TAL-L Material Categories
The general material category describes the dominant material component of each sample within the library/database. In some cases, a sample is made of several material components and may be listed in two categories.
Animal/Animal-based
A material that is derived from or includes any byproduct or part of an animal’s body. ‘Animal’ includes any member of the animalia kingdom. Silk is an animal-based material derived from the byproduct of a silkworm cocoon. Some forms of lime are produced from oyster shells.
Carbon-based
Carbon is an abundant element (C) that can take on many forms. Diamonds and graphite are typical carbon materials. So are many nanomaterials with often outstanding physical or mechanical properties.
Cement-based
A material based on a mix of pulverized limestone and clay. Concrete and mortars are cement based. Fly ash products may replace portland cement in some cement-based products which are part of this category.
Ceramic
A fired, heat-resistant material often made of clay that may or may not be glazed. Clay bricks are ceramics. So are most building tiles.
Composite
A material made of two or more components, with the individual components no longer distinguishable. Papier-mâché is a composite material. Reinforced concrete is not.
Glass
An amorphous material made mostly of silica (i.e. quartz) derived from sand. Glass may be floated into flat sheets or cast into custom shapes. Decorative glasses are often blown or mould-blown.
Metal
A metal element or an alloy (combination) of metals and other components. Aluminium is a metal element though it is usually found in alloyed form. Steel is a metal alloy of iron, carbon and other elements.
Mineral/Mineral-based
An inorganic crystalline material that has been formed through a geological process. Rock such as granite, sandstone and marble are mineral materials. So is sulfur.
Naturals (others)
Animals, plants, soils and woods are natural materials, but have their own categories within TAL-L. Other natural materials are for example mycelium or algae.
Plant/Plant based
A material that is derived from or includes any part of a plant, with the exception of wood, which has its own category within TAL-L. ‘Plant’ includes any species of the plantae kingdom. Hemp fiber is a plant based material. So is linoleum.
Plastiglomerate
A material that binds sedimentary and other natural material components within a plastic matrix. At TAL-L, we believe this category must be considered in future.
Polymer
A natural or synthetic material with long molecular structure. Nylon is a synthetic polymer. Potato starch is a natural polymer.
Soil/Soil-based (organic/mineral)
A material extracted from the pedosphere consisting of decomposed rock (mineral) with or without organic matter. Beach sand is a soil material. So is rammed-earth.
Wood/Wood-based
A structural material from stems/branches and roots of trees and other woody plants. Oak planks are wood, but bamboo is not, as it is classified as an herbaceous plant.
Site
Site-driven materials record the specific conditions found at the point of extraction. Many materials are impacted by climate, ground condition, land use, topography, or the geology of the parent material. The detailed documentation helps to understand and potentially use a site-driven material to its full potential.
Source
Source-driven materials record information about their origin, but different from site-driven materials, those would consider information provided by a supplier about a material that was imported. The origin of a material is useful in determining its environmental impact as asked in many leading standards for climate positive material selection. At TAL-L we go beyond current standards and try to research and document as many ecological and production related attributes as possible.
Classification
Classification-driven materials record information about specific or outstanding forms and properties. To define a material by for example determining it to be a membrane with a specific surface texture helps to identify and respond to design problems.
Attribute
Attribute-driven materials record information about specific physical or chemical properties. To define a material by for example determining its soil pH or thermal expansion helps to identify and respond to performance problems.
Process
Process-driven materials are determined by their fabrication methodology. Whether hand-crafted, using CNC technologies or robotic processes, it is important for the design process to understand and evaluate how a material is manipulated.
Observation
Observation-driven materials are determined by sensory and visual qualities that can be documented without the help of specific scientific equipment. In design practice, these tactile qualities matter and must be valued in balance with more quantitative parameters such as those considered for example in the attribute-driven track.
Casting
Made by pouring a material in its liquid form into a mould. Metals are cast under high temperatures and solidify when cooling. Other casting materials such as resin or plaster harden through chemical reaction.
