Sarah Clarity Studios

Chapter 1: Wood, Stone, Metal, Concrete, Glass, Fabric

Created by Sarah Choi (prompt writer using ChatGPT)

Wood, Stone, Metal, Concrete, Glass, Fabric — Material Systems, Aging, and Weathering for Environment Concept Artists

Why materials tell the truth of a place

Form gives a scene its silhouette, but materials carry its time, climate, labor, and care. A plank’s end grain, a mortar joint’s thickness, a rust halo under a bolt, a lime run beneath a coping stone—each is a small forensic clue. When you understand how materials are made, assembled, finished, and then slowly unmade by weather and use, you can design convincing spaces in concept and translate them into resilient, performant assets in production. Think of this guide as a field manual: how to read matter, how to paint its life cycle, and how to encode that logic into your pipeline.

Wood: anatomy, fabrication, finishes, and weathering

Wood is a cellular composite with strong directionality. Grain parallel to length carries tension and bending; across grain, strength and dimensional stability drop. Softwoods (conifers) mill into long, straight members with visible growth rings and fewer pores; hardwoods vary widely in figure and density. End grain drinks finish and water like a bundle of straws; face grain is more stable; edge grain sits between. Joinery and fasteners exploit this anisotropy: mortise‑and‑tenon, scarf joints, dovetails, and modern screws or bolts place forces along grain where possible.

Fresh wood moves with moisture. Boards cup toward the bark side, check at ends as they dry, and shrink more tangentially than radially. Exterior exposure silvers lignin at the surface under UV, raising soft springwood and leaving hard latewood ridges. South‑ and west‑facing elevations bleach and crack faster; north faces grow algae, moss, and mildew. Water entry at joints produces dark halos around fasteners and black iron/tannin stains in oak and cedar. Paint fails first at sharp arrises and end grain; oils and tars deepen color and slow moisture swings but capture dust. In wet‑dry cycles, decking wears into footfall channels; rail tops polish, while underside edges keep original saw marks. In cold climates, freeze–thaw in checks pries fibers apart; in hot desert, fibers split along rays; in tropical belts, fungi and insects colonize unprotected sapwood.

In concept, choose species archetypes to drive palette and figure: pale, straight softwood for scaffolds and industrial framing, warm ring‑porous hardwood for interiors with visible rays, resinous cedar for exterior shingles with varied tone. In production, align normal detail with grain direction; bias roughness by wear so handrails read glossier on the upper arc and matte on vertical faces; push AO along board gaps and under laps; add dark, diffuse stains beneath fasteners and at drip lines. Edge wear should expose brighter, freshly cut wood where recent work occurred; older edges soften and gray. Snow and rain accumulate on horizontal faces; dust collects on top of sills and beams beneath skylights; lichen colonizes the cool, shaded side.

Stone: geology in construction, cutting, bedding, and decay

Stone is strength in compression and, depending on lithology, weakness along bedding or joints. Sedimentary stones like limestone, sandstone, and shale preserve layers and sometimes fossils; bedding orientation matters—set with bed for durability in ashlar, never on edge for lintels unless the stone is massive and isotropic. Metamorphic stones like slate and schist cleave along foliation, excellent for roofing and thin veneers but vulnerable to delamination where water intrudes. Igneous stones split between crystalline granites and basalts, which take crisp arrises and resist weather, and vesicular lavas and tuffs, which are lighter, more porous, and decay unevenly.

Tooling leaves signature surfaces: quarry drag lines on split faces, pitched arrises on ashlar, tooth‑chisel chatter on dressed blocks, saw kerf striations on modern cuts. Lime mortars breathe and erode at joints, leaving recessed, soft edges; cement mortars keep joints proud and can trap moisture, spalling adjacent stone. In marine air, salt crystallization exfoliates faces; in polluted air, gypsum crusts form under sheltered drip edges; in freeze climates, microcracks at edges enlarge and corners round. Biological colonization begins with algae films, then lichens and moss; roots exploit joints and force open bedding planes. Iron inclusions bleed orange tears; copper roofs above leave green streaks; tar and soot embed in rough textures.

