Waterproof Fabric

Part of Rubber and Polymers

Creating waterproof fabric using rubber coatings, wax treatments, and oil-based methods for clothing, shelters, and equipment.

Why This Matters

Staying dry is a survival priority. Wet clothing causes hypothermia. Wet equipment rusts. Wet food stores rot. Wet bedding means no sleep. A rebuilding community needs reliable waterproof fabric for raincoats, tarps, tent roofing, bags for transporting goods in rain, covers for stored food and tools, and medical applications where sterile dry barriers matter.

Before synthetic waterproof membranes like Gore-Tex, people used rubber-coated fabric, oiled cloth, and waxed canvas to stay dry. These methods work. They are not as breathable or lightweight as modern materials, but they are absolutely effective at keeping water out. More importantly, they can be made entirely from locally available materials.

Waterproof fabric is also one of the most efficient uses of your rubber supply. A thin rubber coating — mere grams per square meter — transforms ordinary cloth into a waterproof barrier. Compared to making solid rubber products, waterproofing fabric stretches your rubber supply enormously.

Rubber-Coated Fabric (Mackintosh Method)

The most effective method, producing truly waterproof fabric.

Materials

• Tightly woven fabric (cotton canvas, linen, or tightly woven wool)
• Rubber solution (rubber dissolved in turpentine, 1 part rubber to 3-4 parts turpentine)
• Brush or cloth applicator
• Flat surface for stretching fabric
• Chalk or talc for finishing

Process

1. Prepare the fabric: Wash thoroughly to remove oils, sizing, and dirt. Natural oils in unwashed fabric prevent rubber from adhering. Dry completely.

2. Stretch taut: Pin or tack the fabric to a smooth board or frame, pulling out all wrinkles. Wrinkles trap rubber solution and create thick spots that crack.

3. Apply first coat:

   • Dip your brush in rubber solution
   • Apply in long, even strokes in one direction
   • Cover the entire surface without leaving gaps or puddles
   • Work quickly — the turpentine begins evaporating immediately

4. Dry completely: Allow 4-12 hours in a ventilated area (outdoors is best due to turpentine fumes). The surface should feel dry and slightly tacky.

5. Apply second coat: Brush perpendicular to the first coat. This cross-hatching ensures no thin spots aligned with the weave.

6. Repeat: Apply 3-5 total coats, alternating brush direction, drying fully between each coat.

7. Finishing: Dust the final dried coat with chalk, talc, or fine cornstarch to eliminate surface tackiness.

Double-Texture Construction

For maximum durability and waterproofing (the original Macintosh raincoat method):

1. Coat the inside surface of one fabric piece with rubber solution
2. While the coating is still tacky (10-20 minutes after application), press a second piece of fabric onto the coated surface
3. Roll firmly with a smooth cylinder from center to edges, pressing out air bubbles
4. The result is a sandwich: fabric / rubber layer / fabric
5. The rubber is protected from UV and abrasion by fabric on both sides
6. This construction lasts 3-5 times longer than single-sided coating

Seam Treatment

Waterproof fabric is only as good as its seams:

1. Overlap seams by at least 2 cm (do not use butt joints)
2. Apply rubber solution along the seam line before stitching
3. After stitching, apply a generous coat of rubber solution over the stitch line on both sides
4. Press a 2 cm wide strip of rubber-coated fabric over each seam while the solution is tacky
5. This tape-over-seam technique prevents water wicking through needle holes

Oiled Fabric (Oilskin)

An older method that predates rubber waterproofing. Less effective than rubber but uses more readily available materials.

Linseed Oil Method (Best)

Linseed oil polymerizes (hardens) when exposed to air, creating a flexible waterproof film.

1. Prepare fabric: Use tightly woven cotton or linen. Wash and dry.
2. Heat the oil: Warm linseed oil gently (do not boil) to improve penetration.
3. Apply: Brush warm oil onto the fabric, ensuring complete saturation.
4. Hang to cure: Hang in a warm, well-ventilated area for 2-3 weeks. The oil slowly oxidizes and hardens.
5. Apply second coat: Once the first coat is no longer sticky, apply a second coat.
6. Final cure: Allow another 2-3 weeks of curing.

Spontaneous combustion risk

Linseed oil-soaked rags can self-ignite through oxidation heat buildup. Always hang oiled fabric to dry spread flat — never crumple oil-soaked materials into a pile. Dispose of application rags by submerging in water or spreading flat to dry.

