Pitch Making

Part of Adhesives

Producing pitch from tree resin and wood tar for waterproofing, bonding, and sealing applications.

Why This Matters

Pitch is one of humanity’s oldest manufactured materials — a thick, black, waterproof substance produced by heating tree resin or distilling wood. Before the petroleum age, pitch was essential for shipbuilding, roofing, road construction, and waterproofing. The phrase “pitch black” comes from this substance. Entire economies revolved around its production; the Baltic states exported thousands of tons annually for centuries.

For a rebuilding community, pitch solves the fundamental problem of keeping water out. Every boat, every roof, every water container, every underground structure needs waterproofing. Pitch provides this using only trees and fire. It bonds to wood, fiber, leather, and masonry. It fills gaps, seals seams, and protects surfaces from rot and decay.

There are two distinct production methods — resin-based pitch (heating and concentrating tree resin) and wood tar pitch (destructive distillation of wood). Both produce usable waterproofing and adhesive, but their properties differ. Understanding both methods gives a community flexibility based on available resources.

Resin-Based Pitch

The simpler of the two methods. Tree resin is collected, heated to drive off volatile turpentine, and cooked until it reaches the desired consistency.

Process

1. Collect resin — pine, spruce, or fir resin in quantity. You need roughly 2 kg of raw resin to produce 1 kg of pitch (the rest evaporates as turpentine)
2. Prepare the cookfire — use a bed of hot coals, not open flame. Resin vapors are extremely flammable
3. Melt resin in a metal pot — a wide, shallow pot works best for even heating. Start with low heat
4. Skim debris — bark, needles, and insects float to the surface as resin liquefies. Remove with a slotted spoon or stick
5. Increase heat gradually — the resin bubbles as turpentine evaporates. This stage smells strongly of pine
6. Monitor consistency — as turpentine cooks off, the resin darkens from golden to amber to brown
7. Test regularly — dip a stick, let it cool 30 seconds. When the cooled drop is firm and slightly flexible (like thick toffee), pitch is ready
8. Pour into molds — bark trays, clay forms, or directly onto tools for storage

Critical Safety

Turpentine vapor is explosive in concentration. NEVER seal the cooking vessel. ALWAYS work outdoors with wind at your back. Keep a lid or wet cloth ready to smother flames if the pot catches fire. NEVER add water to burning pitch — it will splatter.

Timing and Temperature

Stage	Temperature	Time	Visual Indicator
Melting	60-80°C	10-15 min	Resin liquefies, golden
Turpentine off	100-150°C	20-40 min	Vigorous bubbling, strong smell
Pitch forming	150-200°C	10-20 min	Bubbling slows, color darkens
Done	Remove from heat	—	Dark brown/black, thick

Do not overheat. If pitch turns completely black and smokes without bubbling, it has been overcooked and will be brittle when cool. Slightly underdone is better than overdone — you can always reheat.

Wood Tar Pitch

Wood tar is produced by destructive distillation — heating wood in an oxygen-limited environment so it breaks down into tar, charcoal, and gases rather than burning. The tar is then further cooked into pitch.

The Pit Method

The simplest distillation setup, used for thousands of years:

1. Dig two pits — an upper pit (fire chamber, 60-80 cm deep) and a lower collection pit (30 cm deep), connected by a sloped channel
2. Line the collection pit with clay or place a container at the lowest point
3. Fill the upper pit with resinous wood — pine stumps, fatwood, bark, and branches, split into small pieces
4. Cover the wood with a thick layer of turf, clay, or damp earth, leaving a small opening at the top for ignition and air control
5. Light from the top and immediately restrict airflow by partially sealing the opening
6. Maintain slow burn for 6-12 hours — smoke should be thick and white/yellow, not clear. Clear smoke means too much air
7. Tar drips down through the channel into the collection pit as the wood pyrolyzes
8. Collect tar from the lower pit after the burn is complete and everything has cooled

A well-managed pit burn of 100 kg of resinous pine wood yields approximately 10-15 kg of tar.

