This $5 Tree Sap Preserves Wood for 800 Years - Why Did Big Paint Bury This Recipe?

Added: 2026-05-19

[00:00:00]This church is 845 years old. The wood is original. It was alive during the Crusades. And it has been protected the entire time by $5 worth of tree sap. The global paint industry makes $12 billion a year. None of it uses this. In a clearing southwest of Oslo, a conservator named Lars Eric Hogan is supervising the production of $450 L of pine tar. He works with the society for the preservation of ancient Norwegian monuments. The kiln he is using is a stone lined pit partially buried sealed under a thick mound of turf and pete.

[00:00:38]The fuel inside is not firewood. It is the reinous hardwood and root mass of mature Scots pine. Scientifically pinos sylvestries harvested specifically for high resin content. The pete covering serves one purpose. It chokes off oxygen. A chemistry textbook calls what happens next destructive distillation.

[00:01:00]Without enough oxygen for full combustion, the pine does not burn. It pyrolyzes. Heat breaks the wood down into its volatile components and those volatiles drain out the bottom of the kil as a thick dark aromatic liquid. The process takes several days. A single kil burn yields about 450 L. That liquid is Stockholm tar. Sometimes called Norwegian tar, sometimes called pine tar. Through most of the 17th century, Stockholm was the largest tar export port in Europe, supplying the British, Dutch, and French navies. The wooden hulls of every major fleet in Europe were coded in it. By the 18th century, the trade had partially shifted to Finnish Austrobnia and the American colonies. But the Scandinavian process is the one the stave churches still rely on. Modern production almost lost one critical detail. When Norwegian conservators first reattempted full-scale taring in the 1990s, the tar refused to stick to the wood. It just beat it up. The fix was buried in a 19th century document discovered by conservator Inger Marie Eggenberg. The tar had to be cut with coal dust.

[00:02:13]Finally, powdered charcoal mixed in at the moment of application. The carbon particles bind to the wood fiber and locked the resin into the surface. That gap was a warning sign. The recipe was not just being lost. Pieces of it were already gone. The Norwegian state estimates it needs about 10,000 L of authentic Kilburn tar to maintain its remaining 28 churches on the current treatment cycle. The Swedes who used to lead the world in this craft have largely lost the tradition. Modern Swedish tragera is often blended with imported Chinese wood oil. It coats, but it is not the same substance. The original product is now produced at scale by perhaps a dozen small operations across Scandinavia and Finland. Pinear coverage runs 6 to 8 square meters per liter depending on wood pocity. At current retail prices of 20 to $30 per liter for authentic awesome or hisnitar, that works out to between $3 and $5 per square meter for a full coat. The retreatment cycle for exposed exterior wood is 6 to 8 years. A roof shingles needed more often. Wall panels less. Now, here is the part the brochures leave out. This is labor intensive. application requires heating the tar to lower its viscosity, typically to around 80° C, and brushing it in by hand. The applied surface smells like a woodfired sauna for about 3 weeks. It stains everything it touches. But the version you have heard that this is some ancient lost mystery is not the full picture. The recipe is still in print. The producers still exist. The composition is documented in peer-reviewed journals. By the end of this video, you will know the three companies that still make this product, what it costs to buy, what mixing ratio to use, and how it compares to the modern alternatives on your hardware store shelf. But none of that math means anything until you understand why the chemistry works. Pinear is not one substance. It is a mixture of several thousand compounds. The key actors fall into three groups. The first group is phenols specifically guacol creosol methylosol florol and pure phenol itself. These are small aromatic molecules with hydroxal groups attached to a sixcarbon ring. In the right concentration they are biocidal. They kill fungi and bacteria. The mechanism is not subtle. Phenols disrupt the cellular membranes of microorganisms and denature the enzymes those organisms use to break down wood. A fungal spore that lands on a tar surface is not slowed down. It is poisoned. And here is the part the paint industry would rather you not internalize. A latex or alkite paint film prevents wood from getting wet. If the film cracks or wears thin and moisture gets through, the wood is defenseless. Pine tar does not just slow moisture down. It carries a payload of biocy that stays in the wood fiber for years after application. The film can wear off. The kill effect remains. The second group is a resin acids, abiotic acid, pyic acid, dehydrobiotic acid.

[00:05:30]These are larger hydrocarbon based molecules. Their structure is nonpolar, meaning they present a hydrophobic surface to water.

