Brass vs Aluminium vs Carbtech vs Porcelain: Tactile Indicator Material Guide

The Decision You're Actually Making

Every TGSI material choice comes down to four axes: environment (indoor/outdoor, coastal, wet, chemical), traffic (pedestrian only, wheeled, trolleyed, rail-grade), design intent (does the project want patina, or does it want the day-one finish to hold for 20 years?), and lifecycle cost (upfront spend vs replacement cycles). Get those four lined up and the material picks itself.

This guide works through each material honestly (where it belongs, where it doesn't, what it looks like in 10 years) and maps it to the Korb range. No material is "best." The right material is the one that fits the project brief.

Solid Brass: When Patina Is the Point

Brass TGSIs are the benchmark for civic, heritage, and premium commercial projects where the design wants to age visibly. Cartridge brass (C260) and free-machining brass (C385) are the typical TGSI alloys: hard enough for pedestrian traffic, soft enough that heel strike burnishes the crowns into a slightly darker patina over time.

• Aesthetics: Polished LRV starts around 65-72. A full patina forms over 5-7 years in urban air and drops the LRV into the 35-45 range. Patina is not uniform: exposed studs patinate faster than sheltered ones, which is often the look architects are after.
• Durability: Excellent for sheltered external and interior commercial. Dezincification in chloride-rich environments (coastal, pool, chemical wash-down) attacks standard cartridge brass: specify 316 stainless within 5 km of surf coast or switch to dezincification-resistant alloy.
• Slip rating: Korb brass TGSIs are rated P5 wet-pendulum. Nouvel® CarbTop Brass pairs the brass crown with a carborundum (silicon carbide) top where projects specify higher abrasive grip alongside the P5 rating.
• Compliance risk: Because LRV drifts as patina develops, specify brass against its substrate with a 5-percentage-point margin above the minimum. A Bowman-Sapolinski result of exactly 45% on install day will likely drop below 45% in four years.

Korb brass TGSIs: Nouvel® Classic (concealed pressure-fit), Nouvel® CarbTop (pressure-fit, carborundum crown), Nouvel® Dome (hemispherical heritage profile). All three use mechanical pressure-fit into a slightly undersize hole: no adhesive, no epoxy, replaceable individually.

316 Stainless Steel: Specify It and Forget It

Grade 316 stainless is the spec-forget-it material. The molybdenum content (2-3%) gives it a pitting-resistance number (PREN 23-28) that holds up to chloride exposure where 304 eventually stains or pits. For transport, coastal, hospital, and chemically aggressive environments, 316 is the default.

• Aesthetics: Brushed/satin LRV 39-45, stable for decades. The install-day reading is the 20-year reading: Bowman-Sapolinski compliance holds without drift.
• Durability: Handles salt spray, chemical cleaning agents, sustained wet conditions. Accepted under VicRoads RDN 06-05 and the TMR compliant-products register for transport infrastructure.
• Black PVD: Physical Vapour Deposition (chromium carbide or nitride) bonds a hard ceramic layer, not a paint. Realistic colour life 5+ years under commercial heel strike; longer where traffic is contained. A 10-year PVD warranty is aspirational in heavy traffic.
• Slip rating: Korb 316 stainless TGSIs are rated P5 wet-pendulum. Nouvel® CarbTop in 316 adds a carborundum top where specifications call for additional abrasive grip alongside P5.

Korb 316 TGSIs: Nouvel® Classic, Nouvel® CarbTop, Nouvel® Plate (surface-mount retrofit), and Nouvel® Dome.

Polymer: Interior, Retrofit, Budget

Polymer TGSIs earn their place on interior commercial, aged care, schools, and tight-budget retrofits. The colour palette is wider than any metal, which makes contrast compliance easier against unusual substrate colours. UV-stabilised engineering polymer formulations with HALS additives achieve a credible 5-year outdoor warranty: short of FRP but long enough for most interior service lives.

• Where it fits: Interior commercial, schools, aged care, fast retrofits where a mortar bed is impractical. Peel-and-stick polymer tiles install in hours, not days.
• Where it fails: Sustained outdoor UV in tropical/subtropical full sun, heavy trolley traffic (trolleys ride the dome tops and abrade polymer faster than metal), commercial kitchens where cleaning chemistry attacks the binder.
• Fixing: Adhesive-fix (MS polymer or epoxy) or mortar-bed. Adhesive bond is only as good as substrate prep: polymer discrete studs fail in hot-climate retrofits where substrate temperature at install exceeds 50°C.
• LRV drift: Yellow polymer specified at exactly 30% contrast will often fail contrast compliance inside 4 years of outdoor service. Over-specify.

