Tempered Glass or Acrylic for Museums
I've been specifying glazing for museum cases since 1996. The acrylic versus glass debate comes up on every project. Twenty years ago I defaulted to glass. Not anymore.
The old acrylic was bad. The Plexiglas from the 80s yellowed within a few years. It scratched constantly. Conservators wouldn't touch it. That reputation stuck around longer than it should have.
The chemistry changed. Acrylite, Optium, Tru Vue products. The Japanese manufacturers got serious about optical grade material. Around 2008 I started switching my recommendations. By 2015 I was specifying acrylic for maybe 70% of my projects.
Weight is the first thing. A quarter-inch acrylic panel weighs roughly half what glass does. For a medium-sized traveling exhibition, you're looking at hundreds of pounds difference across all the cases. Shipping costs drop. Crate sizes shrink. The installer doesn't need as many people on site.
Safety changed my mind more than anything else. I was consulting on a natural history project in 2011 when a maintenance worker knocked a glass panel off a case. Tempered glass. It shattered the way it's supposed to, small pieces everywhere. Took them four hours to clean up. The specimen behind it was fine but nobody wanted to think about what could have happened.
Acrylic doesn't shatter. It cracks. It stays in one piece. For seismic zones this matters even more. I've done two projects in California where the building code basically pushed us toward acrylic anyway.
The scratch issue is real but overstated. Yes acrylic is softer than glass. Yes you need to be more careful cleaning it. The newer coatings help. I have cases from 2012 that still look good. The trick is training your staff. Microfiber cloths only. No paper towels. No spray bottles near the surface.
Static buildup attracts dust. I won't pretend otherwise. You clean acrylic cases more often than glass. Maybe twice as often in dry climates. For most institutions that's not a dealbreaker. It's a staffing consideration.
UV blocking is basically equal now. The museum-grade acrylics filter 98 or 99 percent of ultraviolet. Glass with coatings does the same. I don't factor UV into material decisions anymore.
Cost is where people get confused. Glass costs more per square foot. Acrylic replacement happens sooner. If you run the numbers over 25 years the gap closes. But most museum budgets don't work on 25-year cycles. They work on this fiscal year. Acrylic wins on upfront cost almost every time.
I still specify glass occasionally. Very high-end permanent installations where the client wants maximum optical clarity and has budget for anti-reflective coated glass. That's maybe 15% of my work now.
The industry moved toward acrylic for good reasons. Some of my older colleagues still resist it. They remember the yellowing problems from decades ago. That's not the product we're working with anymore.
