plexiglas

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

I don't buy much plexi or other other plastics for that matter and could use some help narrowing down what option is best for me. It's a tad daunting to sift through all the different types, materials, finishes, or treatments. I need to get the cheapest option for me without unknowingly paying...