Crazing
Crazing — A cluster of fine internal cracks that appears where stored stress in the sheet meets a chemical attack. It is not a surface stain: the cracks scatter light from inside the wall, so polishing cannot remove it, and once it appears it tends to grow.
Solvent attack
Solvent attack — Glass cleaners and solvent wipes partially dissolve the acrylic surface at a molecular level, leaving haze, dulled gloss or white marks. This is not a quality issue with a particular manufacturer; it is the nature of the material itself.
| Dry dust | blast or brush off first, then dry-wipe with microfibre only |
|---|---|
| Fingerprints | diluted dish soap and water, soft cloth |
| Oil marks | same solution, several passes, no pressure |
| Glass cleaner | never — ammonia triggers stress cracking |
| Paper towels | never — wood fibres leave micro-scratches |
Acrylic is softer than glass — start with the scratches
Acrylic matches glass for clarity and loses badly on surface hardness. The same silica particle in ordinary dust is harmless on glass and is a tiny cutting edge on acrylic, which is why the cleaning order matters: blow or shake the dust off before any cloth touches the panel, and lift soil with soapy water rather than wiping it dry. Dragging a dry cloth across a dusty display presses that dust into the surface as an abrasive slurry. Paper towels fail the same test from the other side — their wood fibres are harder than acrylic, so every wipe scatters fresh micro-scratches that later read as a permanent haze under spotlights. Cotton or microfibre cloths, washed between jobs, are the whole equipment list.
Haze and cracking are different accidents
Solvent attack and crazing get described as one problem, but they are two. Solvent attack is a surface accident: the cleaner dissolves the top layer, leaving dulled gloss, whitening, or in bad cases a groove — and this type is the one polishing can fix. Crazing is different: chemicals released from ammonia glass cleaners, alcohol wipes or aggressive adhesive removers let the stress locked inside the sheet relax by cracking, thousands of micro-cracks that scatter light from within. Because the cause is the stress itself, no polish removes it. The three most-pressed release switches are exactly the products bought for other materials: ammonia window cleaner, alcohol sanitising wipes, and scented solvent cleaners.
Placement decides where the first crack starts
Look at where display cases actually fail and there is a pattern in the stress. First, around screws and fittings: fastening acrylic like plastic hardware stores teach you keeps a permanent bend across the sheet thickness, and spray mist from cleaning drifts into the holes, so weeks later the veining starts there. Second, by windows: sunlight raises temperature and relaxes stored stress faster, showing up as bow before it shows up as cracks. Third, at the base: if the shelf is not flat, every item placed on the tray bends the panel on a local high point. How long an acrylic display lasts is decided less by the grade of the sheet than by these three placement conditions.
When haze appears, can polishing bring it back?
If the haze is only on the surface, an acrylic polishing compound can remove it together with the shallow scratches around it. Crazing cannot be polished out, because the cracks sit inside the sheet. Look at the clouded area under raking light first: scratches that sit on the surface are repairable; a glow that lives inside the wall means you switch to management — keep it away from solvents and heat and stop treating it as a fresh panel.
Why do the first cracks appear near holes and corners?
Because that is where machining leaves the highest concentration of internal stress: around over-tightened screws, along cut edges that were never flame-polished, at the corners of press-fit fittings. When solvent reaches those zones, it does not create the stress, it only shortens the waiting time until the stress finds a crack. The fix is upstream: snug rather than tight fastening, finished edges, and cleaning cloths that never carry solvent near the fittings.