A jeweller asked for “bulletproof glass” after a window was smashed with a hammer. The threat was not a bullet. It was a 2 kg hammer swung six times in ninety seconds, and the right product for that is a different sheet.
Two threats, two specifications
Forced entry is measured by how long a panel resists impact from a tool — typically rated in minutes under ASTM F1233 or a manufacturer’s own test. Ballistic resistance is measured by UL 752 against a specific round. A storefront in a mall with a history of smash attacks needs forced-entry performance first; a high-end boutique in a district with armed robbery history needs ballistic rating on top.
A mall storefront, resolved
The window was 1,800 mm × 2,400 mm. The chosen build was a laminated polycarbonate: 8 mm PC + 1.5 mm PVB + 8 mm PC, giving a total of about 17.5 mm and a forced-entry resistance of several minutes against hammer and crowbar attack, at roughly half the weight of a ballistic monolithic sheet of similar protection.
Where the same client wanted display cases protected, the answer was simpler: 8 mm laminated PC glazing on the case fronts, with a lockable hinge rather than a stronger sheet. Case theft usually defeats the latch, not the panel.
The details that decide the outcome
- Frame strength: a rated panel in a light aluminium frame fails at the frame, not the sheet.
- Edge engagement: at least 15 mm of the panel must sit inside the rebate.
- Anchoring: bolts into the wall, not into the shop-fit studwork.
- Sacrificial film: a peelable anti-scratch film saves the panel during fit-out.
Forced-entry selection is covered in forced entry resistant glazing, and the laminated build spec in laminated polycarbonate glazing.
Frequently Asked Questions
Q: Is bullet resistant glazing the right choice for a jewelry store window?
A:Only if a ballistic threat is in the risk assessment. Most smash-and-grab incidents are a forced-entry problem, solved by laminated polycarbonate with rated impact resistance and a strong frame, at lower cost and weight.
Q: What build resists a hammer attack on a storefront?
A:A laminated polycarbonate, for example 8 mm PC plus 1.5 mm PVB plus 8 mm PC at about 17.5 mm, rated for several minutes of forced entry, set at least 15 mm into a frame anchored to the structure.
Send the threat level, opening size and fixing condition to oversales@rpplexiglass.com for a rated polycarbonate panel quotation with UL 752 test backing.