Filling
Made by filling an existing cavity or depression. Cementitious grouting is often used to fill the gaps between tiles. Resins are often fillers to airtight joints between two materials.
Finishing
Made by, often decoratively, alternating a surface appearance. Polishing is a mechanical finishing process that can be performed without additional materials. Coating or varnishing are finishing processes applying often liquid materials to an objects’ surface.
Forming
Made by modelling a material into a specific shape. Pottery is a forming process. To compress earth into a formwork (rammed earth) is also considered forming. 3D printing is a digital forming process.
Joining
Made by connecting two or more parts of one or different materials (see also joint). Soldering or welding are joining processes. So are knitting or weaving.
Machining
Made by cutting a material into shape. Machining processes remove material - they are subtractive. Laser cutting or CNC milling are digital machining processes. Crushing a material into finer components is a mechanical machining process.
Touch
A tactile quality that can be determined by pressing on a material. Hard materials cannot be manipulated by manual pressure. Metals are often hard materials. Firm materials are unyielding but may be slightly deformed, like for example non-fired earth bricks. Soft materials can be deforemed easily, like for example rubber.
Tactile Warmth
A tactile quality that can be determined by manually identifying a material’s surface temperature. Cool materials feel significantly colder than our body when touching at room temperature, for example glass. Tempered materials feel slightly colder, for example most polymers. Warm materials suggest no or little difference to our body temperature, like for example wood or most cotton fabrics.
Flexibility
A tactile quality that can be determined by bending a material. Flexible materials transform easily without bending, for example PVC is a flexible plastic. Semi-rigid materials are solid but not inflexible, for example asphalt. Stiff materials are inflexible to manual influence, for example….
Resilience
A material’s performance under deformation. A brittle material is prone to breaking, for example glass. A resilient material shows deformation but doesn’t fracture, for example rubber. A ductile material can be deformed without losing toughness, for example steel.
Odor
A material’s distinctive smell. Aluminum is odorless. Plywood often still has a moderate pleasant odor of cut wood. The odor of a durian is referred to as a strong unpleasant smell.
Glossiness
An optical property indicating the surface reflection of a material. A glossy material has a shiny surface with specular reflection, for example a mirror. A satin material has a smooth finish with some reflection, for example brushed metal surfaces. A matte material has a diffuse reflection, for example plaster.
Transparency
An optical quality that indicates the amount of light passing through a material. A transparent material like clear glass allows light to pass through without scattering. A translucent material allows light to pass with some scattering. Translucent glass can be achieved through frosting. An opaque material does not allow light to pass.
Munsell color for soils
Munsell color standards are commonly used to categorize soil colors. The Munsell color chart considers three attributes: hue, value, and chroma (HVC). Hue is the color, referred to by letter codes, for example YR stands for yellow-red. Value refers to the lightness or darkness, for example 2 is darker than 5. Chroma refers to how pure a color is, for example 2 is less saturated than 5.
State
State is considered as material attribute but must be specified for classification-, attribute-, process-, and observation-driven materials.
Object / Composite
An object is defined as a physical item with a functionality beyond being a material sample, for example a brick. A composite is an object consisting of more than one material, for example bamboo strips connected with an adhesive.
Solid
A solid is defined as being three dimensional and stable in shape. Most material samples in TAL-L are solids.
Liquid
A liquid is defined as a freely flowing substance. Coatings or paint samples may be recorded as liquids.
Gas
A gas is defined as a material with no fixed shape. At TAL-L, we are unlikely to archive gases but they are important for some material processes.
State
State is considered as material attribute but must be specified for classification-, attribute-, process-, and observation-driven materials.
pH Value
The pH value expresses the acidity or alkalinity of a substance. It is an important characteristic to classify soils as it affects for example the availability of plant nutrients. The pH value can be determined using a test strip. A pH value of 7 is neutral, with lower indicating acid soils, and higher indicating alkaline soil. Depending on organic content, desirable soil pH can range between 5.0 to 7.0.
