Cluster 2 · How to Choose Guide · Specification
Choosing acrylic is a specification problem, not a catalog problem. The useful question is not “which acrylic is best?” It is: what load, span, climate, chemistry, contact type, and finish does the part have to survive? This guide gives decision rules for thickness, outdoor use, retail displays, cosmetics fixtures, and food display — and states where a general rule stops being safe to quote.
How to choose acrylic
Working rule. Choose acrylic when the part needs glass-like clarity, lower mass than glass, and fabrication (cutting, forming, solvent bonding, polishing). Then choose a grade and thickness for the environment. Do not choose acrylic as a default transparent plastic when impact energy, continuous heat, or aggressive solvents dominate.
Acrylic in this guide means PMMA sheet used for fabricated parts. Trade names (Plexiglas, Perspex, Lucite, and others) are brands of that polymer family. A purchase order that only says “clear acrylic” leaves the factory free to pick extruded seconds. That is how two visually similar quotes produce different cracks six months later.
The material primer — chemistry, cast versus extruded, and comparisons with glass and polycarbonate — is in What is acrylic? This article assumes that background and focuses on selection.
A working decision order
Use this sequence. Skipping steps is how indoor extruded sheet ends up on a sun-facing canopy.
- Name the job. Cover, riser, box, outdoor panel, wet-area tray, or food-contact surface. One part can have more than one job.
- Name the environment. Indoor climate-controlled, outdoor UV and weather, hot lighting, cold storage, or splash from cleaners and product.
- Name contact chemistry. Dry goods, water, alcohol, fragrance, oil, acid food, or unknown retail cleaners.
- Choose process route. Cast for machining, bonding, thick plate, and polished edges. Extruded for thin, cost-sensitive, dimensionally even panels and simple heat bends.
- Choose thickness from span and handling, then check heat and fastening.
- Choose color and surface. Colorless, tint, frost, opaque, mirror. Hard-coat only if abrasion is real and the coat is specified.
- Choose compliance documents if the destination market requires them (food contact, toy-adjacent parts, flame rating, RoHS/REACH for the finished article).
What thickness do I need?
There is no universal acrylic thickness. Thickness is a function of unsupported span, point load, how often the part is handled, edge finish, and whether the panel is framed. The bands below are patterns from fabricated retail and hospitality parts. Treat them as starting points for a sample, not as allowable stresses.
| Typical part | Common starting band | Why it moves up | Why it can stay thinner |
|---|---|---|---|
| Price talker, small tag, thin dust cover | About 2–3 mm | Frequent handling, wide unframed face | Fully supported, short span, low touch |
| Counter riser, brochure pocket, small five-sided box | About 3–5 mm | Heavy product, magnet lid, stacked boxes | Small footprint, product sits on a base rather than on the lid |
| Jewelry / perfume stand, makeup organizer, serving tray | About 4–8 mm | Point loads, wet service, visible polished edges | Short shelves with vertical ribs |
| Large display case, pedestal, long shelf | About 5–10 mm, or a ribbed build-up | Long span, public handling, glass-like stiffness | Hidden metal or wood structure carrying the load |
| Outdoor panel or canopy face | Often 5 mm and up; confirm with the glazing method | Wind, thermal movement, fastener distance | Small framed sign insert with close supports |
How to think about span instead of millimeters
A 3 mm panel that is 120 mm wide and fully supported on two long edges can look rigid. The same 3 mm panel as a 400 mm unframed lid will oil-can. If the part flexes in your hands before it is loaded, it will creep or look cheap in service. Add thickness, add a fold or rib, or add a frame. Do not solve a span problem with a harder polish.
Other thickness rules that actually show up on the bench
- Magnet lids and hardware. Inserts and magnets want local thickness. A 3 mm lid with a large magnet can dish.
- Solvent joints. Very thin sheet is harder to cement without squeeze-out or a starved joint.
- Heat. A thin dark panel in sun or over a lamp reaches a higher temperature faster than a thick one.
- Cast tolerance. Cast sheet thickness varies more than extruded. A “5 mm” cast lid may not match a “5 mm” extruded base. Measure, or spec one route for mating parts.
What acrylic is best for outdoor use?
Short answer. For outdoor clarity over time, specify a UV-stable PMMA sheet grade intended for exterior use — often cast for thicker sign and canopy work — and design the part for thermal expansion, water, and fastening. Indoor extruded offcuts are the usual reason an “outdoor acrylic” job yellows, warps, or cracks at the holes.
Unmodified PMMA as a polymer class weathers better than many other clear plastics. That sentence is about the polymer family, not about every sheet in a warehouse. Recycled mix, missing UV stabilization, and printed films change the result. Ask for the mill’s outdoor or accelerated-weathering statement (methods in the xenon or fluorescent families such as ISO 4892) for the exact grade.
