Get Dupont Mylar from Lowe's or Home Depot. Rule of thumb is if you can see your hand through the other side dont get it. Hope that helps.
i happen tork at a dollar store. we ell a lot of balloons, including the mylar hliuk balloons.. anyone know if i got large square balloons and flipped them inside out would this work?
that is a brilliant idea but like weedman says if u can see your hand through the other side of it dont bother using it....im using kitchen foil. i know im not supposed too cos it may cook my plant but its workin a treat so far...as u can see in display pic
i use a space blanket i got in a first aid kit ... 6'x4' when fully unfolded, super reflective and thermal absorbing