Flame Retardant Acrylic Sheets

[OOBTD]

Hello, The designer for project I am working on in a 99 seat house in NYC has just added about 320 sq ft of mirror plexi to the set.
Aside from the additional cost (!) I’m wondering about methods to apply FR treatment without ruining the reflective surface.
Any ideas or experience welcome
Thanks

 

[Malabaristo]

Even if you were not concerned about surface finish, I doubt you'd find an effective treatment. The problem with thermoplastics is that they melt before their ignition temperature, so any surface treatment is likely to be circumvented before it can serve it's purpose. There's also smoke and other harmful fumes produced before it actually burns, so preventing it from igniting doesn't necessarily make it safe anyway.

If you have a working relationship with your local AHJ (fire marshal), it would be good to arrange a conversation on what they would like to see. It may work out that they'll give you a threshold for how much of the material they're okay with you using based on the size of your space and other considerations.

Have you looked into mirror film? Rosco's looks to be discontinued, but Rose Brand sells something similar in pre-assembled (expensive...) panels. Haven't looked any further than that to see if there's somewhere else you could buy it by the roll, but it's worth some research. Depending on what it's made of, it's likely to be much less flammable, and either way there's a lot less material involved.

 

[Van]

As @masaid above, applying a coating is really not a option. Acrylic sheet is tricky. It meets flame spread specs but its smoke output and toxicity renders it unsable as a building material. Now, that is Building Code standards for set/display items can vary widely.