In concept, assign lithology to set hue and behavior: honey limestone with soft arrises in a temperate town, iron‑red sandstone with dark varnish in arid cliffs, blue‑gray slate on steep wet roofs. Respect coursing and bond patterns; turn corners with true through‑stones or express quoin blocks. In production, map micro‑normal frequency to tool finish, use cavity masks to place soot and salt, and let wetness rise from base courses by capillarity. Keep drip edges lighter where water cleans; add darker skirts where splash strikes; vary block tone by quarry lot and repair era. Cracks propagate from loaded openings toward corners; patch stones and Dutchman repairs shift color subtly and sharpen arrises locally.

Metal: ferrous and non‑ferrous systems, coatings, corrosion, and repair

Metals read as intent and precision, then slowly confess their chemistry. Ferrous alloys—cast iron, wrought iron, and steels—range from brittle compression members with flake graphite to ductile, weldable frames. Non‑ferrous metals—copper, bronze, brass, aluminum, zinc—oxidize into characteristic patinas. Surface finish and protection decide the pace of change. Galvanization sacrifices zinc to protect steel, leaving matte spangle under paint or as bare silver that dulls to gray. Powder coats form tough color films but chip at edges and hardware. Mill scale on hot‑rolled steel begins as a blue‑black sheen; if scratched, rust nucleates at breaks and creeps beneath coatings. Stainless forms passive chromium oxide layers but tea‑stains in salt air where crevices trap chlorides.

Corrosion follows physics and detailing. Water and oxygen access, galvanic couples between dissimilar metals, and crevices at lap joints drive failure. Fasteners become sacrificial points when paired poorly; bolts leave ring rusts, and streaks trail from every drip edge. On copper and brass, oxide blooms from brown to black to green in moisture and marine air; runoff paints stone below with green tears. Aluminum pits in salty spray, especially at unpainted edges; bare zinc chalks; lead dulls to gray with white carbonate blooms under acid rain. Heat stains near welds and exhausts mark industrial life—straw yellow through blue on stainless, dull gray on carbon steel.

In concept, choose metal families to set tone and age: riveted iron trusses with orange runs for 19th‑century bridges, weathering steel plates with controlled rust bands for contemporary infrastructure, burnished brass and bronze for ceremonial interiors, oxidized copper for civic domes. In production, drive curvature‑ and cavity‑based masks to place rust, streaks, and chalking; add subtle edge brightening on guard rails and ladders from hand contact; vary roughness where paint has worn to primer on step treads; animate moisture beads and drip lines beneath handrails in rain. Keep bolted connections legible; express splice plates and gussets; let galvanic logic decide where the worst staining happens.

Concrete: mix, reinforcement, formwork memory, cracking, and staining

Concrete is stone poured into memory. Mix design, placement, compaction, curing, and formwork all write into the surface. Board‑formed work retains wood grain and tie hole rhythm; steel forms leave smooth planes with regular cone marks; slip‑formed cores show lift joints and cold seams. Reinforcement patterns govern crack maps—flexural cracks vertical at mid‑span, diagonal shear cracks near supports, shrinkage hairlines at reentrant corners. Where cover is thin or detailing poor, carbonation and chlorides reach rebar; rust expands and spalls the face, exposing steel with orange halos.

Water is concrete’s storyteller. Leaks at joints and parapets etch lime runs; efflorescence powders under sheltered edges; algae greens appear where drips persist; dirty skirts rise from splash zones; freeze–thaw scales surfaces at ponding spots. Thermal movement opens joints; poorly handled penetrations weep rust. Repairs arrive as patches with different aggregate and color; epoxy crack injections leave neat stitch marks; FRP wraps change sheen. Exposed aggregate and terrazzo bring different wear—high points polish; binders dull; dividers collect grime.

In concept, select finish archetypes: heroic board‑form with deep grain for brutalist dams or vaults, smooth architectural precast with crisp arrises for civic plinths, rough cast for utility piers. In production, bake tie‑hole arrays and lift seams into masks for wetness and streak placement; modulate roughness and AO by formwork imprint; create age states from fresh gray to warm buff to soot‑stained; align crack decals to stress logic rather than random scatter. Where vegetation meets concrete, let roots lift slabs and moss trail along joints; where metal meets concrete, add rust blooms and mineral aprons below anchors.

