Petroleum and Tar
Why This Matters
Tar waterproofs boats, preserves wood from rot, lubricates axles, and seals roofs. Petroleum provides lamp oil that burns cleaner and brighter than animal fat, lubricants for machinery, and eventually fuel for engines. These materials bridge the gap between a wood-and-stone society and an industrial one. You can produce wood tar with nothing more than a fire pit and a clay pot; petroleum distillation requires more equipment but unlocks transformative capabilities.
Two Paths: Wood Tar and Petroleum
You have two independent sources for these materials:
- Wood tar — produced by heating wood in a sealed container without air (destructive distillation). Available anywhere trees grow. This is your starting point.
- Natural petroleum — found at surface seeps in certain geological areas. If you have access to it, you can distill it into kerosene, gasoline, lubricants, and asphalt.
Both produce overlapping but distinct products. Start with wood tar — it requires no special geology, just wood and fire.
Wood Tar Production
The Principle: Destructive Distillation
When you heat wood in a sealed container without oxygen, it does not burn. Instead, it breaks down into three products:
- Charcoal (solid residue — you already know this from Charcoal Production)
- Wood tar (thick, dark liquid)
- Wood gas and wood vinegar (gases and watery acid that condense or escape)
A charcoal kiln that captures the liquid runoff is a tar kiln. The only difference is that you collect the liquids instead of discarding them.
Pine Tar (The Most Useful Wood Tar)
Pine and other resinous softwoods produce the most tar because their resin contributes heavily to the liquid yield. Scandinavian shipbuilders produced pine tar by the barrel for centuries.
Step 1 — Collect resinous wood. Pine stumps, roots, and heartwood are richest in resin. Dead pine stumps that have been standing for years are ideal — the sapwood has rotted away, leaving concentrated resinous heartwood called “fatwood.” Split the wood into small pieces (roughly 3-5 cm thick).
Step 2 — Build a tar pit. Dig a shallow, bowl-shaped pit about 1 meter across. Line it with clay to make it liquid-tight. At the lowest point of the bowl, dig a small channel leading to a collection hole outside the pit. Place a clay pot or metal container at the end of the channel to catch the tar.
Step 3 — Stack the wood. Fill the pit with your split pine wood, stacking it tightly. Cover the top of the woodpile with a thick layer of turf, moss, and clay, leaving only a small hole at the top for ignition. The goal is to create a sealed, low-oxygen environment.
Step 4 — Light and control. Ignite the wood through the top hole. Once burning is established, seal the hole partially to restrict airflow. You want the wood to smolder, not blaze. The fire should produce dense white smoke, not flames.
Step 5 — Collect tar. As the wood heats, tar liquefies and flows downhill through the channel into your collection pot. A well-loaded pit of 100 kg of resinous pine will yield roughly 15-25 liters of tar. The process takes 8-24 hours depending on size.
Step 6 — Separate. The collected liquid will separate into two layers: watery wood vinegar (pyroligneous acid) on top and thick dark tar on the bottom. Let it settle in a tall narrow container and drain off the watery layer.
Tip
An alternative to the pit method: use two nested clay pots. Pack the inner pot with pine wood chips and seal it with clay. Invert it over the outer pot and heat the assembly in a fire. Tar drips from the inner pot into the outer pot. This is the “double pot” method, ideal for small batches.
Birch Tar
Birch bark produces a distinctive tar that was used as the first adhesive in human history — Neanderthals glued stone tools to wooden handles with it 200,000 years ago.
Step 1 — Collect birch bark. Peel it from dead trees or fallen logs (do not strip bark from living trees — it kills them).
Step 2 — Roll the bark tightly and pack it into a sealed clay pot. Use the double-pot method described above.
Step 3 — Heat strongly for 2-3 hours. Birch tar is thicker and more adhesive than pine tar. It sets hard when cool and can be re-softened by heating.
Uses: Gluing tool heads to handles, patching small holes in containers, waterproofing stitched seams.
Coal Tar
If you have access to coal and are producing coke (see Charcoal Production), coal tar is a byproduct of the coking process. Coal tar is chemically more complex than wood tar and contains useful compounds.
Collecting Coal Tar
During coal coking, gases and liquids escape from the coal. If you run these through a condenser (a long pipe or coiled tube cooled by water), the vapors condense into:
- Ammoniacal liquor (watery layer — contains ammonia, useful as fertilizer)
- Coal tar (thick, dark, pungent liquid)
Coal Tar Products
| Fraction | Boiling Range | Product | Use |
|---|---|---|---|
| Light oil | 80-170 C | Benzene, toluene | Solvents (handle with extreme care — toxic) |
| Middle oil | 170-230 C | Phenol, naphthalene | Disinfectant, moth repellent |
| Heavy oil | 230-270 C | Creosote | Wood preservative |
| Anthracene oil | 270-350 C | Anthracene | Future dye chemistry |
| Pitch (residue) | Above 350 C | Coal tar pitch | Waterproofing, road surfacing |
Warning
Coal tar contains carcinogenic compounds (benzene, polycyclic aromatic hydrocarbons). Avoid prolonged skin contact and never inhale the fumes in an enclosed space. Always work outdoors or with strong ventilation. Wash hands thoroughly after handling.
