Tar and Pitch

Part of Rubber and Polymers

Producing and using tar and pitch as polymer substitutes for waterproofing, adhesion, and sealing when rubber is unavailable.

Why This Matters

Rubber trees do not grow everywhere. If your rebuilding community is in a temperate or cold climate without access to tropical latex or viable temperate alternatives like Russian dandelion, you still need waterproofing, flexible sealants, and adhesives. Tar and pitch — produced by destructive distillation of wood, bark, or coal — fill many of the same roles that rubber and synthetic polymers serve in modern life.

Tar and pitch are among the oldest industrial materials in human history. Vikings waterproofed their longships with pine tar. Ancient Egyptians used bitumen to seal canopic jars and embalm the dead. Neanderthals used birch bark tar as an adhesive over 100,000 years ago. These materials are proven, reliable, and producible with nothing more than fire, wood, and a clay container.

While tar and pitch lack rubber’s elasticity, they excel as waterproof sealants, wood preservatives, adhesives for rigid joints, and protective coatings. In a rebuilding scenario, they are your first line of defense against water damage and material decay until you can establish a rubber supply.

Understanding Tar and Pitch

Definitions

• Tar: A dark, viscous liquid produced by heating organic material (wood, bark, coal) in the absence of air (destructive distillation). Contains hundreds of organic compounds including phenols, cresols, and polycyclic aromatics.
• Pitch: Tar that has been further heated or aged to evaporate its lighter volatile fractions. Pitch is thicker and harder than tar at room temperature, ranging from a thick paste to a brittle solid.
• Resin/Rosin: The natural sap of pine trees, collected without heating. Related to tar but chemically different. Distilling rosin produces similar but cleaner products.

Tar vs Pitch vs Rubber

Property	Tar	Pitch	Rubber
Elasticity	None	None	High
Waterproofing	Excellent	Excellent	Excellent
Temperature sensitivity	Softens in heat	Softens in heat	Stable (if vulcanized)
Adhesion	Good	Very good	Poor (needs solvent)
Wood preservation	Excellent (antiseptic)	Good	Not used for this
Availability	Universal (any wood)	Universal	Limited to specific plants
Flexibility at cold temps	Liquid	Cracks	Remains flexible

Producing Wood Tar

The Pit Method (Simplest)

Used for thousands of years. Requires only a hole, wood, and fire.

1. Dig a pit approximately 60 cm deep and 40 cm wide
2. Dig a small drainage channel from the bottom of the pit to a collection vessel set lower than the pit floor
3. Line the pit with clay to prevent tar from soaking into the soil
4. Fill the pit with chopped wood (pine, birch, or other resinous species are best)
5. Cover the top with turf, clay, or earth, leaving a small opening for ignition
6. Light the wood from the top
7. Seal the opening almost completely — you want smoldering, not open flame
8. Over 8-24 hours, tar drips from the burning wood, runs down through the pit, and collects in the drainage vessel
9. The process is complete when no more liquid flows

Expected yield: 5-15 liters of tar per cubic meter of wood, depending on species and moisture content.

The Retort Method (Higher Quality)

Produces cleaner tar with better control:

1. Build or obtain a sealed vessel (a large clay pot, a metal drum, or a bricked chamber)
2. Fill with chopped wood — do not pack too tightly, gases need to circulate
3. Seal the vessel with a clay lid, leaving one outlet pipe that leads to a collection container
4. Heat the vessel externally with a fire built around it
5. As the wood heats past 300C, it breaks down and releases tar vapor, which condenses in the outlet pipe and collection vessel
6. Continue heating until no more liquid emerges (typically 4-8 hours)
7. The solid residue inside the retort is charcoal — also a useful product

Two products in one

The retort method produces both tar and charcoal simultaneously. This makes it extremely efficient — you get two essential materials from one batch of wood.

Best Wood Species for Tar

Species	Tar Quality	Yield	Notes
Pine (any species)	Excellent — high in phenols	High	The gold standard for wood tar
Birch bark	Excellent — smooth, flexible tar	Moderate	Produces the best adhesive tar
Juniper	Very good	Moderate	Aromatic, insect-repelling
Beech	Good	Moderate	Less aromatic
Oak	Fair	Low	High tannin content
Softwoods generally	Good	High	Resinous woods produce more tar

Producing Birch Bark Tar

Birch bark tar deserves special mention — it was the first adhesive used by early humans and remains one of the most versatile tars available.

