Pitch and Waterproofing

Part of Petroleum and Tar

Using pitch — refined tar — as a comprehensive waterproofing material for boats, buildings, and containers.

Why This Matters

Water is the primary destroyer of human-made structures. It rots wood, dissolves mortar, corrodes metal, undermines foundations, and ruins stored goods. Effective waterproofing is the difference between structures that last decades and those that fail within years. In a rebuilding society, pitch — the refined, concentrated form of tar — is your most versatile and accessible waterproofing material.

Pitch has been humanity’s primary waterproofing agent for at least 8,000 years. The Bible describes Noah waterproofing the Ark with pitch. The Mesopotamians coated their reed boats with bituminous pitch. The Norse waterproofed their longships with pine pitch. The technology is ancient, proven, and requires no materials beyond what is available from forests or petroleum seeps.

The value of reliable waterproofing extends far beyond keeping rain out. Waterproofed containers can store water, grain, and other goods safely. Waterproofed boats enable fishing, trade, and exploration. Waterproofed foundations protect the investment of labor in every building. Mastering pitch application is one of the highest-return skills a rebuilding community can develop.

Types of Pitch and Their Properties

Different pitch sources produce materials with different characteristics:

Pitch Type	Source	Flexibility	Water Resistance	Best For
Pine pitch	Cooked pine tar	Good	Excellent	Boats, ropes, wood treatment
Birch pitch	Birch bark pyrolysis	Very good	Excellent	Adhesive, small vessels, leather
Petroleum pitch	Heavy petroleum residue	Variable	Excellent	Roads, foundations, large surfaces
Coal tar pitch	Coal distillation	Moderate	Excellent	Industrial waterproofing

Pine Pitch

Made by cooking pine tar until light volatiles evaporate (see Pitch Making). The standard maritime waterproofing material. Remains somewhat flexible at moderate temperatures, adheres well to wood, and is naturally antiseptic.

Birch Pitch

Produced by pyrolysis of birch bark. This is the oldest known adhesive — Neanderthals used birch pitch 200,000 years ago. It has excellent adhesive properties and flexibility, but birch bark is less abundant than pine resin in many regions.

Petroleum Pitch

The heavy residue from petroleum distillation. Harder and more brittle than pine pitch at low temperatures, but exceptionally water-resistant. Best for static applications (foundations, cisterns) where flexibility is less important.

Waterproofing Boats and Watercraft

Marine waterproofing is the most demanding application for pitch — the material must resist constant immersion, flex with hull movement, and withstand impact and abrasion.

Hull Planking

1. Prepare the surface: Scrape or sand the wood to bare grain. Remove all old pitch, paint, dirt, and loose material. The wood should be clean and dry.

2. Apply primer coat: Thin pitch with turpentine or light oil (about 70% pitch, 30% thinner). Brush this thin mixture onto the entire hull surface and let it soak in for 24 hours. This penetrates the wood grain and provides a base for subsequent coats.

3. Apply hot pitch: Heat pitch until it flows like thick syrup (approximately 100-120°C). Using a long-handled brush or mop, apply hot pitch to the hull in even strokes, working from keel to waterline.

4. Second coat: After the first coat cools and hardens (at least 12 hours), apply a second coat of hot pitch. Two coats is the minimum for any hull below the waterline.

5. Third coat for heavy service: Boats in constant use or in salt water benefit from a third coat. Allow each coat to cool fully before the next.

Seam Caulking

Gaps between hull planks must be sealed before pitch application:

1. Prepare oakum: Untwist old rope or use raw hemp/cotton fiber. Roll it into loose, even strands.
2. Drive oakum into seams: Use a caulking iron (a flat-bladed chisel) and mallet to press oakum tightly into every seam. Work from one end to the other, making two passes — a light packing first, then a firm driving pass.
3. Hot-pour pitch: Fill the seam over the oakum with hot pitch. The pitch should be thin enough to flow into the seam but thick enough to not run out.
4. Smooth and fair: While still warm, smooth the pitch flush with the hull surface using a heated iron or paddle.

Above-Waterline Treatment

The hull above the waterline needs protection from sun, rain, and spray but is not immersed. A single coat of thinned pitch or a mixture of pitch and linseed oil provides adequate protection with easier maintenance.

Seasonal Maintenance

Haul boats out annually and inspect the pitch coating. Scrape off loose or cracked pitch, reprep the exposed wood, and apply fresh pitch. Seams that have opened should be re-caulked. Annual maintenance extends hull life indefinitely.

