i do it all the time and have not had a problem...i keep reading about people here having their poly batting melt from ironing fabric with it in...but in 10 years i have never had this happen...i iron/press LOTS the only difference between what i do and what i've read from others is the steam....i never put water in my iron, i use a spray bottle of water...but other than not using steam i really don't know why there seems to be so much poly batting melting. i always fuse my labels on then i hand stitch around them...have never had a flat / melted/ hard area on a quilt. if you are worried about it maybe make a little sandwich from your scraps and use your fusable and see what happens. and yes, when i do iron it flattens...that's what ironing does...but then when it's washed and dried it fluffs right back up just beautifully