[00:05:39]Water molecules do not bond to them. The water beats up and runs off. So in one substance you have two complete protection mechanisms. Phenols handle the biology. Resin acids handle the physics. The modern coatings industry needs two separate product lines to do half as much. The third group, the heavier polyaromatic residues weather slowly and remain in the wood as long-term reservoirs of resistance after the lighter volatile fractions have dispersed. This is published science not folklore. Ingger Marie Eggenberg working at the University of Goththingberg published her doctoral thesis on exactly this composition in 2003.

[00:06:19]The title was tearing maintenance of Norwegian medieval stave churches. She used gas chromatography and mass spectrometry to analyze tar samples taken from kilburns at different stages.

[00:06:31]and she correlated those chemical signatures to weather resistance over 30 months of natural exposure. The finding was specific. Tar drawn from the early stages of a kill burn has a different makeup than tar drawn at the end. The early stage tar performs better. Peer reviewed, instrumented on record in a Swedish university library. The conservatives of the Norwegian stave churches know exactly why their tar works. They can show you the gas chromatogs. There is a real limitation worth being honest about. The same phenolic content that kills fungi is mildly toxic to humans.

[00:07:08]Older preparations of pine tar contained enough phenol that prolonged skin contact was considered carcinogenic in early 20th century studies. Modern pine tar produced for skin therapy uses, things like dermatological shampoos and soaps is purified to remove most of the phenol. The construction grade product is not purified. You wear gloves. You do not apply it indoors. You do not apply it to surfaces that contact food. You might be wondering how something with that toxicity profile is permitted at all under modern regulation. The answer is that it was here first. Pine tar predates every wood coating regulation by about 900 years. And there is a reason it did not get squeezed out by industrial chemistry. That answer is coming. The most direct evidence that this technique works is a building called Ernest Dave Church on the Lostrafjord in western Norway. Dendro chronological dating the technique of matching tree ring patterns against the reference chronology places construction at 1131 to 1132. The supporting timbers are 894 years old. They are coded in pine tar. Pay attention to this next detail because it explains everything.

[00:08:21]The wood beneath the tar is not just preserved in some abstract sense. It is structurally sound. Conservators have taken core samples. The interior wood fiber tested in the 2000s was still fresh enough that researchers could identify the original X marks left by 12th century carpenters.

[00:08:40]Not rotted, not punky, not crumbling.

[00:08:44]The same wood that was alive in the era of the Crusades is still loadbearing today. Of the original stave church population in Norway, archaeologists estimate that nearly 2,000 once existed.

[00:08:56]Today, 28 remain. The Norwegian Directorate for Cultural Heritage tracks the maintenance of each one. Borgund in Saodan is the model the others are renovated against. Hedal is the largest.

[00:09:11]Hoerstad, also dated to 1131 to 1132 by researchers at the Norwegian University of Science and Technology, is the contemporary of Nest. The ones that did not survive did not die from rot. Most were destroyed in the population collapse following the 1349 black death and the lumber salvage that followed.

[00:09:31]Some were dismantled during 19th century church reform. The technique itself has never failed. Compare that to the current industry standard.

[00:09:41]A premium exterior acrylic latex from Sherwin Williams. The duration product line carries a manufacturer warranty of around 15 years on wood substrates. PPG Industries Permanizer line is comparable. These warranties carry exclusions for surface preparation, climate, and substrate movement. The actual field performance is typically shorter. Industry literature consistently records mean service lifetimes of architectural exterior coatings on exposed wood at 6 to 12 years in temperate climates before significant failure. That is not a small gap. That is roughly two orders of magnitude. A real caveat needs noting here. The stave churches are made from old growth Scots pine. The wood itself is denser, higher in natural resin and more decay resistant than most commercial soft wood available today.

[00:10:33]A modern fence built from kil dried plantation pine and coated in Stockholm tar will not last 800 years. The substrate matters. The tar can only protect what is there, but it will significantly outperform a modern stain on the same wood. Field testing by Norwegian Heritage Conservators has recorded service intervals of 8 to 15 years between recodes on tar exterior surfaces, depending on exposure. The same surface coated in a standard acrylic stain in the same climate would need replacement every three to five years. Run the math on cost over a 60-year service window and the numbers diverge sharply. Pine tar at $4 per square meter applied seven times over 60 years totals $28 per square meter in materials. Acrylic stain at $16 per square meter applied 12 times in the same window totals $192.

