Sarah Clarity Studios

Chapter 1: Coatings & Finishes (Matte / Gloss, Anodize, Paint, Glaze)

Created by Sarah Choi (prompt writer using ChatGPT)

Coatings & Finishes — Materials & Surface Language (Wood, Metal, Plastic, Glass, Ceramic, Fabric, Rubber)

Purpose and Scope

Coatings and finishes are the last mile of believability. They control how light reads your prop, how it ages, and how the audience infers cost, care, and function. This article equips prop concept artists—on both the concepting and production sides—with practical surface language across wood, metal, plastic, glass, ceramic, fabric, and rubber. It explains how gloss and matte work physically, why an anodized part does not age like paint, how sealers and glazes affect color and roughness, and how to communicate finish intent to modeling, surfacing, and physical build teams.

Finish Fundamentals: Gloss, Matte, and Microsurface

Every finish begins with two levers: base color and microsurface. Gloss is not a color; it is the tightness of reflections. Matte surfaces scatter light with a broad lobe because their micro‑topography is rough; glossy ones reflect light in a narrow lobe because the surface is smooth. Clearcoats add a second specular layer above the pigment, creating depth and distinct highlight behavior. Anisotropy appears where microscopic grooves align, as on brushed metals or sanded lacquers, and it steers highlights into elongated streaks. In concept, decide value and gloss before hue so the prop reads at distance. In production, use roughness rather than specular color to drive most finish differences and avoid painting “fake” highlights.

Paint Systems: Primer, Color, Clear

Paint is a stack of intent. Primer grips the substrate, seals porosity, and equalizes color; color coats carry pigment and effect flakes; clearcoats provide durability and gloss control. Enamels cure into hard, glossy films suited to appliances; acrylics dry faster and chip more easily; urethanes and two‑part epoxies deliver automotive‑grade toughness. Powder coat fuses thermoset powder onto grounded metal, yielding a thick, rounded‑edge film with subtle orange peel and excellent chip resistance. In hero props, a thin, hurried overpaint reveals brush strokes, roller lap marks, and “grin‑through” at edges where donor color shows. Each paint system ages differently. Enamels chalk and fade, powder coat dents without shattering, and epoxies yellow slightly under UV. Primer halos around patches and the crispness of tape edges tell a story of maintenance practices.

Metal Finishes: Anodize, Plating, Bluing, Brushing

Metals can be finished without paint, which changes how they age. Anodizing converts the surface of aluminum into a porous oxide you can dye and then seal, producing jewel‑like translucency with a hard, abrasion‑resistant skin. It does not peel; it thins and discolors where abraded, revealing a bright aluminum under‑sheen and soft white oxidation in salt. Plating deposits a new metal layer, such as nickel, chrome, zinc, or tin. Chrome throws sharp, mirror‑like highlights and fails by pitting and flaking at edges. Nickel is warmer and slightly softer in reflectivity. Zinc and galvanizing produce mottled, crystalline patterns that dull to chalky gray and form white corrosion blooms at fasteners. Steel finishes like hot bluing or parkerizing are conversion layers that darken the surface; they wear to bright metal at corners and absorb oils into a satin sheen. Brushed or ground finishes create directional anisotropy that survives under thin clearcoats and guides highlight flow along the brush direction, helping you shape the read of cylinders and panels.

Wood Finishes: Oils, Waxes, Varnishes, Lacquers

Wood reads through its finish. Oil finishes such as linseed or tung penetrate fibers, deepen grain contrast, and cure to a low‑sheen, hand‑rubbed look that spot‑polishes where touched. Waxes overlay a soft, warm sheen that fingerprints easily and blurs reflections, suggesting craft over industry. Varnishes and polyurethanes build a thicker, protective film that bridges pores and levels into a higher gloss dependent on sanding quality; they chip around fasteners and craze with UV and heat. Nitrocellulose lacquer, common on instruments and vintage furniture, sprays thin, builds fast, and buffs to a glassy gloss; it solvent melts into previous coats and cracks in fine “finish checking” under temperature swings. Water‑borne clears run cooler in tone and can telegraph a slight plasticity. End grain drinks finish and darkens more, while open‑pore species benefit from grain filler to avoid craterlike speculars. Edge wear on wood exposes lighter raw fibers, then darkens with oils from hands, telling a useful age story.

