Because wool has natural fire resistant properties- it won’t melt, it won’t burn and it retains heat well. Because it is heat resistant it pushes the heat back into your item. That’s why we say it “irons both sides at the same time". The result is very flat quilt blocks and seams.
It holds heat and steam like a brick oven
The heat goes all the way through the fibers. It's not necessary to use steam.
You usually don’t need to use starch, but if you do, the wool pressing mat is felted so it can be easily cleaned by running under cool water and letting it dry.
It creates a nice, flat stable surface
The mats are ½” thick and a tightly packed 100% felted wool. This allows to have a nice stable flat surface to iron on.
Your items stay put, no sliding
It does 'grab' your blocks and patches as you press—a really big help when you're pressing blocks into submission. You can line up an edge of your block with your fingers and give a bit of a tug as you pull it square while pressing. Your items won’t slip like they do on a traditional ironing board and it does all this without pinning. No distortion will happen to your blocks as they stay in place while pressing.
You can pin into the mat though if you need to hold your item down for whatever reason.
