What is Pine Tar?

Pine Tar at a Glance

Pine tar is a dark, penetrating wood preservative made by slow-heating pine stumps and roots until the resinous liquid drains out. Woodworkers have used it on fences, barns, tool handles, and boat timber for over a thousand years. It soaks into the grain and protects from the inside. No hard surface coating, just a deep treatment that keeps outdoor wood from rotting, splitting, or drying out.

In this guide:

• What pine tar is and how it's made
• Where it works best and where to skip it
• How it compares to linseed oil, polyurethane, and PT lumber
• How to apply it and what to buy

Click to expand

Part 1: What Pine Tar Is

Pine tar comes from pine trees, but not from tapping living trees. It's produced by heating pine stumps, roots, and heartwood in an oxygen-restricted environment until the resinous liquid separates and drains out. The process is called destructive distillation (or pyrolysis), and the chemistry is the same today as it was when Scandinavian craftspeople first built earthen kilns to produce it.

Click to expand

How it's made

The traditional method: pine wood (split into finger-sized pieces) gets packed into a stone or earth kiln, sealed tightly, and fired slowly from below. Without oxygen, the wood doesn't combust. It breaks down into its components, and the tar drains from a hole at the bottom. Modern production uses industrial kilns with better temperature control, but authentic pine tar still contains no petrochemicals, solvents, or additives. What comes out of the kiln goes into the container.

The smoky, resinous, campfire-like smell comes from the volatile phenolic compounds released during this process. Those same compounds are responsible for pine tar's preservative properties.

What's in it

Per Wikipedia's pine tar entry, the material is a complex mixture. Its key components:

• Phenolic compounds (guaiacol, creosol, phenol): the antiseptic and antifungal agents
• Resin acids (dehydroabietic acid): bind to wood fiber and provide water resistance
• Terpenes (alpha-pinene, beta-pinene): penetrating carriers that help the material travel deep into the grain; also the source of the characteristic smell
• Aromatic hydrocarbons: contribute to long-term durability and adhesion

Density runs 1.03–1.07 g/cm³ (slightly heavier than water), and the consistency ranges from heavy motor oil in warm temperatures to nearly solid when cold. This is why application temperature matters.

Color varieties

Not all pine tar looks the same:

• Green pine tar: produced in closed kilns from living pine wood; lighter color with a greenish tint; creosote-free; often marketed for sensitive applications
• Black pine tar: from aged pine wood with full processing; deep black; strongest smell; maximum phenol content
• Brown/dark pine tar: intermediate processing; common in Scandinavian building traditions

All three darken the wood upon application. The degree depends on product type, wood species, and how many coats you apply.

Part 2: A 1,000-Year Track Record

Before synthetic wood preservatives existed, pine tar was how you kept outdoor wood alive. The evidence isn't anecdotal. It's architectural.

Viking ships and medieval churches

According to archaeological research published in Antiquity, pine tar production and trade goes back to the Viking Age in Scandinavia, with evidence of large-scale kiln networks supplying refined wood tar to trading centers across northern Europe. Viking ships were preserved with it — the hulls, the rigging, the hemp rope. Traditional Scandinavian wooden churches, some still standing after 800 years, were treated with pine tar mixtures.

Sweden scaled production to an export industry. By the late 1600s, tar was Sweden's third most valuable export commodity, with exports reaching 227,000 barrels annually at peak. "Stockholm tar" — named for its export hub — became the benchmark for quality in European naval shipbuilding. The maritime history record at maritime.org documents how the Royal Navy specified it for hull preservation.

Click to expand

Why this matters for your fence or tool handles

A material that kept Viking ships intact on the North Sea through repeated freeze-thaw cycles and saltwater exposure for a decade at a time is credible for your fence posts. The chemistry hasn't changed. The same phenolic compounds that prevented rot on medieval ship timber are what you're applying when you brush pine tar onto an axe handle today.

Part 3: How Pine Tar Protects Wood

Penetrating, not film-forming

Polyurethane builds a hard film on the surface of wood. Pine tar doesn't. It penetrates into the grain, travels down into the fiber structure, and establishes protection from inside.

Pine tar doesn't create a scratchable surface. If you drag something sharp across pine-tarred wood, you're scratching wood, not a protective layer. The wood can still breathe — moisture moves in and out without being trapped under a film that can crack, peel, or blister. Film finishes fail at their edges; pine tar treatments fail gradually by wearing thin, which is why you can maintain them without stripping.

Click to expand

What the phenolic compounds do

The antiseptic and antifungal properties come from the phenols: cresol, guaiacol, and phenol itself. These compounds inhibit the bacteria and mold organisms responsible for wood rot. They're the same class of compounds in many hospital disinfectants, acting here at lower concentration over a longer time frame.

Pine tar also provides UV protection. Ultraviolet light breaks down lignin (the structural polymer that holds wood fibers together) and causes surface graying and degradation. The aromatic compounds in pine tar absorb UV radiation and slow this process. Combined with moisture resistance from the resin acids, this is why pine-tarred fence boards from the 1970s sometimes look better than untreated boards from last decade.

