Alternative Polymers

Part of Rubber and Polymers

Non-rubber natural polymers available for gaskets, coatings, adhesives, and moldable materials.

Why This Matters

Rubber trees grow only in tropical climates, and even alternative latex sources like dandelions require specific growing conditions and labor-intensive harvesting. A rebuilding civilization in temperate or arid regions needs polymer substitutes that can be sourced locally. Fortunately, nature provides a remarkable variety of materials with polymer-like properties — from animal proteins and plant gums to shellac and cellulose derivatives.

These alternative polymers filled essential roles for thousands of years before synthetic plastics existed. Casein from milk was molded into buttons, combs, and knife handles. Shellac coated everything from electrical insulation to furniture. Hide glue bonded wood joints that have held for centuries. Cellulose from plant fibers was processed into films and coatings. Understanding these materials gives a community the ability to produce flexible, moldable, waterproof, and adhesive substances without any rubber at all.

The key insight is that polymers are everywhere in biology — every protein, every cellulose fiber, every strand of chitin in an insect shell is a polymer. The challenge is not finding polymers but learning to process and shape them into useful forms. This article surveys the major categories and their practical applications.

Protein-Based Polymers

Proteins are natural polymers made from amino acid chains. Several protein sources can be processed into useful materials:

Casein (Milk Protein)

The most versatile protein polymer. When milk is curdled with acid, the casein precipitates as a solid that can be dried, molded, and hardened:

• Source: Any mammalian milk — cow, goat, sheep
• Properties: Hard when dry, can be molded when warm and wet, takes dyes well
• Applications: Buttons, beads, small containers, adhesives, paint binder
• Hardening: Immersion in formaldehyde solution makes casein waterproof and extremely hard
• Limitations: Brittle without hardening treatment, absorbs moisture

See Also

Detailed casein extraction and molding procedures are covered in Casein Extraction and Casein Plastic.

Gelatin (Collagen)

Derived from animal hides, bones, and connective tissue by prolonged boiling:

• Source: Cattle hides, pig skin, fish bones and skin, antlers
• Properties: Dissolves in hot water, gels when cool, forms flexible films
• Applications: Adhesive (hide glue), photographic film, capsules for medicines, sizing for paper and textiles
• Processing: Simmer bones/hides in water for 12-24 hours, strain, concentrate by gentle boiling, pour into molds or dry into sheets

Gelatin Source	Quality	Notes
Cattle hide	Highest	Strongest adhesive, clearest films
Rabbit skin	High	Traditional artists’ sizing
Fish swim bladders	Very high	Isinglass — finest grade, used for clarification
Bones	Medium	Must be degreased first
Hooves	Lower	Darker color, weaker bond

Keratin (Hair and Horn)

The protein in hair, wool, feathers, hooves, horns, and tortoiseshell:

• Source: Universally available from livestock
• Properties: Becomes plastic when heated in boiling water or steam, hardens when cool
• Applications: Combs, buttons, cups, spoons, decorative items, containers
• Processing: Soak horn in boiling water for 30-60 minutes until pliable, press in molds, hold shape until cool

Plant Gums and Resins

Many plants exude sticky substances that function as natural polymers:

Gum Arabic

Exuded by acacia trees, particularly Acacia senegal:

• Properties: Water-soluble, forms viscous solutions, excellent adhesive
• Applications: Paper adhesive, watercolor paint binder, ink thickener, pharmaceutical coating, food stabilizer
• Collection: Score bark of acacia trees; collect dried gum nodules after 3-5 weeks
• Preparation: Dissolve in warm water (1 part gum to 2 parts water), strain through cloth

Pine and Spruce Resin

Coniferous trees produce resin that serves multiple polymer functions:

• Properties: Sticky when warm, hard and brittle when cool, dissolves in oils and alcohol
• Applications: Waterproofing (boats, roofs), adhesive, varnish ingredient, torch fuel, sealing wax
• Collection: Score bark in warm weather; collect resin that flows out
• Processing: Melt gently, strain through cloth to remove debris. Mix with oil for varnish, with beeswax for waterproofing compound, or use pure as sealing material

Birch Bark Tar

One of humanity’s oldest adhesives, produced by dry distillation of birch bark:

1. Pack birch bark tightly in a sealed clay pot with a small hole in the bottom
2. Invert over a collection vessel and bury in a fire
3. Heat drives out a thick, dark tar that collects below
4. The tar is a natural polymer adhesive — waterproof, moderately flexible, and strong

Birch bark tar was used to haft stone tools to wooden handles for over 200,000 years. It remains an excellent adhesive for bonding dissimilar materials.

