Cast Acrylic vs Extruded Acrylic: Which One Fits Your Project

Acrylic sheets are a popular substitute for glass. They are lightweight, resist shattering, and fabricate well. But not all acrylic sheets perform the same.

Two main types exist. Cast acrylic and extruded acrylic look identical at first glance. Their manufacturing processes differ completely. That difference drives performance, price, and where each one belongs.

This article explains how each type is made, what properties matter, and which one suits your project.

What Is Cast Acrylic

Cast acrylic is a premium sheet. It starts as liquid methyl methacrylate monomer poured between two glass plates. Polymerization turns the liquid into a solid. The result is a rigid material with excellent clarity and weather resistance.

How It Is Made

The process runs in batches. Glass plates are assembled with a gasket that sets thickness. Liquid monomer mixed with initiators is poured into the mold. The mold goes into a temperature controlled oven for 8 to 24 hours. After slow cooling, the glass plates come off. Edges are trimmed and polished.

Key Properties

Cast acrylic is well-valued for several reasons. Light transmission reaches 92 percent, rivaling glass at half the weight. Even after laser cutting, clarity remains. Thickness ranges from 1.5 mm to 50 mm or more. Internal stress is very low, making it suitable for CNC work. Regardless of sun exposure, cast acrylic resists yellowing for ten years or more. It handles heat, humidity, and freezing conditions.

Advantages

Low internal stress prevents crazing during cutting. Cast acrylic is ideal for premium displays and museum exhibits. It offers good impact strength, much stronger than glass. Outdoor signage and solar panel covers last for years. Fabrication is precise.

Disadvantages

Cost is higher, typically 20 to 50 percent above extruded. Thick sheets are heavy, adding shipping costs and requiring stronger mounts. For weight sensitive projects like suspended signs, cast acrylic may be too heavy.

What Is Extruded Acrylic

Extruded acrylic focuses on cost efficiency and high volume. It is made by forcing melted PMMA pellets through a shaped die.

How It Is Made

The process is continuous. Pellets are fed into a heated barrel and melted between 180 and 250 degrees Celsius. The molten acrylic is forced through a flat die into sheet form. Calender rollers flatten and cool the sheet. It is then trimmed to standard sizes, typically 4 by 8 feet.

Key Properties

Continuous production gives uniform appearance, though flow lines may show under polarized light. Extruded acrylic works for general signage but not luxury displays. It bends well for curved surfaces. Standard sizing is 4 by 8 feet. Scratch sensitivity is higher due to lower hardness.

Advantages

Cost savings are significant, typically 20 to 30 percent cheaper than cast. Extrusion lines run 24 hours a day. Thickness tolerance is tighter at plus or minus 5 percent. Uniform thickness reduces waste. Extruded sheets are often thinner from 1 to 5 mm, reducing weight. Handling is easier for mobile displays.

Disadvantages

Lower surface hardness means more scratching. Without UV stabilizers, extruded acrylic yellows or becomes brittle within three to five years outdoors. It cracks more easily under stress. Internal stress shows as flow lines. Light transmission is 88 to 90 percent, lower than cast. The finish looks flatter.

Key Differences

Manufacturing. Cast uses liquid monomer in batches. Extruded uses melted pellets continuously.

Clarity. Cast offers 92 percent transmission with minimal distortion. Extruded gives 88 to 90 percent and may show flow lines.

Durability. Cast resists UV and weathering for years. Extruded yellows within three to five years outdoors without stabilizers.

Thickness. Cast goes up to 50 mm or more. Extruded is typically 1 to 10 mm.

Cost. Cast costs 20 to 50 percent more. Extruded is more affordable.

Machining. Cast handles laser cutting and engraving well. Extruded may melt or warp.

Best Uses for Cast Acrylic

Cast acrylic excels where clarity and durability matter. High end retail signage and backlit logos use it. Architectural applications like skylights and facades rely on cast acrylic. The Dubai Mall Aquarium uses cast panels over 30 inches thick. Outdoor signage and solar panel covers benefit from UV stability. Corporate awards and trophies are often made from cast acrylic.

Best Uses for Extruded Acrylic

Extruded acrylic suits indoor, light duty, or budget projects. Retail signage and promotional displays work well. Protective barriers like sneeze guards are commonly made from extruded acrylic. Furniture and DIY projects such as shelves and tabletops are cost effective uses. For short term campaigns, extruded display stands can save up to 40 percent in material costs.

How to Choose

Start with your application. Choose cast for outdoor signage, aquariums, high end displays, and UV exposed environments. Choose extruded for indoor signage, temporary installations, menu boards, and curved setups.

Look at your budget. Cast costs more. Reserve it for long term projects. Extruded offers savings for bulk orders.

Consider fabrication. Cast machines easily. Extruded works for basic cutting but may struggle with laser engraving.

Think about longevity. Cast provides ten plus years of UV stability. Extruded may yellow within three to five years.

Conclusion

Cast and extruded acrylic look the same on a shelf. But once installed outdoors or machined, the differences become clear. Cast sheets deliver exceptional clarity and durability for long term performance. Extruded sheets offer cost savings and flexibility for budget sensitive installations.

Walglas supplies both types. Contact us for technical data and sample sheets.