Doc #23 — Materials Properties Handbook

COMPUTED DATA: MATERIALS PROPERTIES REFERENCE

View the Materials Properties Tables → — Structural materials, fasteners, adhesives, substitution guide, and NZ materials production data.

View the generation script → — Python source code and data sources (AS/NZS standards, BRANZ).

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PURPOSE

Engineers selecting materials without property data risk structural failure (wrong alloy for a load-bearing application), wasted scarce materials, and fabrication errors that are costly under isolation. This document provides engineering reference data for materials available in New Zealand under prolonged import disruption, covering metals, timbers, natural fibers, stone and mineral products, animal-derived materials, and existing plastics stocks. For each material class, key mechanical and physical properties are tabulated, along with working characteristics, NZ-specific availability, and practical notes on use. Substitution tables indicate what NZ-available materials can replace imported ones and where performance gaps exist.

All property values are representative ranges drawn from engineering handbooks and NZ-specific sources.¹ Actual values vary with grade, processing, condition, temperature, and moisture content. Where NZ-specific data is available, it is used. Where it is not, international standard values are given with a note. Users making safety-critical decisions should verify values through testing where possible.

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1. METALS

NZ’s post-event metal supply comes from three sources: NZ Steel Glenbrook production (mild steel from ironsand — Doc #89), the Tiwai Point aluminium smelter (if operational and alumina stocks remain — Doc #109), and recycled metals recovered from existing infrastructure, vehicles, and equipment (Doc #90). No stainless steel, chromium, nickel, tungsten, or tin is produced domestically.

1.1 Properties of NZ-Available Metals

Property	Mild steel (NZ Steel)	Cast iron (grey)	Aluminium (Tiwai)	Copper (recycled)	Lead (recycled)	Bronze (Cu-Sn)	Brass (Cu-Zn)
Density (kg/m³)	7,850	7,100–7,300	2,700	8,940	11,340	8,800–8,900	8,400–8,700
Tensile strength (MPa)	370–500	120–250 (tension)	70–180	210–380	12–17	300–500	330–470
Compressive strength (MPa)	~370–500	600–1,200	70–180	210–380	12–16	300–500	330–470
Elastic modulus (GPa)	200–210	80–140	69–72	110–130	13–15	96–120	100–125
Thermal conductivity (W/m·K)	45–55	46–58	200–210	380–400	33–37	50–75	109–120
Melting point (°C)	1,425–1,540	1,150–1,300	660	1,083	327	880–1,000	900–940
Corrosion resistance	Poor — rusts readily in NZ maritime climate	Poor–moderate	Good (oxide film)	Good	Excellent	Good (marine)	Moderate
Machinability	Good	Excellent (grey)	Good	Good	Excellent	Good	Excellent

Sources: Mild steel values from AS/NZS 3678 (structural steel) and NZ Steel product data.² Cast iron from general engineering handbooks.³ Aluminium values for commercially pure (1xxx series) and common alloys; exact alloy depends on Tiwai Point product mix.⁴ Copper, lead, bronze, and brass from standard references; recycled material may vary from these values depending on contamination levels.⁵

1.2 NZ Availability Ratings

Metal	Source	Availability	Notes
Mild steel	NZ Steel Glenbrook (ironsand)	HIGH — primary production continues	Flat products only; no wire rod, rebar, or sections without mill adaptation (Doc #89)
Cast iron	Scrap recycling + foundry (Doc #93)	MODERATE — depends on foundry capacity	Good for castings; requires coke or electric melting
Aluminium	Tiwai Point smelter	UNCERTAIN — depends on alumina stocks and smelter status	If operational, significant tonnage available; if not, limited to recycled stock
Copper	Recycled from wiring, plumbing, motors	MODERATE — large installed base, limited mining	Historical small mines (Kawau Island, Dun Mountain, Thames district); Australian trade is the long-term source
Lead	Recycled from batteries, cable sheathing, flashings	MODERATE	Lead-acid battery recycling is a primary source (Doc #35)
Bronze	Cast from recycled copper + tin (tin is scarce)	LOW — tin must be recycled or traded	Marine fittings, bearings, bushings; tin availability is the constraint
Brass	Cast from recycled copper + zinc (zinc is scarce)	LOW — zinc must be recycled or traded	Existing brass fittings are the main stock; new production limited by zinc

1.3 Working Notes

Mild steel is NZ’s primary structural and fabrication metal. Glenbrook produces a basic carbon steel suitable for construction, tank fabrication, gasifier bodies, ship plate, and general engineering. Without alloying elements (imported), it is not high-strength or stainless steel. Corrosion in NZ’s humid, salt-laden air requires protective coatings — paint, bitumen, or tallow-based treatments. See Doc #89 for production constraints and Doc #94 for welding.