Waterproofing Buildings

Foundation and Below-Grade Walls

The most critical waterproofing application for buildings. Moisture wicking up from the ground (rising damp) destroys walls, promotes mold, and makes buildings uninhabitable.

1. Apply to exterior foundation walls before backfilling. Heat pitch and brush on in two coats.
2. Create a damp-proof course: At the base of above-ground walls, embed a layer of fabric (burlap, canvas) saturated with pitch between courses of stone or brick. This breaks the capillary path for rising moisture.
3. Drainage: Pitch alone is not enough — ensure water drains away from foundations. But pitch prevents the moisture that does reach the foundation from penetrating.

Cisterns and Water Storage

1. Build the cistern from stone, brick, or concrete
2. Allow masonry to cure fully (at least 2 weeks for lime mortar)
3. Apply pitch to the interior in thin, even coats — at least 3 coats for drinking water storage
4. Allow each coat to cool completely before the next
5. Curing period: After final coat, fill with water and let stand for 2-4 weeks, changing the water weekly. This leaches out soluble compounds
6. Flush a final time before putting into drinking water service

Containers and Barrels

Pitch-lined vessels can hold water, wine, beer, oil, and other liquids:

1. Heat the barrel or container slightly to warm the wood
2. Pour hot pitch inside and rotate the container to coat all interior surfaces
3. Pour out excess
4. Let cool in the desired orientation (upright for barrels)
5. For barrels, coat the interior of both heads separately before assembly
6. Seams can be reinforced with a line of hot pitch applied with a narrow brush

Waterproofing Fabric and Leather

Canvas Waterproofing

Create waterproof tarps, tent material, and rain gear:

1. Mix pitch with linseed oil or animal fat (50:50) and warm until thin enough to brush
2. Stretch fabric flat on a frame or clean surface
3. Brush the warm mixture onto one side, working it into the weave
4. Let dry for 48 hours
5. The result is heavy, stiff, and completely waterproof — hence “tarpaulin” (tar + palling, a cloth covering)

Leather Waterproofing

A lighter touch is needed for leather to preserve flexibility:

1. Mix pitch with 3 parts beeswax and 2 parts tallow or lard
2. Warm until liquid and well-blended
3. Apply to leather with a cloth, working into the surface
4. Allow to absorb, then buff with a dry cloth
5. This produces a water-resistant (not fully waterproof) surface that remains supple

Modifying Pitch Properties

Increasing Flexibility

Pure pitch becomes brittle in cold weather. For applications requiring flexibility:

• Add 10-20% animal fat (tallow) or fish oil
• Mix in 10-15% beeswax
• Blend with raw (uncooked) tar — retaining some volatile components

Increasing Hardness

For applications where rigidity is desired (flooring, road surfaces):

• Cook the pitch longer to drive off more volatiles
• Add 5-10% sulfur (melt sulfur into the hot pitch) for a harder, more chemical-resistant product
• Mix with sand or powite mineral filler (3:1 filler to pitch)

Adhesive Pitch

For bonding applications:

• Birch pitch is naturally superior as an adhesive
• Add finely powdered charcoal (10-20% by weight) to pine pitch to improve adhesive properties
• Add beeswax (5-10%) for a more workable, re-heatable adhesive

Application Best Practices

Temperature Control

Pitch performance depends on application temperature:

• Too cold: Pitch is thick and does not flow into pores or gaps. Poor adhesion.
• Optimal (100-130°C for pine pitch): Flows well, penetrates wood grain, forms smooth coatings.
• Too hot (above 180°C): Pitch smokes, thins excessively, and may ignite. Thinner coatings that provide less protection.

Surface Preparation

Pitch adheres poorly to:

• Wet or damp surfaces — always apply to dry material
• Dirty or oily surfaces — clean thoroughly before application
• Very smooth surfaces — rough up glass-smooth surfaces with sandstone for better grip
• Previously painted surfaces — strip old finishes first

Quantity Estimates

Application	Pitch Needed per m²	Coats
Hull below waterline	1.0-1.5 liters	2-3
Hull above waterline	0.5-0.8 liters	1-2
Foundation walls	0.8-1.2 liters	2
Cistern interior	0.6-1.0 liters	3
Fabric waterproofing	0.5-0.8 liters (blended)	1

Working Safely

Hot pitch causes severe burns that are worsened by the material sticking to skin. Wear heavy gloves, long sleeves, and eye protection. If hot pitch contacts skin, cool immediately with water — do not attempt to peel off until fully cooled. Keep sand nearby to smother any pitch fires. Never heat pitch over open flame; use indirect heat or a water bath for small quantities.