Nitrate
Plants use nitrate as food, and to create their own amino acids for protein synthesis. Good nitrate levels in soils to grow productive plants are around 25 ppm.
Phosphorus
Phosphorus is important for plant growth and reproductive processes. Values of around 30 ppm are desirable to promote growth for most field crops.
Sulfate
After NPK (nitrogen - N, phosphorus - P, and potassium - K), sulfur is an essential element for plant growth and is available to plants primarily as sulfate. It is easily leached and is deficient in sandy or light-textured soils with high rates of water penetration.
Zinc
Zinc is a micronutrient important in metabolic functions such as the production of chlorophyll. Zinc is often present or deficient as a result of parent geology. Normal zinc levels are between 3-6 ppm.
Iron
Iron is widely present in soils, but not often in a form available to plants. Levels of 20-30 ppm are sufficient for available iron. As with other metallic trace elements, iron availability is influenced by pH. Iron oxides greatly influence soil color, often imparting a yellow, red or brown coloration.
Manganese
Manganese is an important micronutrient for plant growth and sustaining metabolic function, with ideal levels in soil between 20-30 ppm. Manganese can impart a black, grey or green color to soils.
Copper
Copper is important in soils for plant growth and reproduction, though in excess copper is toxic. Copper levels should range between 1-2 ppm. High organic matter or sandy soils are often deficient in the element.
Potassium
Potassium contributes to root health and reproductive processes, while also helping plants tolerate environmental stress and diseases. Potassium can be found in large quantities in soils locked in various minerals. Depending on soil type, ideal Potassium values range from 100-250 ppm.
Calcium
Calcium is widely available in soil and found in various minerals. It is an important macronutrient and plays a role in the physical and chemical properties of soil, with high calcium creating porous structure and neutral pH. Calcium rich soils tend to be whitish.
Sodium
Although not a nutrient, sodium is an important factor in soil structure and health. Sodium rich soils can become impermeable. High sodium levels in soils often result from excessive pesticide, fertilizers, and other soil additives.
Magnesium
An important soil macronutrient, and important in the photosynthetic process, ideal magnesium levels should be around 60 ppm. Magnesium is often associated with clayey soils and in excess can cause clay soils to become compacted. Magnesium carbonates can impart a white color to soil.
Density
Density is the amount of mass per unit volume and measured in kilogram per meter cubed (kg/m3). Platinum is very dense, styrofoam is not.
Tensile strength
Tensile strength is the maximum stress a material can withstand being stretched before breaking. It is important to determine the tensile strength for brittle materials, for example ceramics.
Compression strength
Compression strength is the maximum stress a material can withstand under load before breaking. The compressive strength of porcelain is very high, the one of styrofoam very low.
Thermal expansion
Thermal expansion is a material's deformation under temperature change. The deformation may influence a material's shape, area, volume or density.
Moisture content
The moisture content measures the percentage of water in a material. It is commonly determined working with natural materials such as wood and soil. A moisture meter may be used as on-site equipment.
Location of Sample extraction
Density is the amount of mass per unit volume and measured in kilogram per meter cubed (kg/m3). Platinum is very dense, styrofoam is not.
Depth of Sample extraction
Tensile strength is the maximum stress a material can withstand being stretched before breaking. It is important to determine the tensile strength for brittle materials, for example ceramics.
Slope at extraction point
Compression strength is the maximum stress a material can withstand under load before breaking. The compressive strength of porcelain is very high, the one of styrofoam very low.
Land use at extraction point
Many parameters of a site-driven material’s qualities are impacted by the current or former land use on site. The categories to determine land use are loosely based on the Hong Kong Planning Department’s classes.
Land use at extraction point
Many parameters of a site-driven material’s qualities are impacted by the current or former land use on site. The categories to determine land use are loosely based on the Hong Kong Planning Department’s classes.