Cast iron is excellent for castings — engine blocks, stove bodies, pipe fittings, machine bases — where compressive strength matters more than tensile strength and where the material does not need to bend or stretch. Machinable and self-lubricating (graphite flakes in grey iron). NZ foundry capability exists and can expand (Doc #93).

Copper is critical for electrical applications (wire, motor windings, transformer coils) and is NZ’s most strategically constrained metal. Every kilogram of copper in NZ should be treated as irreplaceable until trade is established. Recycling from decommissioned buildings, vehicles, and electronics is the primary near-term source.

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2. TIMBERS

NZ’s timber resource is substantial — approximately 1.7 million hectares of plantation forest, predominantly radiata pine, plus native forest reserves (Doc #99).⁶ Timber is the one structural material NZ can produce indefinitely from a renewable resource.

2.1 Properties of NZ Timber Species

Property	Radiata pine	Douglas fir	Macrocarpa	Rimu	Totara	Red beech
Density, air-dry (kg/m³)	480–530	480–540	430–510	530–610	400–470	600–680
Bending strength MOR (MPa)	70–90	80–100	60–80	65–95	55–75	90–115
Modulus of elasticity MOE (GPa)	8–10	10–13	7–9	8–11	6–8	11–14
Compressive strength (MPa)	35–50	40–55	30–45	30–48	25–40	45–60
Shear strength (MPa)	8–11	8–12	7–10	8–11	7–9	10–14
Natural durability (ground contact)	Very low — rots quickly	Low–moderate	Moderate–high	Moderate	High	Moderate
Treatability (preservative uptake)	Excellent (sapwood)	Poor (heartwood)	Poor	Poor	Moderate	Poor
Primary NZ use	General construction, framing	Structural, poles	Fencing, outdoor furniture	Flooring, finishing	Carving, marine, posts	Heavy construction, bridges

Sources: NZ Timber Design Guide (NZ Wood / BRANZ), NZS 3603 (Timber Structures Standard), and published data from Scion (NZ Forest Research Institute).⁷ Values are for air-dry timber at approximately 12% moisture content. Green (freshly felled) timber has lower strength — approximately 60–80% of air-dry values depending on species and property.

2.2 NZ Availability Ratings

Species	Availability	Stock estimate	Notes
Radiata pine	VERY HIGH	~1.6 million ha plantation; ~450–550 million m³ standing8	Dominant species; fast-growing (25–30 year rotation); readily available nationwide
Douglas fir	MODERATE	~90,000–110,000 ha plantation, mostly Canterbury/Otago	Stronger than radiata; slower-growing (35–45 year rotation)
Macrocarpa	MODERATE	Widely planted as shelter; ~40,000–80,000 ha estimated	Naturally durable heartwood; variable quality
Rimu	LOW — conservation restrictions	Standing native forest; not plantation-grown	Logging restrictions likely relaxed under emergency; excellent finish timber
Totara	LOW — conservation restrictions	Scattered in native forest; some farm plantings	Highly durable; traditional Maori building and carving timber
Red beech	LOW–MODERATE	Extensive native stands, mostly South Island	Very strong; excellent for heavy structural use; slow-growing

2.3 Working Notes

Radiata pine is NZ’s workhorse timber. It is abundant, fast-growing, easy to work, and readily takes preservative treatment (sapwood). Its weakness is durability — untreated radiata rots rapidly in ground contact or exposed conditions (NZ Building Code requires H3.2 or higher treatment for exposed timber, H5 for ground contact).⁹ When CCA and boron treatment chemicals are exhausted, alternative preservation methods become necessary: charring (shou sugi ban technique), pine tar coating (Doc #102), hot linseed oil treatment, or accepting shorter service life and planning for replacement. Alternatively, specify naturally durable species (macrocarpa heartwood, totara) for ground-contact and exposed applications.

Douglas fir is stronger and stiffer than radiata, making it preferred for structural applications where spans are long or loads heavy. It is also more naturally durable than radiata, though still not suitable for ground contact without treatment. NZ’s Douglas fir plantations are concentrated in the South Island.

