Best reflective surface for a micro grow

ok i am building a very small grow box to grow mothers for the summer and i am new to indoor growing. i currently have two different materials on hand to use for my grow box and i was wondering, which would be most suitable to get maximum potential out on my 3, 30 watt cfl lights i will be using. one of materials i have is good old tinfoil, seems like my best choice but ive heard it can create hot spots even if its put on the non shiny side. The second material i have is a plastic left over from a very large indoor grow (not mine) one side is black and one is white, and obviously the white side was used before.
Please help me with this as i need an experts opinion. but any input is appreciated thanks!

id personally go for the tin foil mate , but not if ur gonna use that previous tent construct something with that

Most people advise to stay away from the foil. It might not create hot spots on the dull side, but it tears easily and if you were thinking of glueing it in place, this will be toxic for your plants grown in a small place. My opinion would be to use the white plastic, or get some mylar from your local hydro store and keep it in place with some non toxic adhesive.

I was considering using foil myself some time back, went a different route but did try something with foil that worked nicely
spray painted the dull side of the foil with flat white spray paint, got a beautiful white surface
i still have that foil(pack rat i guess), and 2 years later the painted surface is just as nice as 2 years ago

You can get a mylar survival blanket for a dollar and it will cover it all. You can't beat the price or reflectability.