Glass: optics, assembly, failure, and contamination

Glass is both surface and volume. Its read depends on refractive index, coatings, thickness, and sky. Old crown and cylinder glass waves and seeds reflect in rippled, distorted images; modern float glass is optically true until coated. Low‑E and solar control coatings shift color at angles—blue‑green or bronze—while double and triple glazing create secondary reflections. Unitized curtain walls repeat mullion modules and gasket shadows; stick systems show joints and pressure plates; structural glazing conceals metal and emphasizes edge frits. Laminated panes spider‑web under impact and remain in place; tempered panes shatter into pebbles; heat‑strengthened glass holds cracks in larger islands. Sealant failure clouds IGU cavities with moisture; nickel sulfide inclusions cause spontaneous breakage in rare cases.

Contamination collects in predictable halos. Hard water leaves mineral arcs at sills; wipers paint crescents; run‑in grime accumulates at drip edges; bird strikes print dust ghosts; coastal spray etches over time; urban soot films the leeward faces near traffic. Interior condensation writes seasonal arcs on cold mornings; smokers’ films yellow historic windows. Broken panes shed shards differently depending on support—glazing points in putty leave irregular breaks; structural silicone leaves clean edges.

In concept, set glass family by era and program: small‑pane timber sash with wavy reflections for historic streets, steel‑mullion industrial lights with wired glass in factories, tall low‑iron laminated sheets at galleries with green‑edged stacks, double‑skin facades with venetian blinds shimmering in the cavity for offices. In production, tune reflection color by angle; add a second environment for interior read; bias roughness and dirt to edges and low‑flow zones; place streaks beneath top caps and under failed weeps. Show fasteners where glass meets structure: toggle clips, pressure plates, spiders. At night, interiors override reflections; LEDs stripe mullion bays; blinds stagger at human rhythms.

Fabric: from tents to sails and soft infrastructure

Textiles stretch, sag, stain, and flutter, turning wind into motion and weather into patina. Natural fibers like cotton, hemp, wool, and canvas swell when wet and mildew when stored damp; synthetics like polyester, PTFE, and PVC‑coated meshes resist rot but chalk under UV and attract dust by static. Cables and masts hold tensile membranes in anticlastic curves; seams, keder rails, and corner plates concentrate stress and collect grime. Awnings shine where handled and dull along sun‑burned ridges; market tarps patch with mismatched fabric; prayer flags fray progressively at edges; sails show crease memory and salt bloom. Wet‑dry cycles leave tide lines on festival canopies; smoke and grease spot street food tarps; condensation rains at low points in cool nights.

In concept, choose fabric archetypes for mood and climate: translucent PTFE shells glowing at night over plazas, dark waxed canvas tarps draped over yard clutter, bright awnings turning streets into shaded tunnels in the tropics, wool felt and hides at nomad camps. In production, simulate gravity and wind with coherent vectors; let seams roof and valley water correctly; drive dirt to tension lines and low points; animate edge fray and flap at gust peaks; vary wetness and translucency by rain state and sun angle.

Interactions, assemblies, and the seams between

Materials rarely act alone; their seams tell the richest stories. Flashings of metal protect wood and stone at junctions; when missing or poorly detailed, leaks stripe surfaces below and decay spreads from the seam. Sealants fail at corners; gaskets shrink; weep holes clog, and stains radiate outward. Thermal bridges betray themselves as condensation stripes on cold mornings. Fasteners imprint through thin skins; screws back out and leave rust comets. Bird deterrent spikes collect spider webs and dust; security cameras leave clean haloes behind; signage ghosts remain when businesses turn over. Expressing these interactions grounds the scene in construction reality and offers natural places for decals and VFX.

