Marcie's Caramel Corn

My friend Marcie used to make this in college for Sigma!

6 quarts popped corn
2 cups light brown sugar
1/2 cup white corn syrup
1/2 lb butter
pinch of cream of tartar

Keep popcorn in warm oven on low
Boil rest of ingredients for 5 mins
Pour over warm popcorn in large pans
Place in oven at 150 degrees for 1 hr
Stir every 15 mins
Cool and store in airtight containers or ziplock