What you have is Insul-brite, by the Warm Company. It has a metallic-looking coating on one side, which is actually a heat reflecting mylar.
We sell a lot of Insul-brite in our online store, and with each purchase we include an instruction sheet, which we developed in conjunction with Warm Company reps. Here is the relevant part, for your purposes, of the instructions:
Important Notes: When using in table runners or placemats, put the
silver side up. When using for potholders or oven mitts, put the silver
side toward the heat, and use an extra layer of cotton batting such as
Warm n’ Natural or Warm Tater under the Insulbrite to provide additional protection
to hand or table. Insul-brite is heat-resistant, not heat-proof!
When machine quilting with Insul-Brite, your needles may wear more
quickly and may break. To prevent this from happening, quilt
SLOWER than usual and have spare needles available!
We recommend, for the additional layer of cotton batting, Warm Tater batting, because it has no scrim and is thin enough not to add a lot of bulk to your project.