materials library / classes
NEURODESIGN® · 49 CLASSES · 8 FAMILIES
Material classes
A material class is what a thing is made of, independent of who made it. This is the level evidence actually sits at, because no study has ever tested a named commercial product. Research tests wool, or wood, or absorptive treatment, and a product can inherit that only through its own measured attributes, only as far as those attributes match what was tested.
4 of these 49 classes carry a record from the research corpus. The other 45 carry none. That is the state of the field rather than a gap in the reading, and it is the most useful number on this page.
Animal and plant fibre 6
Fibres with high porosity and low thermal effusivity. The acoustic and tactile workhorses of a guestroom, and the class where composition disclosure is weakest because backings, adhesives and treatments are rarely named.
- WoolKeratin fibre, typically used as pile or felt. Hygroscopic, inherently flame resistant without added retardants, and porous enough to absorb sound at speech frequencies when used in depth.no evidence
- CottonCellulosic fibre used in bedding, sheers and upholstery. High moisture regain, low resilience under compression.no evidence
- LinenBast fibre from flax. Stiffer hand than cotton, high moisture conductivity, characteristic irregular texture at a scale the fingertip resolves.no evidence
- SilkProtein filament fibre. Very low surface roughness, high specularity relative to other textiles.no evidence
- Jute, sisal and seagrassCoarse bast and leaf fibres woven into flooring and wallcovering. High texture wavelength, low compliance, limited stain resistance.no evidence
- LeatherTanned hide. Thermal effusivity close to skin under sustained contact, and a distinctive odour profile that is a deliberate product attribute rather than a defect.no evidence
Synthetic fibre and polymer 8
The dominant contract materials by volume. Strong on durability and cleanability, and the class where semi-volatile emissions and additive chemistry sit largely outside current certification.
- NylonPolyamide fibre, the default contract carpet face fibre. High resilience and abrasion resistance.no evidence
- Polyester and recycled PETPolyester fibre, increasingly from recycled bottle stock, used both as textile and as needle-punched acoustic board.no evidence
- PolypropyleneOlefin fibre. Hydrophobic, stain resistant by chemistry rather than by treatment, low resilience.no evidence
- Viscose and lyocellRegenerated cellulose. Silk-like hand at lower cost, with markedly different wet strength and process chemistry between the two.no evidence
- Vinyl and PVCPlasticised polyvinyl chloride in sheet, tile and wallcovering form. Durable and cleanable, and the principal interior source of semi-volatile plasticiser exposure.no evidence
- LinoleumLinseed oil, rosin, wood flour and limestone on a jute backing. Bio-based, with a characteristic and persistent oxidation odour during curing.no evidence
- RubberNatural or synthetic elastomer flooring. High compliance, high impact sound reduction, distinctive odour.no evidence
- Polyurethane and acrylic solid surfaceCast polymer and mineral composite worked as a continuous seamless surface.no evidence
Wood and plant structure 7
The only material family in this library with a dedicated psychophysiological literature behind it, including two systematic reviews rated at the corpus's highest evidence strength and shortest translation distance.
- Solid hardwoodSawn hardwood, used as flooring, panelling and joinery. Grain figure gives a pattern with statistical structure rather than a repeat.3 records
- Solid softwoodSawn coniferous timber. Lower density and hardness than hardwood, more pronounced grain contrast, higher volatile terpene emission when unfinished.3 records
- Engineered wood and plywoodLaminated veneer over a stable core. Visually a wood surface, compositionally a glue-bearing assembly.3 records
- Particleboard and MDFWood particles or fibres bound under pressure. Substrate rather than surface, and historically the dominant interior formaldehyde source.no evidence
- BambooGrass stem processed into strand or laminated board. Mechanically closer to a dense hardwood than to timber, with adhesive content that varies by format.no evidence
- CorkSuberised bark cell structure. Closed-cell, high compliance, low thermal effusivity and meaningful impact sound reduction, all from the same cellular geometry.no evidence
- Rattan and caneWoven palm stem, typically as an open screen. Acoustically transparent, visually a regular open lattice.no evidence
Stone and earth 9
High density, high thermal effusivity, acoustically reflective. The class most often carrying a wellness narrative and least often carrying any human-response evidence at all.