Specify this for outdoor parts
- UV-stable, virgin PMMA; prefer cast when the part is thick, machined, or edge-polished.
- Colorless or through-tinted sheet rather than a thin surface paint if the face will be seen from both sides.
- Oversized or slotted holes, or framed edges, so the sheet can move. PMMA expands more than glass and more than many metals.
- Washers or grommets at fasteners. Tight screws in hot sun are a classic crack starter.
- Drainage and a back gap on signs so heat and condensate do not sit against the sheet.
Outdoor jobs where acrylic is usually the wrong default
- Impact-prone barriers and machine-adjacent screens — look at tested safety glazing, often polycarbonate or laminated glass.
- Surfaces that will be walked on or scraped by sand.
- Dark enclosed boxes over hot lamps with no ventilation.
- Any claim of “flameproof outdoor cladding” without a named fire test on the finished system.
What acrylic is best for displays?
Short answer. For most retail and exhibition fixtures, cell-cast colorless PMMA in the 3–8 mm band, with polished edges and solvent-bonded joints, is the usual specification. Extruded sheet is reasonable for simple flat panels, high-volume heat-bent pockets, and hidden parts.
Displays fail in public on edges and joints, not on tensile-strength tables. Cast sheet generally chips more cleanly, takes a clearer polished edge, and is more tolerant of common acrylic cements. That is why a cheaper extruded quote can cost more after edge work and breakage.
Prefer cast when
- Edges are visible and will be flame- or diamond-polished.
- The part is CNC-routed or drilled.
- Joints are solvent-cemented boxes or multi-tier stands.
- Optics cannot show flow lines (museum case, perfume vitrine).
Extruded is enough when
- The part is a thin, even panel or a simple bend.
- Thickness match across a large face matters more than edge jewelry.
- The run is cost-sensitive and the geometry is forgiving.
- The sheet will be framed or laminated to another structure.
Colorless sheet remains the default because it does not compete with the product. Frost and tint help when you need to hide fittings or match a brand color. Mirror acrylic is a different stack (usually a coated sheet) and scratches like a coating, not like solid PMMA.
Sanait’s fabricated examples live under custom display stands and custom acrylic boxes. Use those pages for product form. Use this page for the material call.
What acrylic is best for cosmetics?
Short answer. Specify cast, virgin, colorless or brand-matched PMMA with polished edges. Then treat fragrance, ethanol, isopropyl alcohol, essential oils, and many makeup removers as chemical risks. Acrylic is common in beauty fixtures because it looks clean. It is not chemically indifferent to the products it holds.
Beauty counters combine three stresses: constant handling, alcohol-based formulas, and photography that shows every joint. Cast sheet and diamond-polished edges address the visual side. They do not make PMMA solvent-proof.
Cosmetic-specific choices
- Sheet: Cast, virgin, optical-quality colorless unless the brand requires a tint.
- Thickness: Organizers and testers often start around 4–8 mm so shelves do not sag under glass bottles.
- Finish: Polished edges; avoid rough-sawn faces that hold foundation residue.
- Print: UV print and engraving are common. Confirm that inks and adhesives are compatible with alcohol wipe-down.
- Geometry: Removable trays beat sealed wells. Spilled toner in a closed joint is hard to clean and easy to craze.
What to keep off the acrylic face
Glass cleaner with ammonia, neat alcohol on a dry cloth used as a daily wipe, acetone, and many “disinfecting” sprays are frequent causes of haze and fine cracking. A mild soap and water protocol belongs in the store manual. See also the acrylic maintenance guide.
If the fixture must sit in a wet spa room or hold open jars of oil, build a sample and leave the actual product on the sheet for a timed contact test before the production run. A data sheet will not tell you what a specific fragrance oil does at a polished joint.
What acrylic is best for food display?
Short answer. Separate two jobs. If the sheet only presents packaged food and never touches the edible part, general display-grade PMMA can be specified like any other indoor fixture. If the plastic will touch unpackaged food — bakery domes, buffet shields that are wiped onto the food side, tasting trays, scoop bins — specify a food-contact grade and keep documents for the destination market.
“Food safe acrylic” is not a material property you can assume from clarity. In the United States, rigid acrylic plastics intended for food contact are addressed under 21 CFR 177.1010, which sets identity and extractives conditions for listed compositions. In the European Union, plastic articles intended to contact food fall under Regulation (EU) No 10/2011 (and the framework rules in Regulation (EC) No 1935/2004). Other markets have their own lists. Compliance is for a named composition and a finished article, tested with the right food simulants and time/temperature conditions — not for “acrylic” as a word.
