mylar question

i making a cfl box that has a frame made out of wood and im covering it with mylar but a lot of light seems to juss go thru tha mylar. is this bad or does it make a difference?

The light should not be able to penetrate the mylar. The only leaks should be in the seam joints and can be easily covered with aluminum duct tape. If light is shining through the mylar you could use a layer of black plastic sheeting before installing the mylar.

thin mylar lets some light in but for the most part if you have a backing to the mylar, cardboard or plywood it works just fine, I have never used it just by itself, it was always attached to something.