Korb polymer TGSIs: Renzo® Classic (polymer discrete stud, adhesive-fixed, fast retrofit) and Renzo® Tile (polymer integrated tile, 300×300mm, peel-and-stick).

Fibre-Reinforced Composite: Rail, Airport, Heavy Transport

Composite (FRP) integrated tactiles occupy the step between polymer and natural stone. A glass-fibre reinforced polymer matrix carries load better than plain polymer, weathers harder, and holds LRV through wear because the colour runs through the full thickness. FRP is the Australian default on rail platforms, airport concourses, and heavy transport infrastructure: projects that need a 10-year warranty and 20-year service life.

• Durability: Handles cyclic wheeled load (baggage carts, platform trolleys), UV, solvents, mild acids. Typical 10-year colour-fast warranty with CSIRO-tested slip, luminance and wear data.
• Through-colour: Surface wear does not change LRV: contrast compliance holds over the asset life without re-testing.
• Install: Mortar-bed integrated, tile-trade workflow. Slower than peel-and-stick but no adhesive layer to fail.

Korb FRP TGSIs: Renzo® Vanguard (composite integrated, premium option for high-traffic infrastructure).

Porcelain: Through-Body, Civic-Grade

Porcelain integrated tactiles sit in the ISO 13006 Group BIa category: water absorption ≤0.5% by mass, which is what delivers frost resistance and chemical tolerance. The through-body colour is the key spec argument: as the surface wears, LRV does not change, because the exposed material is the same material as day one.

• Durability: PEI Class IV-V abrasion, rated for heavy commercial and transit. Freeze-thaw resistant by ISO 10545-12 cycling, relevant for Canberra, Alpine NSW, Victorian high country.
• Aesthetics: Matte, refined, curated colour palette built for Bowman-Sapolinski compliance against common Australian substrates. Yellow, charcoal, grey and ivory are the four Kahn® Porcelain colours.
• Slip rating: Kahn® Porcelain is rated P5 wet-pendulum: the structured through-body surface delivers the grip without reliance on a surface coating that can wear.

Korb porcelain TGSIs: Kahn® Porcelain (integrated paver, four colours). Rated P5 wet-pendulum per Korb's published range specification.

Natural Stone: Granite and Bluestone

Natural stone TGSIs are a Melbourne heritage specification. Victorian bluestone (olivine basalt from Port Fairy, Kyneton, or the Brunswick/Coburg quarries) has run the city's footpaths and laneways for 150 years. Granite integrated tactile pavers are the standard inset for heavy civic projects: the City of Melbourne's bluestone-and-granite specification pattern uses 300×300×40mm granite TGSI pavers set into bluestone paving.

• Durability: A bluestone paver lasts as long as the stone does, effectively indefinitely. The tactile cones wear at the rate of the stone itself.
• LRV variability: Natural stone has natural LRV variation. Bluestone LRV runs 8-15; granite 15-30+; flamed finishes read lower than honed. This is the compliance trap: every batch of stone needs LRV testing, and the TGSI material must be matched to that batch. Spec paperwork cannot be written in advance: it's a per-delivery decision.
• Cost: 2-4× porcelain on supply. Install cost is comparable. Reserved for signature civic and heritage work.

Korb stone TGSIs: Kahn® Modular (granite), Kahn® Solid Carved (bluestone, Korb's signature product, cones carved from the solid stone).

The Slip-Resistance Truth

Quick Material Selection

• Heritage civic, patina aesthetic: Brass · Nouvel® Classic or CarbTop in brass
• Coastal, transport, or chemical environment: 316 stainless · Nouvel® Classic or CarbTop in 316
• Interior commercial, budget-sensitive: Polymer · Renzo® Classic (discrete) or Renzo® Tile (integrated)
• Rail platform, airport, 20-year service life: Composite · Renzo® Vanguard (FRP integrated)
• Civic plaza, premium through-body: Porcelain · Kahn® Porcelain
• Melbourne heritage, signature architectural: Bluestone · Kahn® Solid Carved
• Retrofit over existing finish: Nouvel® Plate (surface-mount) or Renzo® Tile peel-and-stick