Instance: residential/commercial lot
Land use at extraction point
Many parameters of a site-driven material’s qualities are impacted by the current or former land use on site. The categories to determine land use are loosely based on the Hong Kong Planning Department’s classes.
Instance: industrial lot
Land use at extraction point
Many parameters of a site-driven material’s qualities are impacted by the current or former land use on site. The categories to determine land use are loosely based on the Hong Kong Planning Department’s classes.
Instance: open space
Land use at extraction point
Many parameters of a site-driven material’s qualities are impacted by the current or former land use on site. The categories to determine land use are loosely based on the Hong Kong Planning Department’s classes.
Instance: roads/transport
Land use at extraction point
Many parameters of a site-driven material’s qualities are impacted by the current or former land use on site. The categories to determine land use are loosely based on the Hong Kong Planning Department’s classes.
Instance: airport facilities
Land use at extraction point
Many parameters of a site-driven material’s qualities are impacted by the current or former land use on site. The categories to determine land use are loosely based on the Hong Kong Planning Department’s classes.
Instance: port facilities
Land use at extraction point
Many parameters of a site-driven material’s qualities are impacted by the current or former land use on site. The categories to determine land use are loosely based on the Hong Kong Planning Department’s classes.
Instance: cemeteries
Land use at extraction point
Many parameters of a site-driven material’s qualities are impacted by the current or former land use on site. The categories to determine land use are loosely based on the Hong Kong Planning Department’s classes.
Instance: urban utilities
Land use at extraction point
Many parameters of a site-driven material’s qualities are impacted by the current or former land use on site. The categories to determine land use are loosely based on the Hong Kong Planning Department’s classes.
Instance: vacant land/construction
Land use at extraction point
Many parameters of a site-driven material’s qualities are impacted by the current or former land use on site. The categories to determine land use are loosely based on the Hong Kong Planning Department’s classes.
Instance: agricultural land
Land use at extraction point
Many parameters of a site-driven material’s qualities are impacted by the current or former land use on site. The categories to determine land use are loosely based on the Hong Kong Planning Department’s classes.
Instance: fish ponds
Land use at extraction point
Many parameters of a site-driven material’s qualities are impacted by the current or former land use on site. The categories to determine land use are loosely based on the Hong Kong Planning Department’s classes.
Instance: shrubland
Land use at extraction point
Many parameters of a site-driven material’s qualities are impacted by the current or former land use on site. The categories to determine land use are loosely based on the Hong Kong Planning Department’s classes.
Instance: woodland
Land use at extraction point
Many parameters of a site-driven material’s qualities are impacted by the current or former land use on site. The categories to determine land use are loosely based on the Hong Kong Planning Department’s classes.
Instance: grassland
Land use at extraction point
Many parameters of a site-driven material’s qualities are impacted by the current or former land use on site. The categories to determine land use are loosely based on the Hong Kong Planning Department’s classes.
Instance: mangrove
Land use at extraction point
Many parameters of a site-driven material’s qualities are impacted by the current or former land use on site. The categories to determine land use are loosely based on the Hong Kong Planning Department’s classes.
Instance: badland
Land use at extraction point
Many parameters of a site-driven material’s qualities are impacted by the current or former land use on site. The categories to determine land use are loosely based on the Hong Kong Planning Department’s classes.
Instance: rocky shore
Land use at extraction point
Many parameters of a site-driven material’s qualities are impacted by the current or former land use on site. The categories to determine land use are loosely based on the Hong Kong Planning Department’s classes.
Instance: reservoir
Land use at extraction point
Many parameters of a site-driven material’s qualities are impacted by the current or former land use on site. The categories to determine land use are loosely based on the Hong Kong Planning Department’s classes.
Instance: streams
Land use at extraction point
Many parameters of a site-driven material’s qualities are impacted by the current or former land use on site. The categories to determine land use are loosely based on the Hong Kong Planning Department’s classes.