Native timbers (rimu, totara, beech, kahikatea, matai) offer properties — natural durability, hardness, beauty — that plantation species cannot match. Under recovery conditions, carefully managed selective harvesting of native timber for specific high-value applications (boat keels, marine piles, bearing surfaces, tool handles) is a rational use of the resource. Totara was the primary building timber of pre-European Maori construction and waka (canoe) building, and traditional knowledge of its selection and working is held in Maori communities.¹⁰

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3. NATURAL FIBERS

3.1 Properties of NZ-Available Fibers

Property	Harakeke (muka)	Wool	Hemp	Cotton (stockpile only)
Tensile strength (MPa)	440–990	120–170	550–900	300–600
Elastic modulus (GPa)	14–33	2–4	30–70	5–13
Elongation at break (%)	2–5	25–45	1–4	3–10
Density (g/cm³)	1.3–1.5	1.28–1.32	1.4–1.5	1.5–1.6
Moisture absorption (%)	10–15 (ambient); 30–40+ (saturated)	13–18 (ambient); up to 33	8–12	7–11
Rot resistance	Moderate (needs drying)	Good (lanolin)	Poor (untreated)	Poor
NZ availability	HIGH — native, abundant	VERY HIGH — major industry	LOW — minimal NZ production	NONE — import only

Sources: Harakeke data from Carr et al., 2005 and Scion research.¹¹ Wool from NZ Wool Testing Authority and international fiber science references.¹² Hemp and cotton from standard textile engineering references.¹³

3.2 Working Notes

Harakeke (Phormium tenax) is NZ’s most important domestic fiber for rope, cordage, sacking, and coarse textiles. Tensile strength is comparable to manila hemp (abaca), with the strongest cultivars exceeding it.¹⁴ See Doc #100 for full processing chain, cultivar selection, and scaling. Performance gap vs. synthetic rope: heavier when wet, requires maintenance (drying, tarring for marine use), more variable in quality. These gaps are real but manageable — natural fiber rope served all maritime, agricultural, and industrial needs before synthetic alternatives became widespread in the mid-20th century.¹⁵

Wool is NZ’s primary textile fiber — approximately 120,000–140,000 tonnes per year production.¹⁶ Excellent for clothing, insulation, blankets, and filtration. Not well suited to rope (too stretchy, too valuable). Complementary to harakeke: wool for clothing, harakeke for cordage and industrial textiles.

Hemp would be an excellent complementary fiber crop if seed stock is available, but NZ’s pre-event hemp industry is minimal — limited to a small number of licensed growers producing primarily for seed oil and niche textiles.¹⁷ Not a near-term resource.

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4. STONE, MINERAL, AND CEMENTITIOUS MATERIALS

4.1 Properties

Property	Concrete (20 MPa mix)	Fired brick	Limestone	Basalt	Granite
Density (kg/m³)	2,300–2,400	1,800–2,200	2,300–2,700	2,800–3,000	2,600–2,800
Compressive strength (MPa)	20–40 (by design)	10–70	20–80	100–300	100–250
Tensile strength (MPa)	2–4 (weak in tension)	2–5	3–8	10–30	7–25
Elastic modulus (GPa)	20–30	5–25	20–60	60–100	40–70
Thermal conductivity (W/m·K)	1.0–1.8	0.6–1.3	1.3–2.0	1.3–2.3	2.0–3.5
Corrosion / weathering	Good if reinforcement protected	Excellent (fired)	Soluble in acid rain; weathers slowly	Excellent	Excellent

Sources: Concrete properties per NZS 3101 (Concrete Structures Standard) and NZ Ready Mixed Concrete Association data.¹⁸ Stone properties from general geological and engineering references; NZ-specific stone data from GNS Science publications.¹⁹

4.2 NZ Availability

Material	Source	Availability
Concrete	NZ cement (Golden Bay Cement, Holcim — limestone + pozzolan); aggregate from NZ quarries	HIGH — NZ produces cement domestically (Doc #97)
Fired brick	NZ clay deposits (Huntly, Canterbury, others); existing NZ brick manufacturers	MODERATE — existing industry, expandable
Limestone	Golden Bay, Otorohanga, Te Kuiti, other NZ deposits	HIGH — widespread deposits
Basalt	Volcanic regions, especially Auckland, Northland, Central Plateau	HIGH — abundant in volcanic NZ
Granite	Limited in NZ — some Fiordland, Coromandel, Stewart Island exposures	LOW — NZ has limited granite; basalt and greywacke are the common hard stones
Pounamu (nephrite jade)	West Coast South Island	LOW — limited supply, culturally significant

4.3 Working Notes

Concrete remains NZ’s primary mass construction material under recovery conditions. NZ produces cement from domestic limestone and volcanic pozzolan (Doc #97). The constraint is reinforcing steel — without rebar (which Glenbrook does not currently produce — Doc #89), reinforced concrete becomes difficult. Unreinforced concrete and mass concrete (foundations, walls, dams) are feasible. Timber and harakeke fiber have been investigated as alternative reinforcement but with inferior performance to steel rebar.²⁰

