Short answer
For furniture that must look like a clear slab, carry a concentrated load, or be edge-polished and solvent-bonded, specify solid acrylic sheet. For a light cover, a non-structural screen, or a large area where weight matters more than optical depth, a hollow or multiwall acrylic panel can be the better fit. They are different constructions, not two grades of the same board.
Solid acrylic is a continuous polymethyl methacrylate (PMMA) sheet, usually cell-cast or extruded. A hollow acrylic panel has internal ribs, cells, or an open core. That internal geometry changes weight, stiffness in one direction, light scatter, edge appearance, and how the part can be cut and joined. A thick-looking tabletop made by boxing thinner solid sheet is a third case: it can look solid from the face, but it is a fabricated assembly, not a solid panel.
What each panel is
Solid acrylic sheet
Solid acrylic is PMMA through the full thickness. ASTM D4802 is the common U.S. specification for PMMA acrylic plastic sheet and separates sheet by manufacturing category, including cell-cast, continuous-cast, and extruded types. Cell-cast sheet is often chosen when optical quality, chemical resistance, and thicker sections matter. Extruded sheet usually has tighter thickness control and is easier to thermoform, but it is generally less suitable for aggressive solvent cementing.
In furniture, common specified thicknesses run from about 5 mm for small shelves and liners to 20 mm or more for legs, beams, and unsupported tops. Thicker solid stock exists, especially in cast sheet, but price, weight, and polishing time rise quickly. Those ranges are purchasing practice, not a strength rating.
Hollow acrylic panels
Hollow acrylic usually means a structured sheet: twin-wall, multiwall, or a ribbed extrusion with air channels. Some sign and partition panels use this form because it is lighter than a solid sheet of the same outside thickness. Face skins can be clear, but the ribs break the view and scatter light. Cut edges show the cell pattern unless they are capped.
Do not treat “hollow” as a material grade. Ask for the wall thickness, cell direction, overall thickness, and whether the panel is acrylic or another plastic. Polycarbonate multiwall sheet is sometimes sold in the same conversations and does not machine or bond like PMMA.
Side-by-side comparison
| Point | Solid acrylic sheet | Hollow acrylic panel |
|---|---|---|
| Structure | Continuous PMMA through the thickness | Skins plus ribs or cells, with air inside |
| Typical furniture use | Tops, legs, shelves, boxes, bonded frames | Light covers, screens, non-load panels |
| Optics | Clear faces and polished edges can read as glass | Ribs are visible; light scatters at the cells |
| Weight | Higher for the same outside thickness | Lower for the same outside thickness |
| Edge | Can be cut, routed, and diamond-polished | Open cells need a cap or will stay visible |
| Joining | Solvent bonds and mechanical fixings are both used; method depends on cast or extruded grade | Bond area is mostly the skin; cell walls crush if over-clamped |
| Point loads | Better when thickness and span are specified together | Skin can dent or crack over a small contact area |
| Span direction | Similar in both directions if the sheet is uniform | Stiffer along the ribs than across them |
| Heat forming | Extruded sheet forms more readily than many cast sheets | Cells can collapse or distort when heated |
Published optical and mechanical figures for PMMA vary by grade, thickness, and test method. A supplier data sheet with the test standard is more useful than a single “acrylic strength” number.
Parameters to specify
A useful panel callout names the construction, not only the word “acrylic.”
- Construction: solid sheet, hollow multiwall, or a fabricated hollow box made from solid sheet.
- Polymer and grade: PMMA, and cast or extruded if it is solid sheet. ASTM D4802 category is a useful reference when the buyer needs a defined sheet class.
- Overall thickness and, for hollow sheet, wall thickness. Nominal thickness is not the same as minimum thickness. Cast sheet often has a wider thickness tolerance than extruded sheet.
- Color and finish: clear, tint, frosted, matte, or polished. Frosted faces hide scratches better and reduce see-through.
- Span, support spacing, and the heaviest expected load. A 10 mm solid shelf that is fine at 400 mm may not be fine at 900 mm.
- Edge treatment: sawn, routed, flame-polished, or diamond-polished. Hollow edges usually need an inserted or bonded cap.
- Joint method: solvent cement, structural adhesive, screws into a boss, or a mechanical frame. Do not assume every acrylic bond is invisible.
Specific gravity of ordinary cast PMMA sheet is often listed around 1.19 in supplier tables, so a solid panel is close to the weight of a same-size glass pane and much heavier than a multiwall panel of the same outside size. Use the sheet supplier’s figure for the grade you buy; impact-modified acrylic can differ.
Where each type fits
Choose solid sheet
- Coffee tables, side tables, shelves, and legs where the edge is part of the look.
