reestablish a craft based on handmade materials, in sharp contrast to the modern practice of using purchased materials. 

I'm a woodworker, not a painter, but Spurgeon's work has influenced mine in a number of ways. First, there's the idea that using handmade materials changes your relationship to the craft. As a toolmaker, this notion already had resonance for me--I've made most of the planes, floats, and other specialty tools that I use in my daily work. But formulating my own finishes out of hand-processed oils and natural resins added a new dimension to the work: Finishing becomes a much more integral part of the process, and one that has more meaning, when you're not just buying a bottle of mystery liquid at the hardware store and slapping it on.

Second, Spurgeon serves as a model for how to approach research as a craftsman, rather than as a scientist. His tests of materials don't pretend to be formal scientific experiments--and they're the better for it. Over the years, I've seen many attempts to do scientific tests related to woodworking--on finishes, on tool steels for chisels, on planing angles, you name it. They usually fall flat, either because the designers lack expertise in the craft, or because they try to remove any trace of the human hand, in a misguided effort to ensure objectivity. Building a machine to chop particleboard with a chisel, for example, may seem more objective than having an experienced woodworker chop dovetails in maple all day, but it's not very useful for telling us about the feedback the chisel gives the hand, about how difficult it is to resharpen, or how well the tool integrates into normal workflow. In a similar vein, tests on linseed oil that use advanced imaging or analysis methods may look impressive, but if the experimenter doesn't have real experience using and processing the oil, and just uses any old oil off the shelf, the test is likely worthless, because not all linseed oils are the same.

Which brings me to one of Spurgeon's most important insights, which is that many basic materials that we take for granted are fundamentally unlike their historical versions. Linseed oil is a great example, but there are many others…turpentine, for example. That noxious substance that you buy at the hardware store is so unlike traditionally made turpentine that it doesn't deserve to be called by the same name.

Spurgeon isn't the only one to discover this: In many ways, his thought parallels Michael Pollan's writing about food in The Omnivore's Dilemma, In Defense Of Food, and elsewhere. And that's not a coincidence. As Pollan shows, the industrial system of production that has developed since the late 19th century has fundamentally transformed our food, from flour and tomatoes, to chickens…and the same is true of linseed oil and turpentine. The food industry and the coatings industry are two sides of the same coin, and both are built, as Pollan might say, on the same, slowly sinking sea of cheap petroleum.

That's a depressing thought, but as Spurgeon dryly notes in Living Craft, we still have opposable thumbs. So, if you want to taste how different a real tomato is from the industrial crap at the supermarket, get a Brandywine plant (or some other heirloom variety) and grow it. And if you want to experience how different good linseed oil is from the crap at the hardware store…well, download Spurgeon's writings below, and get cracking.




  1. Thanks for sharing. In 2001, I was between jobs as an organic chemist. It was shortly after 9/11 and no one was hiring for a while. Though a mutual connection I got a job as a consultant for a lubrication company. They were taking natural oil, partially polymerizing them and finding uses for them in both beauty products, cutting cooling/lubricating fluids, and motor oils.

    One of the techniques used to clean up the oil prior to use for cosmetics was to steam sparge it. Meaning, hot steam was bubbled through the solution while it had a vacuum pulled on it. Sort of like a steam distillation. It removed volatile compounds with odors. After that, we heated it for a while to increase its viscosity (presumably through Diels Alder reactions which is what I think happens to Lindseed oil when making stand oil). The prior steam sparging also helped the viscous oil become less yellow.

    If I had to guess, a similar thing is going on with rinsing Linseed oil with water. A really common technique I have done thousands, if not tens of thousands of times, was extraction with a separatory funnel - very common for organic chemists to do so. I'm guessing is what is going on is that aqueous soluble compounds (small organic acids) are being extracted. Looking forward to reading the PDFs. Also curious of bicarb solutions were tried as that would greatly increase the solubility of organic acids into the aqueous layer. Fun stuff. Thanks for sharing.

    1. I had a chance to read the PDF since my first post above. It is very well done and much more comprehensive than I expected it to be. Can't wait to try it. Any chance you can get in touch with Don Williams and see if he will put this info "permanently" on his website? He has an area that has a lot of great info on shellac and I think it would be great if this info were co-located near that.

    2. There are a lot of ways to refine oil, but most commercial refining removes the oxidants as well as the antioxidants, so it dries slowly. I've done many tests on glass, and alkali refined oil dries in about 90% of the time of raw oil, while saltwater washed oil dries in half the time.
      Regarding Don, I don't own the PDF, Tad does, so it's not mine to distribute. But, the files do have a permanent home--right here. That is really the point of this post--anyone who searches for Tad Spurgeon should be able to find it.

  2. Thank you for this (and for hosting the links). And of course thanks to Tad Spurgeon as well.

    The "salt and sand" process of refining linseed oil worked quite well for me and provides a pleasant, low-yellowing finish. Aging the oil in the sun was a good long-term project for me. Seeing the progress over the weeks and months was comforting during the last couple of years. I look at my stash and wish I was using more of it, so I could repeat the process sooner.

    1. I use the salt/sand method too! There's no reason you can't refine a bunch of oil now, and save it for years. You can store it for decades in a full jar, or a couple years in a partially full jar (it will thicken, and dry faster).