Pounamu (greenstone, nephrite jade) is an engineering material as well as a cultural taonga. Nephrite is extremely tough — among the toughest natural materials known — with a compressive strength of 700–1,000+ MPa and excellent resistance to fracture. Historically used by Maori for adze blades (toki), chisels, and weapons. Its toughness (as distinct from hardness) makes it superior to many stones for cutting tools. However, supply is limited to the West Coast of the South Island, extraction is labour-intensive, and its cultural significance means any use must be in partnership with mana whenua (Ngai Tahu).²¹

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5. ANIMAL-DERIVED MATERIALS

Property	Leather (cattle)	Tallow (rendered fat)	Bone	Horn
Density (kg/m³)	860–1,020	900–920	1,800–2,000	1,200–1,350
Tensile strength (MPa)	10–40	n/a (liquid/solid fat)	100–150 (compact bone)	30–80
Thermal conductivity (W/m·K)	0.14–0.16	0.17–0.21	0.3–0.6	0.35–0.50
Key properties	Flexible, durable, water-resistant	Lubricant, soap feedstock, candle wax	Hard, workable, takes polish	Tough, flexible, workable
NZ availability	HIGH — large livestock industry	HIGH — byproduct of meat processing	HIGH	HIGH

Sources: Leather properties from tanning industry references.²² Tallow from NZ meat processing industry data.²³ Bone and horn from materials science references.²⁴

5.1 Working Notes

Leather requires tanning — a chemical process using either vegetable tannins (from NZ bark sources: manuka, kanuka, tanekaha) or chrome salts (imported, finite). Vegetable tanning produces functional leather but is slower (weeks to months vs. hours to days for chrome tanning) and produces a stiffer product.²⁵ NZ has abundant hides from cattle and sheep slaughter. Leather is essential for footwear, belting (power transmission), gaskets, harness, and protective clothing. See Doc #101 for tanning processes.

Tallow is one of NZ’s most versatile animal products under recovery conditions: lubricant for machinery (inferior to petroleum lubricant but functional for many applications — Doc #34), soap feedstock (Doc #37), candle wax, leather dressing, and wood preservative. NZ processes approximately 140,000–160,000 tonnes of tallow per year under normal conditions.²⁶

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6. PLASTICS (EXISTING STOCK ONLY)

NZ has no domestic petrochemical feedstock for plastic manufacture.²⁷ All plastic in NZ is existing stock — in products, packaging, pipes, containers, building materials, vehicles, and waste streams. Plastics are a depleting resource to be conserved, repurposed, and recycled where possible.

6.1 Common Plastics in NZ Infrastructure

Type	Common uses in NZ	Density (kg/m³)	Tensile strength (MPa)	Service temp max (°C)	UV resistance	Degradation concern
HDPE	Water pipe, milk bottles, tanks	940–970	25–45	80–120	Moderate	Embrittles with UV over years–decades
PVC	Drain pipe, cable insulation, guttering	1,300–1,450	40–60	60–80	Poor–moderate	Embrittles; releases HCl if burned
PP	Containers, rope, agricultural film	900–910	30–40	100–130	Poor	Degrades significantly with UV
PET	Bottles, some textiles	1,330–1,400	55–75	70–120	Moderate	Relatively stable in storage
LDPE	Plastic bags, agricultural film, cling wrap	910–940	8–20	80–100	Poor	UV-degrades rapidly when exposed
Nylon (PA)	Rope, fishing line, gears, bearings	1,120–1,150	60–85	80–150	Moderate	Absorbs moisture; stable otherwise

Sources: General polymer engineering references.²⁸

6.2 Working Notes

Do not burn plastics for disposal — most release toxic fumes (PVC releases hydrochloric acid gas). Plastic in good condition should be conserved for its original function or repurposed. PVC pipe in NZ’s water and drainage infrastructure is a long-lived asset — expected service life of 50–100+ years if undamaged — and should be maintained rather than replaced.²⁹

Nylon and polypropylene rope is finite and irreplaceable (Doc #100). All synthetic rope should be rationed and reserved for applications where harakeke rope cannot substitute — specifically high-strength, low-stretch applications like halyard rigging, safety lines, and lifting slings. Harakeke rope should progressively replace synthetic for general-purpose cordage.

Recycling is limited without industrial chemical processing. Thermoplastics (HDPE, PP, PET) can be melted and remoulded, but this requires controlled heating (temperature must stay within a workable range to avoid decomposition), moulds or forming equipment, and careful sorting by polymer type — mixed plastics produce weak, unreliable products. This extends the useful life of plastic stock but does not create new material, and each recycling cycle degrades the polymer. Thermosets (epoxies, polyesters in fibreglass) cannot be remelted.