Instance: beach
Surface condition (for soil materials only)
Many soil surfaces have a characteristic appearance when dry. The main forms of surface condition are:
Cracking - There are cracks at least 5mm wide when the soil is dry. Cracking is usually associated with clayey surfaced soils.
Self-mulching - The soil surface forms many small loose peds on drying. Self-mulching is usually associated with clayey surfaced soils.
Loose - The soil particles are separate. For example, sand has a loose surface condition.
Hardsetting - The surface becomes compact and hard upon drying.
Geology of parent material (for soil materials only)
The geology of parent material is specified with reference to the Solid and Superficial Geology Map (1:20,000) by the Geotechnical Engineering Office.
Natural or imported material
All site- and source-driven materials must record whether the material is natural to a site/local to Hong Kong or it is imported. A site-driven material such as topsoil might consist of different soil components which are sourced and mixed off-site before being implemented on a landscape project. A source-driven material such as a stone may be quarried far away from the destination site. If known, this information should be recorded. If it is unclear whether a material is natural or imported, ‘unknown’ may be selected.
Recycling percentage
The recycling percentage specifies the volume of the material which can be recycled or reused again in a similar application. For example, glass is not considered recyclable even though it may be reused in terrazzo materials or similar creative downcycling projects. Rammed earth with no cement-based additives, although, has a recycling percentage of 100%.
Reclaimed components
Reclaimed components define the amount of material being reused in the material’s composition. For example, crushed glass used in terrazzo material is a reclaimed component. Recycled paper would be considered to be composed of 100% reclaimed material.
Expected life span
The expected life span refers to a material’s intended application. The same material may have different life spans depending on the climate it is used in. If not specified differently in TAL-L, we assume a material is used outdoors in the Hong Kong climate. We also assume that a material is regularly maintained as specified by the producer.
Recycling potential
The recycling potential considers environmental and economic factors of a material’s life cycle. For example, paper and cardboard have a high recycling potential because of the little energy consumption and cost during the recycling process. Metals are also easy to recycle, however, especially metal alloys have a medium to low recycling potential due to the complicated process needed to break them down into their elements to be reused.
Degradation
The time taken for a material to degrade as part of a natural aging process through exposure to the environment. A material is considered ‘degraded’ when it is no longer fulfilling its original application requirements. These requirements can be physical or visual. For example, a dyed polymer may lose its color due to UV exposure after 2 years. A solid stone may not change its appearance (under regular maintenance) for more than 50 years.
CO2 Footprint
The CO2 footprint refers to the total amount of greenhouse gasses caused by a material. This includes the extraction and processing of raw materials, fabrication and transportation. Cement has a high CO2 footprint. The CO2 footprint of local timber is low.
Collateral pollution
The release of harmful contaminants into the environment - air, water, or land - during the production process of a material. The quarrying of limestone for cement production causes air pollution. Many dyes used in the textile industry cause water pollution.
Water for production
Many industrial production processes require large amounts of water. Steel production uses significant amounts of water in cooling processes. In cement production, large amounts of water are required for washing and crushing the limestone.
Production Energy
The energy required to produce a material from its raw to finished form includes extraction, processing, and manufacturing energy. Aluminum has a high embodied production energy. The production energy for bricks is relatively low.
Distance from Source Location
The distance between the location of the production/extraction site of a material and its destination location. If a material is extracted and produced in two different locations, the distance can be added.
Form
The form of a material can be described with up to three different items. Classification driven materials must specify at least one form.
Additive
A substance that is added to or or has the potential to be added to another material. Plasticizers are an additive to increase the workability of concrete.
Adhesive
A substance that has the capability to bind materials or hold material components together. Glue or cement are adhesives.
Block
A solid piece made of one consistent material or material mix. Bricks or marble slabs are blocks.
Aggregate
A material consisting of loosely compacted fragments or particles. Aggregates can be components of material mixtures, for example sand is an aggregate for concrete.
