If you apply the high heat of an iron directly on top of your blanket, it could cause the inside material to melt. The only exception would be glass beads, but even these aren’t completely melt-proof. As the filler melts, it could also clump together and become a complete mess as it cools. From that point on, the weight wouldn’t be evenly distributed and the blanket would be rendered ineffective. This is where a duvet cover comes in handy. If you choose one made of cotton, then it’s easy and safe to iron before putting your blanket back inside of it. However, avoid ironing if your duvet cover is made from any of the following materials:
Polyester
Fleece
Mink