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7. SUBSTITUTION TABLES

These tables indicate what NZ-available materials can substitute for commonly imported materials. The performance gap column is critical — most substitutions involve genuine compromises that engineers and planners must account for.

7.1 Metals Substitution

If you need… (imported)	Consider… (NZ-available)	Performance gap	Notes
Stainless steel	Mild steel + paint/bitumen coating	Corrodes without maintenance; requires periodic recoating	Acceptable for structure; not for food-contact or chemical applications
Structural sections (I-beam, channel)	Fabricated plate sections (welded) or timber	Welded sections heavier, slower to produce; timber has lower span/load capacity	Welded plate I-beams are standard practice for large structures
Rebar (reinforcing bar)	Deformed wire from rod (if rod production achieved); or timber/harakeke reinforcement	Timber/fiber reinforcement is much weaker than steel rebar	Unreinforced mass concrete may be preferable for some applications
Copper (new)	Recycled copper; aluminium for electrical (if available)	Aluminium has 60% of copper’s conductivity; requires larger cross-section	Prioritise copper for motors and transformers; aluminium for overhead lines
Zinc (for galvanising)	Paint, bitumen, tallow coating, pine tar	All alternatives require periodic maintenance; shorter service life	Accept higher maintenance burden
Tin (for tinplate, solder)	Lead-based solder (health risk); wax or lacquer for food containers	Lead solder is toxic — not for water or food contact; wax coating is short-lived	Glass or ceramic containers for food storage where possible
Nickel, chromium	No NZ substitute	No substitute for corrosion-resistant alloys	Conserve existing stainless steel for critical applications (surgical, food processing)

7.2 Fiber and Textile Substitution

If you need… (imported)	Consider… (NZ-available)	Performance gap	Notes
Nylon rope	Harakeke rope	Heavier wet, less elastic, requires maintenance (drying, tarring)	Functional for nearly all applications; use safety factor of 5:1 to 10:1
Cotton fabric	Wool (clothing); harakeke (industrial textile)	Wool is warmer/heavier than cotton; harakeke is coarser	No NZ-grown cotton substitute; wool is superior for cold-climate clothing
Fibreglass (GRP)	Harakeke-fiber composite (experimental)	Lower strength-to-weight; requires development	Research-stage only; for boat hulls, timber construction is proven
Polypropylene baling twine	Harakeke twine	Must be protected from persistent moisture	Functional substitute; NZ historically used flax twine for this

7.3 Construction Material Substitution

If you need… (imported)	Consider… (NZ-available)	Performance gap	Notes
Treated radiata pine (CCA)	Macrocarpa heartwood; totara; charred radiata; pine-tar-treated radiata	Natural durability species are scarcer; charring/tar treatment less proven at scale	For ground contact: use naturally durable species. For above ground: charring or tar is adequate
Plywood (glued panels)	Sawn timber; laminated timber with casein or hide glue	Less dimensionally stable; thicker and heavier for equivalent structural performance	Casein glue (from milk protein) is moderately water-resistant but not waterproof; hide glue fails in wet conditions
Glass (new)	NZ glass production from Parengarenga silica sand (Doc #98)	NZ glass production must be established; quality may be lower initially	Existing glass stock should be conserved and recycled
Plastic pipe (new)	Existing PVC/PE pipe (maintain); clay pipe; cast iron pipe; timber pipe (large diameter)	Clay and iron pipe are heavier and harder to install; timber pipe is short-lived	Protect existing plastic pipe infrastructure — it lasts decades
Rubber (seals, gaskets, hose)	Leather; cork (not NZ-grown); tallow-impregnated harakeke; recycled rubber	All alternatives are significantly inferior for dynamic seals and high-pressure applications	NZ’s hardest materials gap; recycled rubber extends existing stock

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8. DATA SOURCES AND LIMITATIONS

8.1 Primary sources for NZ-specific data

• NZS 3603:1993 — Timber Structures Standard (NZ timber properties and design values)
• NZS 3101:2006 — Concrete Structures Standard
• AS/NZS 3678 — Structural steel (covers NZ Steel product)
• NZ Timber Design Guide (NZ Wood / BRANZ) — comprehensive NZ timber data
• Scion (NZ Forest Research Institute) — timber and natural fiber research³⁰
• GNS Science — geological, mineral, and stone data for NZ³¹
• NZ Steel / BlueScope technical product data sheets³²
• BRANZ (Building Research Association of NZ) — building materials performance data³³