[00:11:32]That is before labor. There is a reason the industry does not encourage home owners to run that calculation. Hold that comparison in mind because we are about to look at exactly why the gap has stayed open this long. Step back from the church and look at the wider system.

[00:11:48]The global wood codings market was valued at 12.74 billion in 2024 by markets and markets research projected to reach 15.18 billion by 2030 at a compound annual growth rate of 3%. The dominant players are Sherwin Williams, PPG Industries, Exonobile, Excala Coding Systems, RPM International, Asian Paints, and Jotin. Sherban Williams alone reported $23.1 billion in trailing 12-month revenue in 2025 with an 11% net profit margin. The company controls Thompson's Water Seal, Cabbid Stains, Minwax, Dutch Boy, Kryon, Volspar, and HGTV Home by Sherwin Williams. PPG Industries reported $15.6 billion in revenue over the same period. Together, these two companies account for the majority of consumer wood coding sales in North America. That is a lot of paint. Read the business model on paper.

[00:12:48]Sherwin Williams Consumer Brands Group reports around 14% of total sales. The performance codings group, which includes industrial wood finishing, reports about 28%.

[00:13:00]The retail arm, recently renamed from the Pain Stores Group to the Americas Group, sells through more than 4,700 company operated locations and is the largest segment at 57%.

[00:13:13]The growth thesis presented to shareholders is built explicitly on repeat application volume. You would think someone would have said something, nobody did. The economic incentive is straightforward. A finish that lasts six years and needs recoding 10 times in a homeowner's lifetime generates 10 units of revenue. A finish that lasts 60 years generates one. The math is not hostile.

[00:13:38]The math is just math. But the math runs in the same direction every time across every quarter across every product category and the people responsible for keeping the math running know exactly which products threaten it. This is where the regulatory architecture becomes relevant. Pine tar is not a registered pesticide product in most US states states to sell it specifically as a wood preservative with biocidal claims a manufacturer would need to register the product under the federal insecticide fungicide and rodenticide act known as fifer with the environmental protection agency. Here is where the burial mechanism becomes visible. Data development to support registration of a new active ingredient routinely costs $10 million or more for a single major chemical. Total costs including service fees, chronic toxicity studies, environmental fate analyses, and residue testing can easily exceed 30 million. Pinear's biocidal properties have been known for 2,000 years. They are public domain composition. There is no patent to defend, no exclusivity to protect, and no commercial incentive for any single company to spend $30 million registering a product that any competitor can then immediately sell.

[00:14:55]So, nobody does. Pinear is sold instead as a wood stain or treatment oil with no claims about its fungicidal action permitted on the label. If you are wondering how something this effective is permitted to sit on the shelf labeled as decorative stain, so is everyone else who has read the regulatory history. The same friction does not apply to patented industrial formulas. A new acrylic resin or fungicidal additive developed by Dao Chemical BASF or Arma can be registered, branded, sold under trademark and protected by patents. The companies that own the chemistry recover their registration costs through pricing power. The companies that do not own a generic substance cannot. A patent filed under US patent number 10 million 264,794 covers compositions of unsaturated fatty esters used as carriers for creassote and pentaclorophenol wood preservatives.

[00:15:54]The patent describes existing formulations as effective but problematic due to volatile organic compound emissions, then claims a new formulation that reduces those VOCC's.

[00:16:05]The chemistry behind this patent is in functional terms a more expensive substitute for the volatile fraction already present in pine tar. The Swedish situation is worth noting as a control case. Sweden ran the global tar trade for three centuries. By the late 20th century, most of that production tradition had moved offshore. Modern Swedish pine tar manufacturers report importing wood oil from Chinese suppliers to blend with locally produced tar because the domestic supply chain shrank below the volume needed to support even niche demand. The Norwegians have been working to reverse that decline in their own market. As of 2025, only a handful of producers in Norway, Sweden, and Finland still make construction-grade Stockholm tar at scale. One more thing to be honest about, the industry has not deliberately suppressed pine tar in the sense of a coordinated effort. There is no smoke filled room. The mechanism is simpler than a conspiracy and more durable.

[00:17:05]There is just no money in marketing a public domain chemical that any backyard producer in Norway can make in a pete covered stone kill. That is the architecture of the burial, not malice economics. But the recipe alone does not help if you cannot source it. So here is where to buy it, what to mix with it, and how to apply it. Authentic kilburned pine tar is available from several producers.