Coating
A usually liquid material that is applied onto the surface of another material. Paints are coatings. So are glazes on ceramics.
Emulsion
A mixture of at least two liquid materials that are unblendable, for example water and oil.
Extrusion
A process to shape materials with a predefined cross-section through a die. HDPE pipes are extrusions. So are standard aluminum profiles.
Fabric/Textile
A fibrous material that is shaped through a process of interlacing, for example weaving or knitting. Geomembranes are fabrics. So are carpets.
Fiber
A natural or synthetic material (component) that is longer than wide. Flax is natural fiber to produce linen. Nylon are synthetic fibers.
Filament
A continuous thread. PLA filament is commonly used for 3D printing. A filament made of a tin and lead alloy is often used for soldering.
Filling (Filler)
A soft material used to fill a void/gap within another material. Grouting is a filling material to seal gaps between tiles.
Foam
A solid material with gas (often air) pockets. Natural or synthetic sponges are foams. Polystyrene may be foamed (expanded).
Joint
A point where two or more parts of one or different materials meet. A hinge is a moveable joint to connect two objects. An expansion joint creates allowance for thermal expansion between two components of the same material.
Membrane
A thin pliable sheet of material. Membranes can act as filters for gases or liquids. PVC membranes can create tensile structures.
Mesh
An interlaced structure of threads or wires. Wire meshes are commonly used as fences. Jute meshes are commonly used to control erosion on sloped terrain.
Netting (Net)
Similar to meshes. But nets, usually consisting of yarns or threads, are knotted or fused at their intersections.
Particulate (Particle)
Tiny components of solid or liquid matter suspended in the air. Dust is made of earth and waste particles.
Plate
A flat thin piece of material. Steel plates are often used to strengthen foundations. A circular plate of glazed ceramic may be used as dishware.
Powder
A material made of dry particles. Clay exists in powder form. Ground coffee is a powder as well.
Pulp
A natural fibrous material. Paper is traditionally made of wood pulp mixed with water. Pulp can also be made of straw, reed or bamboo.
Rope
A strong material made of twisted yarns, fibers, or strands. Natural ropes can be made of sisal. Synthetic ropes can be made of Polypropylene.
Sheet
A flat piece of material that can be cut and formed. Paper, wood, metal, or textiles can be sheet materials.
Shell
A thin material shaped into a 3 dimensional geometry. Eggs have shells. Parabolic shell vaults are structures that can span large distances.
Slab
A thick flat piece of material. Floor slabs of buildings are often made of cast concrete. A stone slab can for example be used for paving or as wall cladding.
Tiling (Tile)
A thin slab material. Tiles can be made of fired clay. Slate tiles can be used for roofing.
Veneer
A thin usually solid material that is applied onto another material. Wood veneers are often decorative. Plastic veneers can also protect the base material for instance from humidity.
Wire
A flexible strand or rod of metal. Electrical cables are wires.
Wrap
A covering, usually soft, that encloses another material. Vinyl is used to wrap glass. Felt asphalt is used to wrap roof structures as protection from the elements.
Properties
The properties of a material can be described with up to three different items. Classification-driven materials must specify at least one property.
Aerobic
Requiring oxygen for growth or transformation. Microorganisms used for composting require oxygen. Many bioplastics deteriorate due to aerobic processes.
Amorphous
Not having a clearly defined form or shape, non-crystalline. Silicone is amorphous. So is sand.
Anaerobic
Requiring the absence of oxygen to transform. Some adhesives only cure in the absence of air. Fermentation is a process of anaerobic digestion.
Anti-bacterial
Obstructing the growth of microorganisms. Copper has antibacterial properties. The surface of textiles is sometimes physically modified to improve their antibacterial properties.
Anti-scratch
Preventing small surface-level cuts. Materials with anti-scratch properties are usually applied as a protective coating or film.