8.2 International reference sources

Where NZ-specific data is unavailable (metals other than NZ Steel products, general polymer properties, animal products), values are drawn from standard engineering references:

• Marks’ Standard Handbook for Mechanical Engineers
• ASM Metals Handbook
• Materials Science and Engineering (Callister & Rethwisch)
• Engineering Toolbox (www.engineeringtoolbox.com)

8.3 Limitations

This document provides representative ranges, not guaranteed design values. The following limitations apply:

1. Recycled metals may have properties different from published values due to contamination (tramp elements in recycled steel, impurities in recycled copper — Doc #90).
2. Timber properties vary significantly with moisture content, growth rate, defects (knots, grain deviation), and position within the tree. The values in Section 2 are for clear, straight-grained, air-dry timber. Structural design must account for defects using the grading system in NZS 3603.
3. Natural fiber properties vary with cultivar, growing conditions, extraction method, and age. The harakeke values span a wide range reflecting this variability. Production rope should be destructively tested to establish actual working loads (Doc #100).
4. Concrete properties depend entirely on mix design, aggregate quality, water-cement ratio, curing, and reinforcement. The values in Section 4 are for a standard 20–40 MPa mix — actual properties are specified by the engineer for each application.
5. Nuclear winter effects on material supply are addressed in individual documents (Doc #99 for timber growth rates, Doc #74 for pastoral products, Doc #89 for steel production). This document provides baseline properties, not production volumes.

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CROSS-REFERENCES

Topic	Document
Steel production and constraints	Doc #89 — NZ Steel Glenbrook
Scrap metal recycling	Doc #90 — Scrap Metal as Resource
Machine shop operations	Doc #91 — Machine Shop Operations
Foundry and casting	Doc #93 — Foundry Work
Welding consumables	Doc #94 — Welding Electrode Fabrication
Cement and concrete	Doc #97 — Cement and Concrete
Glass production	Doc #98 — Glass Production
Timber processing	Doc #99 — Timber Processing
Harakeke fiber	Doc #100 — Harakeke Fiber Processing
Leather tanning	Doc #101 — Tanning and Leather
Charcoal and pine tar	Doc #102 — Charcoal Production
Wire and fencing	Doc #105 — Wire Drawing and Fencing
Engineering reference tables	Doc #17 — Engineering Reference Tables
Lubricants	Doc #34 — Lubricant Production

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FOOTNOTES

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1. Property values in this document are representative ranges compiled from NZ standards, international engineering handbooks, and published research. They are suitable for preliminary design and planning. For safety-critical applications, values should be verified against the relevant NZ or international standard and, where possible, confirmed by material testing. Primary sources include Marks’ Standard Handbook for Mechanical Engineers (various editions), ASM Metals Handbook (ASM International), NZ standards (NZS 3603, NZS 3101, AS/NZS 3678), and Scion (NZ Forest Research Institute) publications.↩︎

2. NZ Steel / BlueScope Steel NZ product data and specifications. AS/NZS 3678:2016 (Structural steel — Hot-rolled plates, floorplates and slabs) covers grades produced at Glenbrook. See BlueScope Steel NZ technical data sheets. https://www.bluescopenzsteel.co.nz/↩︎

3. Cast iron properties: Grey cast iron (ASTM A48 / AS 1830 equivalent). Compressive strength of grey cast iron is 3–5 times its tensile strength — this is a defining characteristic. See: ASM Metals Handbook, Volume 1: Properties and Selection — Irons, Steels, and High-Performance Alloys, ASM International.↩︎

4. Aluminium properties depend strongly on alloy and temper. Tiwai Point produces primary aluminium ingot, which would need to be alloyed and processed downstream. Commercially pure aluminium (1050, 1100) has tensile strength ~70–130 MPa; common alloys (6061-T6) reach ~310 MPa. See: Aluminium Design Manual, The Aluminium Association; Rio Tinto NZAS operational information.↩︎

5. Copper, lead, bronze, and brass properties from ASM Metals Handbook and standard metallurgical references. Recycled copper may contain impurities (tin, lead, iron) that affect conductivity and mechanical properties. Electrolytic refining (which requires sulfuric acid — Doc #113) can purify recycled copper to high conductivity; without refining, recycled copper is adequate for mechanical applications but may be sub-optimal for electrical use.↩︎

6. NZ plantation forest area: approximately 1.7 million hectares as of the early 2020s, with ~90% radiata pine. See: Ministry for Primary Industries (MPI), National Exotic Forest Description (NEFD), published annually. https://www.mpi.govt.nz/↩︎