Lac (Shellac)

Produced by the lac insect (Kerria lacca) on trees in South and Southeast Asia:

• Properties: Dissolves in alcohol, dries to a hard, glossy, waterproof film
• Applications: Wood finish, electrical insulation, sealing wax, molding compound
• Processing: Scrape lac deposits from branches, wash to remove wood debris, melt and strain, pour into thin sheets
• Availability: Limited to tropical/subtropical regions where lac insects live

Cellulose-Based Materials

Cellulose is the most abundant polymer on Earth — it forms the structural walls of every plant cell. Processing cellulose into useful materials requires more chemical knowledge but yields remarkable results:

Parchment (Treated Cellulose)

Soaking plant-fiber paper in concentrated sulfuric acid for a few seconds transforms it into a tough, grease-resistant, partially waterproof material:

• The acid partially dissolves and re-bonds the cellulose fibers
• Rinse immediately in water, then in dilute ammonia to neutralize
• The result is much stronger and more water-resistant than the original paper
• Historically called “vegetable parchment” — used for food wrapping and gaskets

Papier-Mâché

Paper pulp mixed with adhesive (flour paste, hide glue, or casein glue) can be molded into rigid shapes:

1. Tear paper or use raw plant fiber pulp
2. Soak in water until soft
3. Mix with adhesive — approximately 1 part glue to 4 parts wet pulp
4. Press into molds or build up layers over a form
5. Allow to dry completely (may take several days)
6. Sand smooth and seal with oil or varnish

Papier-mâché can produce surprisingly strong containers, panels, and even furniture components.

Rawhide

Untanned animal hide is essentially a collagen-cellulose composite polymer:

• Properties: Extremely tough when dry, becomes pliable when wet, can be molded
• Applications: Containers, drum heads, lashing, armor, snowshoe webbing, mallet heads
• Processing: Scrape the hide clean of flesh and hair, stretch and dry under tension
• Shaping: Soak in water until flexible, form over a mold, let dry in place

Composite Natural Polymers

Some of the most useful materials combine multiple natural polymers:

Beeswax-Resin Compound

Mix equal parts beeswax and pine resin by melting together:

• Creates a waterproof, moderately flexible sealant
• Ideal for coating thread (making waxed cord), sealing containers, waterproofing fabric
• Add charcoal powder for gap-filling adhesive properties

Hide Glue with Chalk Filler

Traditional gesso — hide glue mixed with fine chalk (calcium carbonate):

• Creates a hard, smooth, paintable surface on wood
• Apply in multiple thin layers, sanding between coats
• The foundation for painted furniture and artwork for millennia

Starch Polymers

Starch from potatoes, corn, wheat, or rice is a natural polymer:

• Adhesive: Cook starch with water into a paste. Excellent paper adhesive, textile sizing agent
• Moldable material: Thick starch paste mixed with sawdust or fiber can be pressed into molds and dried
• Bioplastic potential: With glycerin added as plasticizer, starch can form flexible films (though they remain water-sensitive)

Selecting the Right Alternative

Need	Best Alternative Polymer	Second Choice
Waterproof coating	Pine resin + oil varnish	Shellac
Moldable hard material	Casein plastic (hardened)	Horn
Flexible sealant	Beeswax-resin compound	Birch bark tar
Strong adhesive	Hide glue	Casein glue
Paint binder	Casein	Gum arabic
Electrical insulation	Shellac	Dried casein
Food-contact container	Rawhide	Birch bark
Gasket material	Rawhide + beeswax	Cork

The best approach for a rebuilding community is to develop expertise with multiple alternative polymers rather than depending on any single source. Each has unique strengths, and in combination they can substitute for most applications that would otherwise require rubber or synthetic plastics.