Hey guys, Im wondering if a safety fire blanket could be used as mylar sheeting inside a growroom/tent. One like this.. 2 X FOIL SPACE BLANKET EMERGENCY SURVIVAL BLANKET - 1.6 X 2.1 METRES | eBay
Those will work. Or you could just use flat white paint (cheap, quick, easy, and almost exactly the same reflectivity as mylar without the potential for hot spots). Panda poly film is another option. It's heavy plastic type stuff that's black on one side, white on the other. I like it because it's water proof, so I don't have to worry if I want to spray something inside my closet, and to clean it I just have to wipe it down, plus no damp walls potentially growing mold.
It's fine for a cfl grow in a cardboard box, no need to go overboard with special lining there. If you were using HID you'd want something with a higher reflectivity, CFL doesn't penetrate very far so whatever you use will be mostly aesthetic. Printer paper is another option for you.
If that's the case then flat white paint is your best bet. Plus it's so much easier to work with than mylar or space blankets, which can create hot spots. You can probably ask some friends/neighbors or a thrift store and get an old can of flat white paint for free.