Plastic Finishes: Mold Texture, Paint, and Coatings

Most plastics are born with a mold texture that defines their default roughness. Polished tools yield glossy housings and razor‑sharp highlights that show every scratch; light chemical etch or EDM textures produce tasteful satin; heavy pebble textures hide wear and fingerprints. Many plastics are color‑through; scuffs lighten rather than exposing a new color, and edges round rather than chip. Painted plastics introduce a separate failure mode where the paint chips to reveal the substrate. Soft‑touch coatings add a rubbery matte that reads premium but wears to glossy patches under fingers and can peel in flakes with age. UV embrittlement creates a chalky, sun‑bleached skim that powders off under touch, especially on HDPE and PP. Texture directionality from flow lines appears subtly under gloss if the part was injection molded; acknowledge or suppress it depending on your world’s level of polish.

Glass Finishes: Polish, AR Coats, Frosting, and Tint

Glass is defined by its surface flatness and index of refraction. Polished glass throws hard, accurate reflections; imperfections wave those reflections and create local distortions near edges. Anti‑reflective coatings add faint blue or purple sheens at grazing angles and reduce highlight intensity at certain view angles, which is a useful realism cue for optics. Tinted glass absorbs wavelengths and the color is most pronounced in thickness, which is why bottle lips read strongly. Frosted or acid‑etched glass scatters light, turning hard reflections into diffuse halos and obscuring internal detail while preserving silhouette. Laminated safety glass shows a greenish interlayer line and, when stressed, forms whitish, fan‑shaped patterns. Modern glass often carries screen‑printed ceramic frits as black borders with tiny dot gradients; they give specular contrast and hide adhesive zones.

Ceramic Finishes: Glaze, Slip, and Crazing

Ceramics derive color and gloss from glazes—glass‑like layers fused in the kiln. Glossy glazes create mirrorlike highlights that pool thicker at concave corners and thin over edges, shifting value subtly. Matte glazes contain crystalline phases or micro‑texture that broaden the specular and feel velvety. Underglaze decoration sits beneath a clear layer and appears optically deep. Overglaze enamels sit on top and chip first. Crazing is a network of fine cracks in the glaze from thermal or moisture mismatch; it collects grime and telegraphs age. Unglazed ceramics such as terracotta or porcelain read as porous, absorb oils readily, and darken at touch points and waterlines, giving you a grounded, earthy counterpoint to glossy industrial surfaces.

Fabric Finishes: Weave, DWR, and Coated Textiles

Fabric finish is a dance between fiber, weave, and chemical treatments. Tight weaves with filament synthetics produce crisp specular ribbing along the yarn path, while cotton or wool fuzz scatter light into a broad matte. Durable water repellent (DWR) treatments make water bead and add a faintly slick sheen that diminishes with wear, creating glossy high‑contact tracks on shoulders or knees. Polyurethane‑coated fabrics take on a plasticky luster on one side and often crack at fold lines, revealing fabric texture underneath. Waxed cotton darkens when warm, lightens when scuffed, and shows crease whiteouts like paper, a beautiful storytelling finish for field gear. Heat‑set pleats or ripstop grids introduce repeating micro‑reads that help camera scale and can be exploited as mid‑frequency detail around edges and seams.

Rubber and Elastomer Finishes: Bloom, Shine, and Age

Rubbers range from matte neoprene to glossy nitrile and silicone. New rubber often carries a uniform satin with rounded highlights; talc or mold release can mute it. Aging introduces “bloom,” a waxy haze as plasticizers migrate to the surface, which desaturates color and raises roughness. Ozone cracking etches fine, parallel cracks that open at bends, especially around gaskets. Vulcanized surfaces buff to higher gloss at contact arcs and hold dust stubbornly, which cuts highlights and shifts hue. Painted markings on rubber smear and fade rapidly, while engraved or molded marks retain legibility through wear.

