Light reflection

Does reflective insulation work as a mylar substitute? I seen a pic of a grow that looked like its what they used but wasn't sure. My room has presswood so it's rough and it paints like shit. Not sure how much that effects the reflection not being a smooth surface.

Panda film

It's aluminum foil glued to foam. No.

If you can't get your hands on horticulture grade Mylar. Locate the Mylar car windshield sun things. Staple them to the walls. Don't over do the staples so they can be easily taken down.

I personally use them. It seems like someone is always throwing one away. Usually after the fabric on the edges starts to sun rot. Making a mess in your car. On the grow room walls. They work quite well.