Simple Container Method

1. Collect birch bark in large sheets, removing outer white papery layers (the white layers contain more tar precursors)
2. Roll bark tightly and place in a sealed clay container with a small hole in the bottom
3. Invert over a collection vessel buried in the ground
4. Build a fire over the sealed container
5. Tar drips through the hole into the collection vessel
6. Process takes 2-4 hours
7. Yield: approximately 100-200 ml from a bucket-sized container of bark

Properties of Birch Bark Tar

• Stronger adhesive properties than pine tar
• More flexible when cooled — less likely to crack
• Water-resistant once set
• Can be chewed to a workable consistency (historically used as a chewing gum)
• Excellent for hafting stone or metal tools to wooden handles

Converting Tar to Pitch

Pitch is simply tar with its lighter fractions removed, making it thicker and harder.

1. Pour tar into a wide, shallow vessel (to maximize surface area)
2. Heat gently over low flame or coals — do not boil vigorously
3. Stir occasionally as lighter compounds evaporate
4. The tar will gradually thicken
5. Test consistency periodically by dipping a stick and letting it cool:
   • Soft pitch: Drips slowly off the stick when warm, bends when cool
   • Medium pitch: Holds its shape when warm, firm but flexible when cool
   • Hard pitch: Sets rigid when cool, cracks if bent

Fire hazard

Tar and pitch vapors are flammable. Heat slowly over low coals, not direct flame. Have sand or earth ready to smother the vessel if it catches fire. Never heat in an enclosed space.

Mixing Pitch Blends

Pure pitch can be too hard and brittle for many applications. Mix with other materials to adjust properties:

Addition	Effect	Proportion
Beeswax	Increases flexibility	10-20% by weight
Tallow (animal fat)	Softens, improves spreadability	5-15%
Pine rosin	Increases tackiness and adhesion	10-30%
Charcoal powder	Increases thickness, reduces drip	10-20%
Sand or ground stone	Increases abrasion resistance	5-10%
Fiber (chopped grass/hair)	Increases tensile strength	5-10%

Applications

Waterproofing

Boats and containers:

1. Warm pitch until liquid and spreadable
2. Apply with a brush or mop to seams and surfaces
3. For boat hulls, apply hot pitch and immediately press oakum (tarred rope fiber) into seams
4. Apply a second coat of pitch over the oakum
5. This is the traditional “caulking” technique used for wooden ships for millennia

Rope and cordage:

1. Soak rope in warm tar for several hours
2. Hang to dry — the tar penetrates the fiber and creates waterproof, rot-resistant rope
3. “Tarred rope” was standard for all maritime applications

Wood Preservation

Pine tar is a powerful wood preservative, killing fungi and repelling insects:

1. Apply tar to fence posts, structural timbers, and any wood in contact with soil
2. Warm the tar slightly for better penetration
3. A single heavy coat can protect wood for 5-10 years
4. Reapply when the tar coating shows wear

Adhesive

Pitch adhesive for attaching tool heads, sealing joints, and bonding materials:

1. Heat pitch until soft and workable
2. Apply to both surfaces
3. Press together firmly and hold until cooled
4. For tool hafting, wrap the joint with wet rawhide that shrinks tight as it dries
5. The combination of pitch adhesive and rawhide binding creates an extremely strong joint

Torches and Fire Starting

• Dip cloth or tow (fiber bundle) in tar and wrap around a stick for a long-burning torch
• Tar-soaked bark or wood shavings make excellent fire starters in wet conditions
• Pitch can be molded into small fire-starting pellets for emergency kits

Storage and Handling

• Store tar in sealed containers to prevent thickening from evaporation
• Pitch can be stored as solid blocks indefinitely — it does not degrade
• To reuse hardened pitch, heat gently until liquid again
• Clean tools with turpentine, sand, or wood ash (tar is difficult to remove with water alone)
• Pitch on skin can be removed with oil or animal fat, then washed with ash soap

Tar and pitch are the universal polymer substitutes — available wherever trees grow, producible with the simplest technology, and capable of waterproofing, preserving, and bonding almost any material. In the absence of rubber and synthetic plastics, these ancient materials remain remarkably effective solutions.