Finally: the phenols and terpenes deter wood-boring insects including carpenter ants, termites, and wood bees. This isn't a claimed benefit. It's documented in the literature and confirmed by generations of practical use.

Longevity and maintenance

Initial treatment: two coats, 24 hours apart, gives a full foundation. On structural outdoor wood in a temperate climate, that treatment typically lasts five years before the next coat is needed. After the first maintenance coat, the cycle extends to every ten years.

This is better longevity than most penetrating oils and comparable to exterior paint, but without the paint's failure mode. When pine tar wears thin, you add a coat. You don't strip it, sand it, or start over.

RELATED: Boiled Linseed Oil BLO is the standard partner for pine tar in the classic 50/50 outdoor formula, and it shares the same spontaneous-combustion hazard for soaked rags.

Part 4: Where Pine Tar Works Best

Pine tar excels in specific conditions and fails in others.

Click to expand

Where it earns its place

Fences and fence posts — including wood in ground contact. Pine tar is one of the few natural finishes that holds up in soil-contact conditions. Most finishing oils can't touch this application.

Barn siding, log cabins, outbuildings — exterior wood cladding exposed to rain, UV, freeze-thaw cycles. The Scandinavian tradition of tarring wooden buildings wasn't decorative; it was structural maintenance, and it worked.

Tool handles — axe, hatchet, hammer, shovel. Traditional woodworkers have treated handle wood this way for centuries. The classic method: dip the eye end of the handle in hot pine tar before fitting the axe head. It lubricates for assembly, prevents water entry, and helps the head seat tighter over time. Hults Bruk — a Swedish axe manufacturer operating since 1697 — recommends pine tar for handle maintenance specifically because it penetrates the grain rather than sitting on the surface. For ongoing maintenance, a thin coat brushed or rubbed onto the handle preserves the wood and provides grip.

Outdoor furniture on unfinished wood — not over an existing finish, but on bare, dry wood. Tables, benches, Adirondack chairs in raw wood.

Raised garden beds — pine tar is one of the few wood treatments appropriate near vegetable gardens. No copper-based biocides, no arsenic, no petrochemicals. For planters or beds where the treated wood will be near soil and food crops, this matters.

Boat timber (above-waterline exterior planking, decks). Not a hull treatment for fiberglass, but for traditional wooden boat maintenance, pine tar mixed with linseed oil and turpentine is a classic approach.

Where to skip it

Indoor furniture and interior woodworking — the smell is the dealbreaker. Even after curing, the smoky scent lingers for one to two weeks. Acceptable on an outdoor fence; not acceptable on a dining table in your living room.

Surfaces with existing film finishes — pine tar won't penetrate through polyurethane, paint, or varnish. It sits on top and makes a sticky mess.

Fine finishing work — pine tar produces no sheen, no smooth surface. It's a preservation treatment, not a furniture finish. If you want a clear, glossy, or satin surface, look at polyurethane or mineral oil.

Spray application — the viscosity and tackiness of pine tar makes it unsuitable for spraying. Brush or cloth only.

Part 5: Pine Tar vs. Modern Finishes

Most comparisons between pine tar and modern finishes miss the point. They're mostly doing different jobs.

Pine tar and linseed oil are partners, not competitors

The standard application formula is 50% pine tar, 50% raw linseed oil. These two materials are complementary, not alternatives. Raw linseed oil thins the pine tar and improves penetration into the grain; pine tar adds antifungal and antiseptic properties that linseed oil alone doesn't have. The combination outperforms either material individually on outdoor structural wood.

A formula used for tool handles: 8 parts boiled linseed oil to 1 part pine tar to 1 part turpentine. The turpentine speeds penetration and drying; the proportions can vary based on application.

Pine tar vs. polyurethane

These aren't competing for the same jobs. Polyurethane is a hard film finish designed for surfaces that need abrasion resistance: floors, tabletops, interior furniture. It works indoors and outdoors; outdoors-rated poly holds up well on decking when applied and maintained properly.

Pine tar is a deep treatment for outdoor structural and working wood. No sheen, no scratch resistance, no indoor application. If you're finishing a dining table, polyurethane wins. If you're treating barn siding or a fence that will be in the ground, pine tar wins.

Pine tar vs. pressure treated lumber

Pressure treated (PT) lumber uses copper-based chemical preservatives (formerly CCA with arsenic; now ACQ or CA-C). These are effective and long-lasting. PT lumber in ground contact can last decades without treatment.

Pine tar is a valid natural alternative where chemical exposure matters: raised beds for vegetables, children's play equipment, beekeeping equipment, or anywhere you want to avoid copper leaching into soil. Pine tar requires periodic reapplication; PT lumber doesn't. The trade-off is real: pine tar is more work, but it's genuinely non-toxic.

Comparison at a glance

Click to expand

Part 6: How to Apply Pine Tar

What you need

• Pine tar (raw or pre-mixed)
• Raw (purified) linseed oil, if using raw pine tar
• A 70–100mm stiff-bristle brush
• Chemical-resistant gloves
• Safety glasses
• A metal container with a tight-fitting lid and water (for rag disposal — see Safety section)

Click to expand

Mixing

Raw pine tar is too viscous to apply directly and won't penetrate well undiluted. The standard approach: mix 50% pine tar with 50% raw linseed oil by volume. Pre-mixed products (Earth & Flax Pre-Mixed Pine Tar, Auson/Pine Tar World 50/50 blend) skip this step and are ready to apply.