- LimestoneSedimentary calcium carbonate. Porous by stone standards, matte, with a narrow spectral reflectance range.no evidence
- MarbleMetamorphosed carbonate with visible veining and, in pale varieties, subsurface light scattering.no evidence
- TravertineBanded calcium carbonate with characteristic voids, which may be filled or left open. Filled and unfilled travertine are acoustically and tactilely different materials.no evidence
- Granite and quartziteDense silicate stone. High hardness, low porosity, high specularity when polished.no evidence
- SlateFine-grained metamorphic rock that cleaves to a naturally textured face. Dark, low reflectance, high within-surface variation.no evidence
- TerrazzoAggregate in a cement or resin matrix, ground flat. Pattern is aggregate-driven, statistically uniform at room scale and highly varied at hand scale.no evidence
- Lime and clay plasterMineral plaster applied wet and finished by hand. Vapour open, matte, with a hand-applied texture that has no repeat at all.no evidence
- Gypsum plaster and boardThe default wall substrate. Acoustically reflective at the surface, and a significant absorber only at low frequency through panel resonance.no evidence
- ConcreteCement, aggregate and water, left exposed. High thermal mass, high effusivity, acoustically hard.2 records
Ceramic and glass 5
Fired and fused mineral surfaces. Chemically inert and effectively non-emitting once fired, which makes them the cleanest class on the emissions layer and among the harshest on the acoustic one.
- Glazed porcelainVitrified clay body with a fused glass surface. Near-zero porosity, no meaningful emissions after firing.no evidence
- Unglazed and through-body porcelainVitrified body with no applied glaze, so the wear surface is the body itself and texture is intrinsic.no evidence
- Glazed ceramic and zelligePorous clay body with a glazed face, often hand-formed. Irregular geometry produces scattered rather than specular reflection at room scale.no evidence
- TerracottaLow-fired porous clay. Higher porosity, lower hardness and higher moisture uptake than porcelain, with a warmer contact response.no evidence
- GlassFused silica, used as glazing, partition, tile and screen. The only class specified primarily for what it transmits.no evidence
Metal 4
Specified in small areas and touched constantly. Thermal effusivity an order of magnitude above every other class here, which is why metal hardware is the most reliably cold thing in a room at equilibrium temperature.
- Stainless steelCorrosion-resistant steel alloy. Very high thermal effusivity, finish-dependent specularity.no evidence
- Brass and bronzeCopper alloys, commonly specified unlacquered so that the surface patinates in use.no evidence
- AluminiumLight alloy, usually anodised. High conductivity, low mass per area.no evidence
- Copper and zincReactive metals whose surfaces develop oxide layers in service.no evidence
Coatings and finishes 5
A layer measured in micrometres that determines gloss, contact response and often the entire emissions profile of the assembly beneath it. Systematically under-specified relative to its influence.
- Mineral paintSilicate or lime-based coating that bonds chemically to mineral substrates. Vapour open, matte, no film-forming polymer.no evidence
- Water-based acrylic paintThe interior default. Emissions vary by an order of magnitude between formulations sold under the same low-VOC description.no evidence
- Alkyd and solvent-based paintOil-modified resin coating. Harder film, higher gloss range, substantially higher solvent emission during cure.no evidence
- Natural oil and waxPenetrating finish that leaves the substrate texture and thermal behaviour largely intact rather than forming a film over it.no evidence
- Lacquer and UV-cured coatingFilm-forming clear coat. Changes gloss, hardness and contact response of whatever it covers.no evidence
Acoustic and insulation cores 5
Materials specified for a single measured property and almost never seen or touched. Included because they are where a room's acoustic behaviour is actually decided, behind whatever finish is credited for it.
- Mineral woolSpun stone or slag fibre. The reference porous absorber, with absorption governed by thickness, density and airflow resistivity.no evidence
- Glass woolSpun glass fibre. Similar absorption behaviour to mineral wool at lower density.no evidence
- Wood fibre boardCompressed wood fibre used as insulation and as an acoustic core. Higher density and heat capacity than mineral fibre.no evidence
- PET acoustic feltNeedle-punched polyester board, usually recycled, used as an exposed acoustic finish.no evidence
- Melamine and open-cell foamOpen-cell polymer foam used where a very light, high-absorption core is needed.no evidence