Acrylic Plastic FAQ — Drilling, Cleaning, Scratches, UV & More

Common questions from engineers, fabricators, and buyers about acrylic — answered directly with specific parameters, not generalities. If your question isn't here, it is likely covered in the linked spoke pages.

At a glance:

• Acrylic cracks at drill breakthrough without the correct bit geometry — 60° angle drill or brad-point
• Cast vs. extruded decision hinges on whether you're laser cutting or thermoforming
• Clean acrylic with mild soap and water or plastic-safe cleaner only — never Windex or acetone
• Surface scratches can be polished out; deep scratches require wet sanding
• Standard acrylic holds clarity outdoors for 10+ years; polycarbonate yellows in 3–5 without coating
• Solvent bonding (Weld-On 4) works only on acrylic, not on mixed-material assemblies

Q1: Does acrylic crack when drilling? How do I prevent it?

Yes — if you use the wrong drill bit or technique. The issue is bit geometry. A standard twist drill (118° or 135° included angle) applies a wedging force at breakthrough that stress-cracks acrylic, especially thin sheet.

How to prevent cracking:

1. Use a 60° included-angle drill bit (modified for plastics) or a brad-point bit. These geometries shear the material rather than wedge it.
2. Place a sacrificial backer (scrap wood or acrylic) under the workpiece at the drill point. This supports the material at breakthrough and eliminates the unsupported breakout zone.
3. Ease off feed pressure as the drill nears the far face. High pressure at breakthrough is the most common cause of cracks.
4. Drill speed: 500–1,500 RPM for most bit sizes. Slower for large diameters. High speed generates heat that melts rather than cuts.
5. For holes near edges, keep the hole center at least 1.5× the hole diameter from the sheet edge to avoid edge splitting.

Plastic-specific drill bits are inexpensive and eliminate the geometry variable. For full drilling parameters, see the acrylic machining guide.

Q2: How do I choose between cast and extruded acrylic?

The fabrication method drives this decision in most cases:

In short: cast for optical/laser/bonding work; extruded for forming and cost-sensitive applications.

If you're uncertain, review the grades page for a full side-by-side property comparison.

Q3: What is the correct way to clean acrylic?

Use mild dish soap and warm water with a soft, clean microfiber cloth. This is the safest method for all acrylic grades.

Products to avoid:

• Windex and ammonia-based cleaners — craze acrylic; the resulting fine cracks cannot be repaired
• Acetone, MEK, or solvent-based cleaners — dissolve the surface
• Isopropyl alcohol above ~30% — can craze some grades under stress
• Paper towels — wood fibers scratch acrylic; use microfiber only
• Dry wiping — always dampen the cloth first to lift grit rather than drag it

Approved cleaning options:

• Mild soap and water
• Novus Plastic Polish #1 (cleaner and light polish)
• Brillianize antistatic plastic cleaner
• Acrylic-specific sprays from display suppliers

For food-service OP-3 acrylic, use food-safe cleaners. Quat sanitizers at food-safe dilutions are generally acceptable — verify with your cleaner supplier.

Q4: Can scratches on acrylic be repaired?

Yes — for most scratches. The approach depends on scratch depth:

Fine surface scratches: Apply Novus Plastic Polish #2 with a clean microfiber cloth in a circular motion, followed by Novus #1. This removes swirl marks and fine scratches in one or two applications.

Moderate scratches (not deep enough to snag a fingernail): Wet sand with 800-grit paper, then 1500-grit, then polish with Novus #2 and #1.

Deep scratches (snag a fingernail): Wet sand progressively: 400 → 600 → 800 → 1500 grit, then buff with plastic polishing compound on a muslin wheel.

What you cannot repair: Crazing (fine network cracks from solvent or ammonia exposure) is subsurface — it cannot be polished out. Crazed acrylic must be replaced.

Q5: How does acrylic perform outdoors? Will it yellow?

Standard cast acrylic does not yellow in outdoor UV exposure. This is one of its primary advantages over polycarbonate. Clear cast acrylic retains its optical clarity and surface finish after 10+ years of outdoor exposure in temperate to tropical climates — without a UV-protective coating.