Other Oil Options

Oil	Waterproofing Quality	Drying/Curing	Availability
Linseed	Excellent	Cures hard in 2-3 weeks	Flax seed pressing
Tung oil	Excellent	Cures faster than linseed	Tung tree nuts (tropical)
Walnut oil	Good	Cures slowly (3-4 weeks)	Walnut pressing
Fish oil	Fair	Partially cures, remains slightly oily	Fish liver rendering
Animal fat (tallow)	Fair	Does not fully cure — remains greasy	Rendering

Waxed Fabric (Waxed Canvas)

Wax waterproofing creates a water-repellent (not fully waterproof) fabric that breathes better than rubber-coated material.

Beeswax Method

1. Melt beeswax in a double boiler (a pot inside a pot of water) — never melt wax over direct flame
2. Optionally add a small amount of linseed oil (1 part oil to 4 parts wax) for flexibility
3. Lay fabric flat on a surface that can handle wax drips
4. Apply melted wax with a brush, working it into the fabric weave
5. Use a warm iron (a heated flat stone or metal plate) to help the wax penetrate deeper
6. Apply evenly — hold the fabric up to light to check for missed spots (they appear lighter)
7. Allow to cool and set

Paraffin Method

If you have access to paraffin wax (from petroleum deposits or coal tar distillation):

1. Dissolve paraffin in turpentine (1 part paraffin to 2 parts turpentine by weight)
2. Brush the solution onto fabric
3. The turpentine evaporates, leaving a thin paraffin coating
4. This is faster and more even than the hot-wax method
5. Repeat for additional water resistance

Re-Waxing

Waxed fabric loses its water repellency over time, especially in areas of high wear and flex:

1. Brush or rub additional wax into worn areas
2. Use a warm iron to melt the wax into the fabric
3. Re-wax every 6-12 months for active-use garments

Comparing Methods

Property	Rubber Coated	Oiled (Linseed)	Waxed
Waterproofness	Excellent — fully waterproof	Very good	Good — water repellent
Breathability	None	Very low	Moderate
Flexibility	Good	Good	Fair (stiffens in cold)
Durability	1-3 years	1-2 years	6-12 months between re-waxing
Weight added	Light	Moderate	Moderate
Material cost	Requires rubber	Requires drying oil	Requires wax
Odor	Turpentine (fades)	Linseed oil smell	Neutral
Fire resistance	Poor	Poor	Poor

Product Patterns

Raincoat

1. Cut fabric to pattern: front panels, back panel, sleeves, hood
2. Waterproof all pieces before assembly (easier to coat flat pieces)
3. Stitch with waxed thread and overlap seams facing downward (so rain runs over, not into, the seam)
4. Seal all seams with rubber solution and tape
5. Add a flap behind any button or fastener line

Tarp/Groundsheet

1. Cut fabric to desired size plus 5 cm border for hemming
2. Hem all edges (double fold) to prevent fraying
3. Waterproof after hemming
4. Add grommets or tie-out loops at corners and edges:
   • Fold a small pebble into the corner of the fabric
   • Tie cordage around the pebble — this creates a secure attachment point without metal grommets

Bags and Pouches

1. Cut two identical panels
2. Waterproof the outer surfaces
3. Stitch together inside-out, then turn right-side-out
4. Seal all seams from the outside with rubber solution
5. Add a fold-over closure at the top (rolling the opening down several times creates a watertight seal)

Maintenance and Repair

Cleaning Waterproof Fabric

• Wipe with a damp cloth — do not submerge in soapy water (soap degrades rubber coatings)
• Do not wring or twist — this cracks the coating
• Dry flat or hanging in shade — never near a fire or in direct sun

Repairing Damage

1. Clean the area around the damage
2. Cut a patch from waterproofed fabric, 2-3 cm larger than the damage
3. Apply rubber solution to both the patch and the damaged area
4. Wait until tacky (10-20 minutes)
5. Press the patch firmly in place
6. Apply a second coat of rubber solution over the patch edges
7. Let cure for 24 hours before use

Storage

• Store loosely rolled (not folded — folds create permanent creases that crack the coating)
• Keep in a cool, dark, dry place
• Dust with talc if storing rubber-coated fabric to prevent self-adhesion
• Hang if possible to prevent pressure creases

Waterproof fabric is one of the most impactful products you can make for your community. A single afternoon of coating transforms ordinary cloth into rain gear, equipment covers, and water barriers that protect against one of nature’s most persistent threats.