- Display cubes and podiums that are solvent-bonded and then polished.
- Parts that must be CNC-routed, drilled, or engraved through the thickness.
- Surfaces that take a vase, laptop, or leaning person, once thickness and supports are sized for that load.
Choose hollow panel
- Large lightweight covers, illuminated faces, and privacy screens where ribs are acceptable.
- Temporary partitions and sign bodies where freight weight matters.
- Panels that sit in a frame, so the open edge is hidden.
Choose a fabricated box instead of either raw panel
A side table or plinth can be built from thinner solid sheet as a closed box. It uses less material than a thick slab and can still have polished outer edges. The tradeoff is more joints, a visible bond line if the polish is not controlled, and less resistance to a sharp point load on a thin top skin. This is a design choice, not a cheaper version of thick cast sheet.
Fabrication limits
Acrylic is notch-sensitive. A square inside corner or an unchamfered drilled hole is a common crack start, in solid sheet and in hollow skins. Leave a radius at inside corners and avoid forcing screws through an unsupported cell wall.
Solvent cement works on compatible PMMA surfaces when the joint is clean and clamped without starvation or flooding. Extruded sheet is more prone to crazing from some solvents than cell-cast sheet, so the cement system should match the grade. Hollow panels give the cement very little contact area.
Heat is another limit. PMMA softens well below the temperatures used for many other plastics. A panel behind glass in full sun, or next to a lamp, can bow even when the room feels moderate. Hollow cells can also trap heat. If the location is hot, ask for a sample in that orientation before approving a long span.
Outdoor use needs a UV-tolerant grade if yellowing matters. Standard indoor sheet and an exterior sheet are not always the same product.
Buying checklist
- State solid, hollow, or fabricated box in the drawing title.
- Give outside size, thickness, tolerance, color, and surface finish.
- Mark load direction and rib direction if the panel is hollow.
- Show supports. Do not leave span to the factory’s guess.
- Specify edge polish and whether joints may show a bond line.
- Ask which sheet category will be used, and for a sample corner before a production run.
- Confirm packaging. Polished faces mark easily in transit.
FAQ
Is hollow acrylic as strong as solid acrylic of the same thickness?
Not in general. The same outside thickness does not mean the same amount of material or the same behavior under a point load. A hollow panel can be stiff along its ribs and still dent between them. Compare section, span, and load, not the nominal thickness alone.
Is Plexiglass the same as solid acrylic?
Plexiglass, Perspex, and Lucite are trade names often used for PMMA sheet. The name alone does not tell you whether the sheet is cast, extruded, solid, or structured. Ask for the product grade.
Can hollow acrylic be polished like a furniture edge?
The face can be cleaned and lightly finished. A cut edge exposes cells, so it will not polish into a clear solid edge. Cover that edge with a cap or place it inside a frame.
Why do two “10 mm” sheets weigh differently?
One may be solid and the other multiwall. Cast and extruded solid sheets can also differ slightly in actual thickness because their tolerances differ. Weigh a sample or calculate from the supplier’s density and measured thickness.
Which should a buyer use for a clear side table?
Solid sheet, or a box fabricated from solid sheet. A hollow panel will show ribs and is a poor match for a polished furniture edge. Thickness still has to match the top span and the load.
About the manufacturer
The comparison above is general acrylic fabrication guidance. It is separate from any one factory’s catalog.
Sunday Knight Acrylic Furniture is a custom acrylic furniture manufacturer in Dongguan, Guangdong, China. The factory makes made-to-order acrylic tables, chairs, podiums, display pieces, and related furnishings for residential, retail, hospitality, and exhibition projects, with OEM and ODM work based on drawings or samples. Public company pages describe in-house cutting, CNC machining, bending, bonding, polishing, and assembly. Product examples are listed under products and acrylic tables. Project inquiries go through contact.
Panel choice for those pieces is still a specification decision: solid sheet for polished structural parts, a fabricated box when a thick appearance is wanted without a solid slab, and hollow panel only when ribs and open edges are acceptable.
Sources
- ASTM D4802-16(2024), Standard Specification for Poly(Methyl Methacrylate) Acrylic Plastic Sheet. Defines PMMA acrylic sheet and manufacturing categories such as cell-cast and extruded sheet. It is a specification, not a furniture load rating.
- ASTM D792, Standard Test Methods for Density and Specific Gravity (Relative Density) of Plastics by Displacement. Density should be read from the grade’s own test report.
- ASTM D1003, Standard Test Method for Haze and Luminous Transmittance of Transparent Plastics. Optical claims need the test method and sample thickness.