Climate scripts and exposure logic

Every region writes a different aging script. In wet temperate climates, wood silvers, moss carpets shade, and rust is steady but slow; in arid climates, paint chalks, stone varnishes, and metals redden cleanly with little biological smear; in coastal belts, salt crescendos everything—tea‑stained stainless, greened copper, pitted aluminum, spalled concrete; in cold interiors, freeze–thaw punishes pores and raises spalls on stone and concrete, while snow loads bend thin roofs and ice dams paint tar streaks. Aspect matters locally: equator‑facing walls bleach and check; pole‑facing walls stay dark and wet; windward faces polish; leeward faces collect soot; splash zones ring bases; overhangs keep crisp arrises while exposed caps round quickly. Encode exposure with masks—slope, aspect, occlusion, flow—so material states update with weather and time‑of‑day variants.

Storytelling with repair, retrofit, and maintenance

Repairs admit time honestly. Patch stones with sharper arrises and slight color shifts; infill brick with mismatched bond; sister a timber with new bolt lines; add plates and splints to metal at fatigue points; wrap concrete columns with FRP at flood‑scar height; swap panes with different coatings or tints; stitch fabric with visible zig‑zags. Retrofitted systems layer onto old bones: conduit surface‑mounted over plaster, HVAC louvers cut into stone, solar hot‑water tanks on tile roofs, external steel stairs bolted through old parapets. Maintenance culture sets mood—a tidy district repaints railings evenly and power‑washes algae; a hard‑worked yard accepts rust blooms and oil stains; a storm‑battered quay keeps sandbags stacked and ropes frayed but ready. Choose a maintenance level and iterate consistently across materials and props.

Translation to production: PBR, masks, decals, and states

Material believability improves when physics and art agree. In PBR, dielectric materials carry color in albedo and variation in roughness; metals carry color in the specular response with near‑black albedo. Keep wood and stone metallic at zero; metals at one where bare; painted metal is dielectric until chipped. Roughness is your storytelling channel: polish where hands and feet pass; increase micro‑roughness where oxidation or chalking blooms. Use world‑space masks for slope, aspect, curvature, AO, flow, and wetness to drive blends: wet darkening from the ground up during rain, dust settling on horizontal ledges in dry states, snow in cool concavities, salt crusts in marine bands. Reserve decals for high‑frequency, high‑contrast events—graffiti, cracks with displacement, drips and runs, leaf litter clumps—and keep them aligned to gravity and flow rather than wallpapered randomly.

Author age states per material: fresh, service, tired, failed. Fresh wood shows cut light ends and crisp tool marks; service shows silvering and minor checks; tired shows blackened end grain and lifted paint; failed shows rot, missing pieces, and fungus. Fresh steel shows mill scale; service shows light scratches and runoff; tired shows under‑film rust at laps; failed shows delamination and holes. Fresh concrete reads tight and even; service shows faint lines and occasional drip; tired shows efflorescence and hairline cracks; failed shows spalls and exposed rebar. Swap states by zone and scenario to tell time with minimal asset changes.

Troubleshooting common material mistakes

Uniform grime flattens scenes; aging is patchy and follows exposure, not an even overlay. Edge wear that glows everywhere looks gamey; limit brightened edges to touch zones and abrasion paths. Rust without stains below reads pasted; always pair corrosion with runoff and halo. Wood grains mapped perpendicular to boards break the illusion; align UVs or triplanar direction with geometry. Stone walls with randomized colors every block lose coursing; keep palette tight and drift by course and repair era. Glass that mirrors the sky at night ignores interiors; adjust fresnel and swap to interior emissive dominance after dark. Fabric that sags upward denies gravity; model catenaries and tension lines.

Field exercises to sharpen your eye

Walk one block in your city and catalog a single seam on each material: a flashing edge on a parapet, a rust trail from a bolt, a lime run beneath a coping stone, a paint failure on a sill, a wiper arc on a shopfront. Sketch the exposure logic and note which cues recur. Then paint a small vignette twice: once in a wet maritime palette and once in an arid, high‑sun palette, changing only masks and aging—not the base materials. The exercise trains you to tell climate and time without exposition.

Final checklist

Does every material choice match structure and climate? Do wood grains, stone bedding, metal joins, and formwork memories align with how things are built? Are aging cues driven by exposure and flow rather than random noise? Do repair patches, retrofits, and maintenance levels tell a consistent timeline? Do your PBR ranges respect physics, with roughness doing most of the narrative work? If the answers are yes, your materials will stop being wallpaper and start being evidence—of weather, work, culture, and time.