For tool handles, a traditional formula thins it further: 8 parts boiled linseed oil to 1 part pine tar to 1 part turpentine. This produces a more fluid mixture that penetrates dense hardwood handles effectively.

Application

Apply in warm weather: 60°F (15°C) or above. Below that, pine tar thickens and won't flow into the wood properly. Warmer conditions also speed drying. Apply to dry wood only; moisture in the wood blocks penetration and leaves a tacky surface that never fully cures.

Work in thin, even coats with a stiff brush, pushing the mixture into any cracks or crevices. Brush out drips as you go. Runs are harder to fix than to prevent. Per Earth & Flax's application guide, coverage runs approximately 500–600 sq ft per gallon for the 50/50 mix.

Two initial coats, 24 hours apart. Surface dry time is typically 72 hours in good conditions; full cure is one to two weeks. The smell is strong during this period and fades after cure.

First maintenance coat: five years later. After that, every ten years in most temperate climates.

Brands and sourcing

Raw pine tar:

• Auson Genuine Pine Tar 850 (sold through Pine Tar World) — Swedish production, considered the reference standard; available in multiple sizes
• Earth & Flax Authentic Black Pine Tar — US supplier; also offers red pine tar and pre-mixed versions
• George Kirby Jr. Paint Co. — Kirby's Pine Tar — US-made, traditional formulation

Pre-mixed (ready to use):

• Earth & Flax Pre-Mixed Pine Tar (50/50 blend, available in sample and 5-gallon sizes)
• Pine Tar World pre-mixed blend

Where to buy: Direct from Pine Tar World (pinetarworld.com), Earth & Flax (earthandflax.com), or Amazon for Auson products. Some marine supply stores carry it. Big-box hardware stores typically don't stock authentic pine tar — check specialty suppliers first.

Price: Approximately $30–60 per liter for raw pine tar, depending on brand and quantity.

Part 7: Safety

The risk most people don't expect

Rags or cloths soaked in pine tar, especially when mixed with linseed oil, can spontaneously combust. Rapid oxidation generates heat, and a pile of used rags can ignite without any external flame. This is the same risk that plagues linseed oil rags and is responsible for shop fires every year.

Disposal: after use, lay rags flat outdoors to dry, or submerge them in a metal container filled with water. Seal the lid. Never ball up used rags and leave them in a pile indoors.

Click to expand

Other precautions

Skin: Pine tar can cause allergic reactions and skin irritation with prolonged contact. Wear chemical-resistant gloves. Wash hands thoroughly with soap after use. Water alone won't cut through the tar.

Eyes: Causes stinging on contact. Safety glasses during application.

Inhalation: The smell is strong. Work outdoors, or with good air movement if working in a covered structure. High concentrations in a confined space can cause headaches.

Flammability: Per the Pine Tar World Safety Data Sheet for Genuine Pine Tar 850, the flash point is approximately 100°C (212°F), classifying it as a combustible liquid, not a highly flammable one. Turpentine-containing formulas are more volatile (turpentine flash point ~35°C). Keep pine tar away from heat sources, open flame, and strong oxidizers during application and storage.

VOC content: Typically below 300 g/L, well within standard regulatory limits for exterior wood treatments.

Part 8: Where Pine Tar Fits

Pine tar covers the outdoor preservation side of wood finishing, not the indoor side. If you're building furniture, cabinets, or anything that lives inside, your next stop is polyurethane or mineral oil for food-contact surfaces. If you're blending pine tar with linseed oil, the boiled linseed oil guide covers that material in depth: the differences between raw and boiled, dry times, and safe application.

For outdoor structural projects where pine tar shines (fences, garden structures, tool handles), it's one of the most maintenance-friendly treatments available. A gallon of raw pine tar mixed with linseed oil covers 500+ square feet and lasts five years before needing a fresh coat.

Click to expand

Sources

Research on pine tar draws from Scandinavian manufacturer technical documentation, historical naval stores records, and practitioner accounts from woodworking and traditional building communities.

• Pine tar — Wikipedia — composition, production methods, historical overview
• Viking Age tar production and outland exploitation — Antiquity / Cambridge Core — archaeological evidence of Viking Age tar trade
• History of Pine Tar — Packers Pine — Swedish export data and naval stores history
• Naval Stores History — maritime.org — Royal Navy use, historical production and trade
• Application Suggestions for Authentic Pine Tar — Earth & Flax — dilution ratios, coat schedule, coverage, drying times
• Authentic Black Pine Tar — Earth & Flax — product specifications
• Genuine Pine Tar 850 — Pine Tar World — product specs, application guidance
• Safety Data Sheet: Genuine Pine Tar 850 — Pine Tar World — flash point, VOC content, health hazards
• Easy Axe Handle Finishes — Hults Bruk — Swedish axe manufacturer on pine tar for tool handles