i am waiting to see what quiltforme comes up with as an answer

If you are using lots of thread, then yes it would get heavier.

How funny, I was wondering the same thing LOL.

The air in between the layers makes it feel lighter. When it is quilted the air is not there. I am extropolating (my big word for today) from my lifesaving days when we had to pull out live people and weights for practice.

Too bad I didn't read thia a few hours ago....I just finished quilting a lap quilt for my MIL. I could have done the before and after weighing. :( Oh well..next time, if someone else doesn't beat me to it.

Patti