Clearcoats, Sealers, and Sheen Maps

Many materials accept a protective or aesthetic top layer that decouples color from gloss. Clearcoats on metals and woods add depth and slow oxidation, while sealers on porous materials control stain uptake. In shaders, treat clearcoats as a second specular lobe with its own roughness and IOR so highlights can sit “above” the base. Sheen maps can target fabric fuzz and oiled wood highlights separately from base roughness. In physical builds, choose rattle‑can clears carefully; some warm the tone and all change how dust clings. A thin, uneven clear tells of hurried over‑the‑top protection and creates drip runs and dry‑spray bands that catch light differently.

Wear Logic: How Finishes Fail in Use

Finishes fail at edges, handles, and interfaces. High‑spots polish glossy, matte chalks brighten, and clearcoats thin over corners. Paint chips at impact points and creeps back from rusty edges. Anodize thins without peeling and shows whitened scrubs where abrasion cut into the porous layer. Plating pits and peels from pinholes when corrosion creeps under edges. Oils in wood finishes darken grip zones and leave rag‑wipe arcs near joints. Fabrics grow glossy along stress lines as fibers align, while DWR loses beading in elbow creases first. Rubber brightens to gray at flex creases and attracts micro‑dust in sweat lines. Map these failures to believable hand paths and motion so the surface language explains function.

Readability at Distance and Under Lighting

At cinematic or gameplay distances, finish matters more than micro detail. A high‑gloss clearcoated color field reads like a hard, expensive object; a satin, orange‑peel powder coat reads industrial and robust; a chalked enamel suggests age and neglect. Use value and gloss blocks to stage silhouette and grip points, then reserve small islands of specular pop for hero reads such as a polished knob or a lacquered inlay. Test under multiple HDRIs or on set with practical lights so your finish reads consistently; some sheens invert under cool versus warm key lights and can betray a mismatch between concept and capture.

Communicating Finish Intent in Concept Packages

For each material zone, write a paragraph that states substrate, treatment, gloss target, and age state. A note such as “Aluminum receiver, Type II anodize dyed charcoal, satin clear, light edge rubs to bright; steel fasteners, black oxide with oil—polished on heads; grip, waxed ash with open pores, satin; optic, AR‑coated glass with faint purple hue, smudged wipe arcs” gives production a recipe, not just a look. Include a neutral‑lit swatch sheet with small spheres for each finish, a value map without hue, and close‑up paintovers showing wear at the three touchpoints that matter.

Production Notes: Modeling, Surfacing, and Physical Build

Model subtle bevels to catch clearcoat highlights and avoid razor‑thin edges that make even glossy finishes read dull. In surfacing, layer finish history in order: base substrate response, conversion layers or plating, primer, color, clear, then use‑driven wear and ambient grime. Keep roughness variation doing most of the heavy lifting; specular color should be stable across dielectrics and only change for metals. For physical props, choose finishes that survive handling and match on‑camera intent: powder coat for durable industrials, rattle‑can lacquer for quick gloss, shellac or oil‑wax blends for warm woods, spray‑on DWR for readable fabric beading, and matte acrylic clears to unify mixed donors without killing their story.

Environment and Locale: Finish Dialects

Finish choice signals culture and climate. Coastal factions prefer galvanizing, epoxy paints, and oiled woods to resist salt; deserts chalk everything and justify fabric wraps and waxed finishes for dust shedding; snowbound regions prize satin metals, rubber boots, and heavy clearcoats that resist moisture ingress; industrial enclaves show nickeled hardware, gray powder coats, and serialized stencils. Choose two or three finish constants per faction so their kit shares a surface dialect even as forms vary.

Testing, QA, and Iteration

Before locking a finish, test it under abuse. Smudge screens, scratch lacquer, soak fabrics, and leave metal samples outdoors. In engine or renderers, rotate through HDRIs to ensure the chosen roughness range maintains silhouette reads and material separation. On physical builds, do a quick “shine map” pass by handling the prop for a few minutes; wherever your hands polished or dulled the surface should receive the corresponding shader tweak or weathering paint.

Final Thoughts

Surface language is the handshake between form and light. When you choose coatings and finishes with an understanding of how they are built, how they age, and how they read under production lighting, your props gain price, provenance, and plausibility. Lead with value and gloss, specify the stack, and let wear follow function. The result is not just pretty surfaces, but truthful ones that invite touch and tell time.