7. NZ timber properties: NZ Timber Design Guide (NZ Wood / BRANZ), which consolidates data from NZS 3603:1993 (Timber Structures Standard) and Scion research publications. Species-specific data from Scion’s Timber Properties database. Values for bending strength (MOR — Modulus of Rupture) and MOE (Modulus of Elasticity) are for small clear specimens; structural design values are lower to account for defects and size effects.↩︎

8. NZ plantation forest area: approximately 1.7 million hectares as of the early 2020s, with ~90% radiata pine. See: Ministry for Primary Industries (MPI), National Exotic Forest Description (NEFD), published annually. https://www.mpi.govt.nz/↩︎

9. NZ Building Code treatment requirements: NZ Building Code B2/AS1 specifies hazard class (H-class) requirements for timber in different exposure conditions. H3.2 for timber exposed to weather but not in ground contact; H5 for timber in ground contact. Treatment is typically CCA (copper-chrome-arsenic) for exterior use or boron for interior/dry use. See: BRANZ, Timber Treatment. https://www.branz.co.nz/↩︎

10. Totara in Maori construction: Totara (Podocarpus totara) was the primary timber for Maori building and carving due to its straight grain, workability, and exceptional natural durability. Waka (canoe) hulls, palisade posts (pou), and carved panels (whakairo) were typically totara. See: Best, E., “The Maori,” Polynesian Society Memoirs, 1924. Also: Te Papa Tongarewa ethnographic documentation.↩︎

11. Harakeke fiber properties: Carr, D.J., Cruthers, N.M., Laing, R.M., and Niven, B.E., “Fibre from Three Cultivars of New Zealand Flax (Phormium tenax),” Textile Research Journal, 75(2), 2005, pp. 93–98. https://doi.org/10.1177/004051750507500201. Also: Scion research on harakeke as a natural fiber for composites and industrial use.↩︎

12. Wool properties: NZ Wool Testing Authority (NZWTA) and international fiber property data. Wool tensile strength is low compared to plant fibers but wool’s elasticity (25–45% elongation) is a defining advantage for textile applications — it resists permanent deformation and recovers shape. See: Wool Science (Simpson and Crawshaw, eds.), Woodhead Publishing.↩︎

13. Hemp and cotton fiber properties: Standard textile engineering references. See: Kozlowski, R. (ed.), Handbook of Natural Fibres, Woodhead Publishing, 2012. Also: Bledzki, A.K. and Gassan, J., “Composites reinforced with cellulose based fibres,” Progress in Polymer Science, 24(2), 1999.↩︎

14. Harakeke vs. manila hemp comparison: Manila hemp (abaca, Musa textilis) has typical tensile strength of 400–980 MPa. The strongest harakeke cultivars (e.g., Tapamangu) reach the upper end of this range. See: Carr et al., 2005 (footnote 10) for harakeke data; Bledzki and Gassan, 1999 for abaca comparison values.↩︎

15. Natural fiber cordage history: Synthetic ropes (nylon, polypropylene, polyester) became commercially dominant from the 1950s–1960s. Prior to this, all rope for maritime, agricultural, and industrial use was natural fiber — primarily manila, sisal, hemp, and locally available plant fibers. See: Tyson, W., Rope: A History of the Hard Fibre Cordage Industry, Wheatland Journals, 1966.↩︎

16. NZ wool production: approximately 120,000–140,000 tonnes per year. Beef + Lamb New Zealand Economic Service, Compendium of New Zealand Farm Facts. https://beeflambnz.com/↩︎

17. NZ hemp industry: NZ permits licensed industrial hemp cultivation under the Misuse of Drugs (Industrial Hemp) Regulations 2006. As of the early 2020s, the planted area is small — typically under 1,000 ha — and focused on seed oil and fiber trials rather than large-scale textile production. See: MPI (Ministry for Primary Industries) hemp industry reporting. https://www.mpi.govt.nz/↩︎

18. NZ concrete standards and properties: NZS 3101:2006 (Concrete Structures Standard); NZ Ready Mixed Concrete Association specifications. Standard structural concrete in NZ is specified at 20–40 MPa compressive strength at 28 days. Higher-strength mixes (50–80+ MPa) are achievable but require careful aggregate selection and mix design.↩︎

19. NZ stone properties: GNS Science geological publications; BRANZ Building Stone in New Zealand fact sheets. NZ’s common building stones include greywacke (a hard sandstone, widespread), basalt (volcanic regions), and Oamaru stone (a soft limestone, primarily South Island). Granite is rare in NZ compared to Australia or the Northern Hemisphere. https://www.gns.cri.nz/↩︎