[00:17:29]Ason AB in Mundal, Sweden produces genuine pine tar in 1, 3, 10, and 30 liter containers sold through marine and timber supply retailers in North America and Europe. Hisngera, also Swedish, makes a similar grade. West Coat Industries distributes in the United States. In Finland, Pinosoi is one of the larger producers. Alison on genuine pine tar retails between 25 and $40 per liter depending on volume. For exterior wood preservation, the traditional Scandinavian formula is one part pine tar, one part boiled linseed oil, one part natural gum turppentine mixed by volume. The linseed oil thins the tar and adds penetrating power. The tarpentine acts as a carrier solvent that evaporates after application, leaving the tar and oil locked in the wood. This threepart mixture is sometimes sold premixed as tar oil or Rosslex mahogany in Scandinavian retail.

[00:18:33]None of this requires special skill. The Norwegian conservators are using the same brush you have in your garage.

[00:18:40]Application requires preparation. The tar must be heated to between 60 and 80° C to reduce its viscosity from the consistency of cold molasses to something you can actually brush. A double boiler works. Do not heat it over an open flame. The vapors are flammable.

[00:18:58]The surface must be clean, dry, and bare wood. Existing paint or stain must be removed first. Pine tar cannot penetrate a sealed surface. It needs to soak into the wood fiber to deliver its biocidal payload. Get this step wrong and the rest of the project does not matter.

[00:19:16]Coverage runs four to six square meters per liter for the thinned mixture. About half that for straight tar. A typical exterior fence panel of around 2 square meters will consume between 350 and 500 ml per coat. Two coats is standard for new wood. Subsequent maintenance coats can be applied lighter. A cost comparison on a specific project. A typical residential cedar deck of around 30 square m. Premium acrylic deck stain at retail, two coats with a service life of about three years, runs roughly $180 in materials per cycle. Over a 30-year ownership horizon, that is 10 recodes at $180 each, totaling about $1,800 in materials, plus labor. The same deck treated with the traditional Scandinavian tar mixture. Two coats with a service life around seven years on horizontal exposed surfaces.

[00:20:15]Material cost per cycle around $60 to $90 depending on supplier. Five recodes over the same 30-year horizon. Total material cost roughly $450.

[00:20:27]A marine application makes the gap wider. A 30-foot wooden boat hull, traditionally retared annually, consumes about 10 to 15 L of pine tar. At $30 per liter, that is $300 to $450 per season in materials. The same vessel refinished with a modern marine varnish system, sanded and recotated annually by a professional yard, frequently invoices between $2,000 and $4,000 just for materials and shop time. The wooden ships of the Royal Norwegian and Swedish navies were tred for three centuries.

[00:21:03]The system worked. The math is the part that breaks the model. Once a homeowner runs the 60-year curve, the consumer relationship to the hardware store paint aisle is never quite the same. The honest limits. Pinear stains skin, clothing, and adjacent surfaces. It darkens wood significantly. Light colored wood will turn deep brown to black after a few coats. The smell is strong for 2 to four weeks after application before it dissipates. It is not suitable for interior use without serious ventilation. The FDA does not approve it for direct food contact surfaces. It will gum up brushes if you do not clean them with tarpentine immediately. And it does not provide UV protection in the way that titanium dioxide pigmented stains do. So heavily sunexposed surfaces will see surface oxidation that some home owners find aesthetically displeasing. Those are real limitations. They are also the same limitations that have applied to pine tar since the 12th century. The 12th century built the churches anyway. The Borgan stave church will be tred again in roughly 6 years. The Norwegian Directorate for Cultural Heritage budgets the work as routine maintenance.

[00:22:17]They have been doing it on the same building for 845 years. They will still be doing it on the same building long after no acrylic coating sold in a hardware store today is still on the market as a working product. What you have just been shown is a complete protection system that costs one quarter of the modern alternative, lasts more than twice as long between treatments, and has been continuously documented to work for nearly a millennium. The chemistry is public domain. The suppliers are listed. The application method has not changed in 900 years. The kils are still being lit in the forest north of Oslo. The papers are in the library at Goththingberg. The recipe is on the shelf in Osen's warehouse in Muldall. What endures is not what was loudest. What endures is what worked.

[00:23:06]You can buy a liter of it on