Creosote for Wood Preservation
Creosote is the fraction of coal tar that boils between 230-270 C. It is the most effective wood preservative known — railroad ties, telephone poles, and fence posts were treated with creosote for over a century.
Step 1 — Distill coal tar by heating it gently in a retort (a sealed pot with an outlet tube leading to a condenser). Discard the first fractions (light oil — dangerous). Collect the fraction that comes over between 230-270 C. This is your creosote.
Step 2 — Apply creosote to wood by brushing or soaking. For maximum penetration, heat the wood first (hot wood absorbs liquid more deeply as it cools and the air inside contracts).
Step 3 — Treated wood resists rot, insects, and fungal decay for decades. Use it for posts, pilings, and any wood in contact with soil or water.
Natural Petroleum
Finding Petroleum Seeps
Petroleum sometimes reaches the Earth’s surface naturally. Signs include:
- Oil slicks on water — rainbow-colored film on still ponds, streams, or springs
- Tar pits — pools of thick, sticky black material (bitumen/asphalt)
- Gas bubbles — natural gas escaping through water or soft ground
- Sulfur smell — petroleum often contains hydrogen sulfide, which smells like rotten eggs
- Black or dark-stained rock — sandstone or shale saturated with oil
- Lack of vegetation — petroleum-contaminated soil kills plants, creating bare patches
Tip
Petroleum seeps have been known and used for thousands of years. Ancient Mesopotamians used bitumen from the Dead Sea and Iraqi seeps to waterproof boats, seal buildings, and pave roads. If you find a seep, you have a resource that civilizations fought wars over.
Collecting Crude Oil
From surface seeps: Dig a shallow pit near the seep to collect oil. Line it with clay. Oil will slowly accumulate. Skim it off the surface of any collected water using a flat board or absorbent cloth (wool works well — it absorbs oil but not water; wring it out into a container).
From shallow wells: If oil is seeping from rock, dig down to the oil-bearing layer. Line the shaft with stone or wood to prevent collapse. Oil will accumulate in the bottom. Bail it out with a bucket.
Petroleum Distillation
Crude petroleum is a mixture of hundreds of compounds with different boiling points. By heating crude oil and collecting the vapors at different temperatures, you separate it into useful fractions.
Equipment Needed
- A metal or ceramic retort (sealed pot with an outlet tube at the top)
- A condenser (a long pipe or coiled copper tube that passes through a cooling vessel filled with water)
- Collection containers for different fractions
- A thermometer if available, or careful observation of vapor behavior
The Distillation Process
Step 1 — Pour crude oil into the retort, filling it no more than half full. Seal the retort, ensuring the outlet tube is connected to the condenser.
Step 2 — Heat the retort slowly and evenly. Use a wood fire that you can control.
Step 3 — Collect fractions by temperature:
| Fraction | Temperature Range | Appearance | Primary Use |
|---|---|---|---|
| Naphtha/gasoline | 40-150 C | Clear, water-thin, very volatile | Fuel (internal combustion), solvent, cleaning |
| Kerosene | 150-275 C | Clear to pale yellow, oily | Lamp oil, heating fuel |
| Diesel/gas oil | 275-350 C | Yellow to brown, heavier | Engine fuel (future), heating |
| Residue | Above 350 C | Black, thick | Asphalt, lubricant base, pitch |
Step 4 — Without a thermometer, use these visual cues:
- First vapors at low heat are gasoline — extremely volatile, almost invisible, with a sharp smell. Collect carefully in a sealed metal container.
- As temperature rises, the condensed liquid becomes slightly yellow and oily — this is kerosene. The most useful fraction for lamps.
- At higher temperatures, the liquid becomes darker and thicker. This is the heavy fraction.
- What remains in the retort after all distillation is asphalt/bitumen — a thick, black, semi-solid.
Warning
Gasoline vapors are extremely flammable and explosive when mixed with air. NEVER distill petroleum near open flames other than the heat source under the retort. The condenser outlet must be at least 3 meters from any flame. Work outdoors. Have sand or earth available to smother fires — water does not extinguish petroleum fires effectively.
Pitch: The Universal Sealant
Pitch is tar reduced (boiled down) to a thick, semi-solid consistency. It has been used for waterproofing for at least 40,000 years.
Making Pitch from Tar
Step 1 — Pour wood tar into a wide, open pot (not sealed — you want vapors to escape).