20. Alternative concrete reinforcement: Timber and natural fiber reinforcement of concrete has been researched but remains experimental. Bamboo reinforcement has been studied internationally; NZ does not have structural bamboo species. Harakeke fiber reinforcement of cement composites has been investigated at NZ universities (see Scion and University of Auckland research) but provides significantly less tensile reinforcement than steel rebar. Unreinforced mass concrete structures (gravity dams, thick walls, foundations) do not require reinforcement by design.↩︎

21. Pounamu properties: Nephrite jade has a Mohs hardness of 6–6.5 and an exceptionally high fracture toughness (~10–20 MPa·m^0.5), making it one of the toughest natural materials. Its interlocking fibrous crystal structure resists crack propagation. See: Broz, M.E. et al., “Microhardness, toughness, and modulus of Mohs scale minerals,” American Mineralogist, 91, 2006. Culturally, pounamu is a taonga under Ngai Tahu authority per the Ngai Tahu Claims Settlement Act 1998.↩︎

22. Leather properties: Variable depending on tanning method, animal source, and thickness. Cattle leather in NZ is widely available from the meat processing industry. See: LASRA (Leather and Shoe Research Association of NZ — now part of NZ Leather and Shoe Research Association). General tanning chemistry from standard references.↩︎

23. NZ tallow production: NZ exports approximately 140,000–160,000 tonnes of tallow and tallow-based products per year, a byproduct of the meat processing industry. See: MPI (Ministry for Primary Industries) export data; Beef + Lamb NZ statistics.↩︎

24. Bone and horn properties: Bone (compact/cortical) has a compressive strength of approximately 170–190 MPa and tensile strength of 100–150 MPa. Horn (keratin-based) is tough and flexible. Properties from: Currey, J.D., Bones: Structure and Mechanics, Princeton University Press, 2002. Also: general biomaterials engineering references.↩︎

25. Tanning timescales: Chrome tanning typically completes in 1–3 days; vegetable tanning requires 3–12 weeks depending on hide thickness and tannin concentration, with heavy hides sometimes requiring several months. Vegetable-tanned leather is firmer, thicker, and less elastic than chrome-tanned leather. See: Covington, A.D., Tanning Chemistry: The Science of Leather, Royal Society of Chemistry, 2009.↩︎

26. NZ tallow production: NZ exports approximately 140,000–160,000 tonnes of tallow and tallow-based products per year, a byproduct of the meat processing industry. See: MPI (Ministry for Primary Industries) export data; Beef + Lamb NZ statistics.↩︎

27. NZ petrochemical feedstock: NZ has small natural gas fields (Taranaki basin) but no naphtha cracker or ethylene production facility. Methanex NZ produces methanol from natural gas but not polymer-grade feedstocks. Without imported ethylene, propylene, or other monomers, large-scale plastic manufacture is not feasible. See: MBIE (Ministry of Business, Innovation and Employment), NZ energy sector data.↩︎

28. Polymer properties: Standard references include Polymer Handbook (Brandrup and Immergut, eds., Wiley-Interscience) and Engineering Plastics (ASM International). UV degradation rates are highly variable with formulation, stabiliser package, and exposure conditions. The “service temp max” values are approximate continuous service temperatures; short-term exposure to higher temperatures may be acceptable.↩︎

29. PVC pipe service life: BRANZ and NZ pipe manufacturers (Marley, Iplex/Aliaxis) specify design life of 50–100 years for PVC pressure pipe under normal operating conditions. In-ground pipe protected from UV has indefinite life if not mechanically damaged. See: Plastics NZ / Plastics Industry Pipe Association of Australia and NZ (PIPA). https://www.branz.co.nz/↩︎

30. Scion (NZ Forest Research Institute): NZ’s crown research institute for forestry and wood products. Located in Rotorua. Publishes NZ-specific timber properties, treatment research, and natural fiber data. https://www.scionresearch.com/↩︎

31. GNS Science (Institute of Geological and Nuclear Sciences): NZ’s geoscience research institute. Publishes geological maps, mineral occurrence data, and materials characterisation for NZ rocks and minerals. https://www.gns.cri.nz/↩︎

32. NZ Steel / BlueScope Steel NZ product data and specifications. AS/NZS 3678:2016 (Structural steel — Hot-rolled plates, floorplates and slabs) covers grades produced at Glenbrook. See BlueScope Steel NZ technical data sheets. https://www.bluescopenzsteel.co.nz/↩︎

33. BRANZ (Building Research Association of New Zealand): NZ’s independent building research organisation. Publishes guidance on building materials performance, durability, and compliance with the NZ Building Code. https://www.branz.co.nz/↩︎