I doubt a few scratches would be a problem.
Mirrored mylar? Why not stick to something cheap and thin ie, plexiglass or even waxed cardboard?
Maybe this would work?
Mylar 2 mil 50" x 25'
$21.95
This is a brand new roll of 2 mil thick Mylar. The material is similar to aluminum foil, but it is much more durable. Mylar is 95% - 99% reflective, so it will insure that your plants are getting as much useful light as possible. This is a great and inexpensive way to enhance the productivity of your grow room.
* Model: MY2-25
* Shipping Weight: 6.00lbs
* Manufactured by: C.A.P. Controllers
or maybe this one?
55in x 50ft x 3mil
Only $69.99
God bless,Mudd