I've read about baked potato sacks and have always thought that it just didn't add up... turns out I was right. All the directions out there that use pre-quilted fabric, embroidery, polyester... even cotton batting are a fire hazard. If you have made, or plan on making baked potato sacks for gift giving please be sure to read this article.
The Warm Company has created a new "Warm Tater" batting just for this purpose. I did not find this batting locally or at Joann's.com but it's a new product. I'm sure as word of the product spreads so will the availability of the product. It may even be a worthy investment for those quilts that I read about on Facebook being warmed in microwaves .. not that I am endorsing warming a blanket of any form in a microwave. If warming all fabrics was a safe proposition we wouldn't have burn tests to find the content of fabric... we wouldn't use flames to singe the ends of webbing strips when we make bags... Bottom line... think twice before you heat up fabrics with intense heat sources.