Step 2 — Heat gently over a low fire. The volatile components will evaporate, leaving increasingly thick residue. Stir regularly.
Step 3 — Continue until the tar reaches the consistency of thick honey when hot. When a drop placed on a cool surface solidifies within a minute and can be snapped like hard candy, the pitch is ready.
Step 4 — Pour into molds or storage containers. Pitch is solid at room temperature and liquid when heated. It can be remelted and reused indefinitely.
Pitch Applications
| Application | Method | Notes |
|---|---|---|
| Boat caulking | Heat pitch, press into seams between planks with a caulking iron | Mix with oakum (shredded rope fiber) for gap-filling |
| Rope preservation | Dip rope in hot pitch, hang to drip-dry | ”Tarred rope” resists rot from water |
| Roof sealing | Brush hot pitch onto flat roof surfaces, press fabric into it | Layer: pitch, fabric, pitch for best waterproofing |
| Container sealing | Swirl hot pitch inside clay pots to coat interior | Makes porous pottery water-tight |
| Torch making | Wrap cloth around stick, soak in pitch | Burns steadily for hours |
Lubricants
Moving parts need lubrication. Without it, axles seize, bearings overheat, and machinery fails.
Tar-Based Axle Grease
Step 1 — Mix wood tar with animal fat (tallow) in a ratio of roughly 1:1. Heat gently and stir until blended.
Step 2 — Add fine powdered charcoal or graphite if available (about 10 percent by volume). This adds solid lubrication.
Step 3 — Let cool to a paste consistency. Apply to wooden axles, hinges, and any sliding or rotating joint.
Petroleum-Based Lubricant
The heavy residue from petroleum distillation (above 350 C) is a natural lubricant. It is slippery, stays in place, and does not dry out quickly. Apply it directly to metal-on-metal contact surfaces.
Asphalt and Road Surfacing
The heaviest fraction of petroleum distillation — or the residue from pitch-making — is asphalt (bitumen). Mixed with gravel, it produces a waterproof, durable road surface.
Step 1 — Heat asphalt/bitumen until it flows freely.
Step 2 — Mix with graded gravel and sand: roughly 5-8 percent asphalt by weight, the rest aggregate. Mix while hot.
Step 3 — Spread the mixture over a prepared road base (compacted gravel). Level it and compact it by rolling or tamping while still warm.
Step 4 — The surface hardens as it cools. It sheds water, resists rutting, and provides a smooth travel surface. This is essentially how modern asphalt roads are still made.
Safety Protocols
| Hazard | Risk Level | Prevention |
|---|---|---|
| Gasoline vapors | CRITICAL | No open flames within 3 meters of collection point; work outdoors only |
| Tar burns | HIGH | Hot tar sticks to skin and continues burning; wear thick leather gloves; keep cold water nearby |
| Carbon monoxide | HIGH | Destructive distillation produces CO; never operate tar kilns in enclosed spaces |
| Petroleum fire | HIGH | Sand or earth to smother; NEVER use water on petroleum fires |
| Coal tar toxicity | MODERATE | Avoid prolonged skin contact; do not inhale fumes; wash hands after handling |
| Storage | MODERATE | Use metal or ceramic containers only; label clearly; store away from living areas and heat sources |
| Spontaneous ignition | MODERATE | Oil-soaked rags can self-ignite; hang to dry or submerge in water |
Warning
Water does NOT extinguish petroleum fires. It spreads them. Burning petroleum floats on water and the fire expands. Always use sand, dry earth, or a heavy blanket to smother petroleum and tar fires.
What’s Next
With tar, pitch, and petroleum products, you are ready for:
- Internal Combustion — use distilled gasoline and kerosene to power engines
- Roads and Transport — build durable asphalt-surfaced roads
Petroleum and Tar -- At a Glance
Wood Tar (Available Anywhere):
- Heat resinous wood (pine) in sealed container without air
- Liquid tar flows out, charcoal remains
- 100 kg pine wood yields 15-25 liters of tar
Key Products:
Product Source Primary Use Pine tar Destructive distillation of pine Rope treatment, wood preservation Birch tar Destructive distillation of birch bark Adhesive, waterproofing Pitch Tar reduced by boiling Boat caulking, roof sealing Creosote Coal tar, 230-270 C fraction Wood preservation Kerosene Petroleum, 150-275 C fraction Lamp oil Gasoline Petroleum, 40-150 C fraction Engine fuel, solvent Asphalt Petroleum residue above 350 C Road surfacing Critical Safety Rules:
- Never distill petroleum near open flames (except heat source)
- Smother petroleum fires with sand — NEVER water
- Work outdoors — tar and petroleum fumes are toxic
- Hot tar causes severe burns — wear leather gloves
- Store in metal/ceramic only — never wood or cloth containers