Anti-slip
Preventing slipping, usually on a flooring surface. Tiles may have surfaces to increase friction (anti-skid). Floorings may be specified with slip ratings between R9 (lowest) and R13 (highest).
Anti-static
Preventing the buildup of static electricity. Some polymers have anti-static properties. Coatings with anti-static properties can be applied to materials which tend to prevent static charge.
Brushed
Roughening a surface texture. Metal may be brushed to generate a non-reflective surface.
Chromed
Treating or plating a surface with chromium. Metals can be chromed for decorative applications, to harden the surface or to prevent corrosion.
Coarse
Irregularly textured or made of large particles. A coarse soil indicates a high proportion of sand. A jute fabric has a coarse texture.
Coated
With another material applied to the surface. (see Coating)
Corrugated
Shaped with parallel grooves. For example cardboard or metal may be corrugated to increase rigidity.
Dyed
Coloured in a way that penetrates the surface, usually by using a liquid substance. Cotton is often dyed with indigo, a natural dye made of leaves. Oxide-based pigments may be used to dye bricks.
Edible
Suitable to be consumed by humans. Sticky rice may be used as a component to increase binding force in rammed earth construction. Mycelium is edible as well as a building material with growing influence.
Elastic
Flexible or adaptable with the ability to spontaneously resume its shape. A rubber band is elastic. Metal can be elastic if formed into a helical metal coil (spring).
Etched
Subtracting from/cutting into a hard material surface. Traditionally, acid is used to etch metal. Lasers may also be used to etch material surfaces.
Extruded
Shaped through a die. (see Extrusion)
Fluorescent
Producing visible light, a form of luminescence. Some microalgae glow when touching sea water. Some minerals have fluorescent properties under ultraviolet light.
Folded
Forming a crease by bending. For example, metal or paper can be folded.
Galvanized
Coated with zinc. Iron or steel can be galvanized to protect its surface.
Heat-resistant
Protecting a material from acquiring too high temperatures. Ceramics are heat-resistant. Specific coatings may insulate less heat-resistant materials like fabrics.
Honed
Finished to an even and smooth but non-reflective surface. Stone can be honed. Frosted glass may be referred to as honed glass.
Magnetic
A physical property that attracts a material strongly to magnetic fields. Iron is a ferromagnetic material. Graphite is magnetic at room temperature.
Oxidized
Chemically transforming by obtaining electrons from a material’s surface. Water and air can cause oxidation to metals. Oxidation can be accelerated by chemical processes, for instance to provide a protective rust layer for weathering steel.
Permeable
As porous material allowing liquids or gases to pass through. Gravel is permeable, granite pavers are not.
Porous
Having interstices or voids. Sponges are porous. So are for example some volcanic rocks.
Reinforced
Strengthened through the inclusion of an additional material. Concrete may be reinforced with steel or fiberglass.
Textured
With a rough or uneven but consistent surface. Textures may be created by repeated processes, such as the weaving of fabrics. Different aggregates in the mortar mix may influence the texture of rendered walls.
Tinted
Slightly coloured. Glass may be tinted by adding small amounts of metal oxide to influence light transmission. Wood may be tinted by applying varnish.
UV Resistant
Defying degradation through exposure to ultraviolet light. Acrylic is UV resistant. Some fabrics, such as cotton, may absorb some UV radiation but are not UV resistant.
Washable
Cleanable in water without damage. Many fabrics are washable. Many reclaimed materials require washing before being reused.
Waterproof
Impervious to water penetration. A synthetic waterproofing material is polyurethane, a natural one is rubber.
Woven
Formed by interlacing threads. Most fabrics are woven. Bamboo, rattan or metal can also be woven into sheet materials or shell-like structures.
Lab
Lab is the pedagogical framework and set of tools that facilitate material testing and experimentation.
Archive
Archive is the body of material samples and their acquisition structure.
Taxon
Taxon is the classification structure that connects materials-based enquiry to the broader landscape architecture curriculum.