Polycarbonate, by contrast, yellows and hazes in 3–5 years of uncoated outdoor use. Coated polycarbonate (UV cap layer) extends outdoor life, but the coating itself can fail (craze, peel) over time.

Caveats for outdoor acrylic:

• Colored interior-grade acrylic may fade. Specify weather-grade colors for outdoor use.
• Acrylic expands at 3.8 × 10⁻⁵ in/in/°F — provide clearance gaps in frames and oversized fastener holes.
• UV-filtering grades (Acrylite OP-2, Plexiglas UF-3) protect UV-sensitive contents. Standard clear acrylic transmits some UV energy.

See the acrylic properties page for full weatherability data.

Q6: Can I glue acrylic to itself? What about to other materials?

Acrylic to acrylic: Solvent bonding with Weld-On 3 or Weld-On 4 (IPS Weld-On) is the standard method. The solvent (methylene chloride-based) dissolves the surfaces and creates a molecular weld. On cast acrylic, joint strength approaches the tensile strength of the base material (~10,000 psi). On extruded acrylic, the joint is somewhat weaker but adequate for most applications.

Acrylic to other plastics (PC, PETG, ABS): Weld-On 4 does not work on these materials. Use cyanoacrylate (CA) for small joints, acrylic-compatible structural adhesive (Loctite 4308, Weld-On 55) for load-bearing joints, or UV-cure adhesive for transparent mixed-material assemblies.

Acrylic to metal: Use an acrylic-compatible structural adhesive or VHB tape. Solvent cements do not bond metal.

Q7: What is the maximum temperature for acrylic?

Continuous service temperature: 200°F (93°C) for cast acrylic, 180°F (82°C) for extruded acrylic. These represent the maximum temperature for sustained, loaded service — not brief fabrication excursions. Acrylic begins to soften above its heat deflection temperature (185–210°F under load).

Avoid: oven proximity, steam environments, or enclosures where surface temperature exceeds 180°F.

If your application requires a transparent material rated above 200°F, polycarbonate (240°F continuous) is the common alternative, though it does not match acrylic's optical clarity.

Q8: Is acrylic safe for food contact?

Standard acrylic (Acrylite GP, Plexiglas G, generic extruded) is not certified for food contact. OP-3 grade acrylic (Acrylite OP-3) is formulated to meet FDA 21 CFR 177.1010 for use in food-contact articles.

The grade difference matters: OP-3 uses only FDA-permitted monomers and adjuvants at controlled concentrations. It is available with a Certificate of Compliance (CoC) for regulatory documentation.

OP-3 is the correct specification for:

• Bakery display cases, deli shields, salad bar rails
• Produce bins and bulk food displays
• Any fixture where the acrylic surface contacts food or beverage directly

See the FDA and food-grade acrylic guide for the full regulatory discussion.

Q9: How is acrylic different from polycarbonate? Which should I buy?

Both are clear, rigid thermoplastics used in glazing and display. The choice comes down to your priorities:

Buy acrylic when: optical clarity is the priority (92% vs. 88%), the application is outdoors, you are laser cutting, or you need solvent-bonded joints. Acrylic also costs less than polycarbonate.

Buy polycarbonate when: impact resistance is required (30× higher), machine guards or safety glazing, temperature above 200°F, or UL 94 V-2 rating is needed.

See the acrylic vs. polycarbonate comparison for the full property table.

Q10: What sizes does acrylic sheet come in?

Stock sizes: 4′×8′ (universal), 4′×10′, 5′×8′, 5′×10′, and up to 8′×10′ in cast grades (may require indent order). Common thicknesses: 0.093″, 0.118″, 0.177″, 0.220″, 0.250″, 0.375″, 0.500″, 0.750″, 1.000″, and up to 4.000″. Cut-to-size is available for most thicknesses.

For the complete dimensional reference, see the acrylic specifications page.

Still have questions? The full acrylic buyer's guide covers grades, applications, specifications, and machining in one place.

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Frequently asked questions — Acrylic FAQ