The Retort Method

More efficient but requires a metal or ceramic vessel:

1. Pack a sealed metal container (old barrel, large pot with lid) with wood chips and resinous wood
2. Drill a small hole in the bottom or side for tar to drain out
3. Place over a fire with the drain hole positioned over a collection vessel
4. Heat strongly for 4-8 hours
5. Tar drips out through the hole as wood pyrolyzes inside the sealed container
6. Charcoal remains inside the retort — useful as fuel and as an adhesive filler

Converting Tar to Pitch

Raw wood tar is too fluid for most adhesive applications. It must be concentrated:

1. Pour tar into a wide, shallow pan to maximize surface area
2. Heat gently — the volatile components (wood spirits, light oils) evaporate first
3. Stir occasionally to prevent skin formation on the surface
4. Test frequently — when a cooled drop holds its shape and is firm to the touch, pitch is ready
5. Reduce by roughly 50% — half the original tar volume becomes pitch

Pitch Properties

Property	Resin Pitch	Wood Tar Pitch
Color	Dark brown	Black
Flexibility	More flexible	Stiffer
Waterproofing	Excellent	Excellent
Adhesion to wood	Very good	Excellent
Smell	Pine scent	Smoky, tarry
Toxicity	Low	Moderate (contains creosote)
Availability	Requires living trees	Can use dead wood, stumps

Applications

Boat and Ship Caulking

The most historically significant use of pitch:

1. Drive oakum (tarred rope fiber) into seams between planks using a caulking iron and mallet
2. Heat pitch until flowing freely
3. Pour or brush hot pitch over the caulked seams, filling completely
4. Build up layers — two or three applications for below-waterline seams
5. Coat the entire hull with a thin layer of hot pitch for protection against marine organisms

Roofing

Pitch waterproofs thatched, shingled, and flat roofs:

• Thatch: brush diluted pitch (thinned with turpentine or oil) onto exposed thatch surfaces
• Shingles: dip the bottom 2/3 of each shingle in hot pitch before installation
• Flat roofs: layer fabric and pitch alternately — apply hot pitch, lay cloth, apply more pitch, repeat for 3-5 layers (this is the origin of “tar paper”)

Wood Preservation

Pitch protects wood from rot, insects, and moisture:

• Fence posts, foundation timbers, and any wood in ground contact should be coated with hot pitch before installation
• Apply while the wood is warm (sun-heated or fire-warmed) so pitch penetrates deeper into the grain
• Posts treated with pitch last 3-5 times longer than untreated wood in ground contact

Container Sealing

• Coat the inside of wooden barrels and buckets with thin, hot pitch to make them watertight
• Seal woven baskets for liquid storage
• Waterproof leather bags and skins

Modifying Pitch Properties

Additive	Effect	Typical Amount
Beeswax	Increases flexibility, lowers melting point	10-20%
Tallow/fat	Softens pitch, improves cold-weather flexibility	5-15%
Charcoal powder	Thickens, adds body, improves adhesion	10-30%
Sand or powdered lime	Extends volume, increases hardness	Up to 50%
Turpentine/oil	Thins for brushing, improves penetration	As needed
Plant fibers	Reinforces, prevents cracking	5-10%

Storage

Pitch stores indefinitely at room temperature. It neither rots nor evaporates. Store as:

• Solid blocks — pour into molds and stack when cool
• Pitch sticks — wrap around sticks for portable field use
• In bark containers — traditional method; bark doesn’t stick to pitch

To reuse, simply reheat. Pitch can be remelted dozens of times without significant degradation, though it gradually becomes more brittle with each heating cycle as remaining volatiles escape.

Pitch making is a foundational skill for any community near forests. Whether sealing a boat, roofing a building, or preserving timbers, this ancient material provides waterproofing and protection that no other natural substance matches in durability and ease of production.