A practical split for buyers
| Packaged / visual display | Direct or reasonably expected food contact | |
|---|---|---|
| Examples | Boxed chocolate in a vitrine; bottled sauce on a riser | Unwrapped pastry under a dome; buffet sneeze guard; tasting spoon rest |
| Usual sheet call | Display-grade cast or extruded PMMA, chosen for optics and span | Producer-documented food-contact PMMA plus compliant adhesives, inks, and magnets |
| Documents to request | Grade name, thickness, RoHS/REACH if the program needs them | Declaration of compliance, grade CAS/trade name, intended food types and temperatures |
| Heat | Ambient retail | Do not assume PMMA for hot-hold surfaces; check service temperature against the grade |
| Cleaning | Dust and mild soap | A written protocol that avoids crazing solvents still used in many kitchens |
Printed logos, recycled content, and some coatings can take an otherwise eligible sheet out of a food-contact claim. If the program ships to both the US and the EU, say so on the RFQ; the paperwork is not identical.
Selection matrix
| Use case | Process route | Starting thickness band | Watch-outs |
|---|---|---|---|
| Indoor retail display | Cast for visible edges; extruded for simple panels | 3–8 mm for most fixtures | Span, public handling, cheap extruded on polished edges |
| Outdoor sign / canopy face | UV-stable PMMA, often cast when thick | Often 5 mm+; confirm support spacing | Expansion, dark colors, tight fasteners, indoor grades |
| Cosmetics organizer / tester | Cast, virgin, polished | 4–8 mm common | Alcohol and fragrance crazing; dirty joints |
| Food, packaged only | Display-grade PMMA | Follow span rules | Do not call it food-contact on the drawing |
| Food, direct contact | Documented food-contact grade | Follow span plus hygiene design | Inks, adhesives, magnets, heat, kitchen cleaners |
| Impact shield / machine guard | Usually not general PMMA | — | Use a tested safety material instead |
What to put on a request for quote
- Process route: cast or extruded (or “factory to recommend, state which”).
- Thickness and whether mating parts must match within a stated tolerance.
- Color, opacity, and whether the face is seen from one side or two.
- Environment: indoor, outdoor, wet, hot lighting.
- Contact: packaged goods only, cosmetic formula splash, or food contact (market named).
- Finish: sawn, flame polish, diamond polish, frost, print, engraving.
- Hardware: magnets, hinges, locks — and whether they sit on the food or cosmetic side.
- Destination country and any required declarations.
Factory sampling, MOQ, and shipping terms for Sanait jobs are on the custom acrylic FAQ. They are commercial terms, not material properties.
FAQ
Is thicker acrylic always better?
No. Extra thickness adds stiffness and mass, and it can improve a polished edge. It does not fix a bad fastener, a solvent attack, or a heat source. On small parts, extra thickness only adds cost and weight.
Can I use the same sheet for indoor displays and outdoor signs?
Only if the grade is specified for outdoor UV stability and the design allows expansion. An indoor extruded leftover is not an outdoor sheet.
Is extruded acrylic bad for displays?
No. It is a poor default for visible polished boxes and heavily machined stands. It is a reasonable default for thin even panels and simple bends.
Will cosmetic alcohol destroy acrylic?
Short, occasional contact often leaves no mark. Repeated wet contact, especially at stressed edges and solvent joints, can haze or craze PMMA. Test the actual formula on a sample coupon from the production sheet.
Is clear acrylic automatically food safe?
No. Food-contact use depends on the composition, the finished article, the food type, the temperature, and the market’s rules. Clarity is not a compliance test.
Should I specify a trade name or “PMMA cast sheet”?
Specify the polymer, the process route, thickness, color, and documents. A trade name can be added if a program is locked to one mill. A trade name alone is not a complete spec.
When should I choose polycarbonate instead?
When the part must absorb impact energy or sit at a higher service temperature than general-purpose PMMA allows. Expect lower scratch resistance and different bonding methods.
Sources
Standards and regulations below define test methods or legal conditions. They do not pick a thickness for a brochure holder. Producer data sheets still govern a named grade.
- ISO 7823-1:2003, Plastics — Poly(methyl methacrylate) sheets — Part 1: Cast sheets. iso.org
- ISO 7823-2:2003, Plastics — Poly(methyl methacrylate) sheets — Part 2: Extruded sheets. iso.org
- ISO 4892 series, Plastics — Methods of exposure to laboratory light sources. iso.org
- 21 CFR 177.1010, Acrylic and modified acrylic plastics, semirigid and rigid. U.S. Food and Drug Administration. ecfr.gov
- Commission Regulation (EU) No 10/2011 on plastic materials and articles intended to come into contact with food. eur-lex.europa.eu
- Regulation (EC) No 1935/2004 on materials and articles intended to come into contact with food. eur-lex.europa.eu
- “Poly(methyl methacrylate).” Wikipedia. en.wikipedia.org
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