Something to think about. Never did it.

I also use my steam iron as I don't have anywhere to lay out the entire batting for a few days. Steam works really well.

The quilting spray also seems to help flatten the wrinkles. - Cynthia

My sister does this also. And she has to go up and down the steps to do it!

Sure helps get those wrinkles out!

I generally open up the batting and leave it on a bed or table for a day.
Next day, when I spread it out on the fabric, I 'spread' it with my longest ruler -- just like butter on bread. A teacher I know always did it and it seems to take out the wrinkles and bumps and I have never had any bunch or stretch.
Mary

A thought just came into my head. Are any of these cotton or bamboo batting come from China? I heard about the bedbug problem in clothing so I wonder if we should steam them before using them to make sure. Just a thought.

Donna Jean is right on! Even though no one told me about this in a book or class, I did it on my own. Pressing COMPRESSES the batting while steamin removes the wrinkles, buckles and waves, restores it closer to even thickness and helps realign the sides into a regular shape.

What I do is place the batting on the table, with a towel underneath, and then put the backing on top. Then I iron. This works even with Poly batting.
After I am sure it is lying nice and flat, then I do the traditional clamping and layering.
It works for me

Yes, I lightly steam press mine before I use it.

Never, always hand wash unless poly, roll in a large bed sheet and lay flat to dry that usually fixes most creases.

see sharonschamber.com video re sandwiching, it changed my life!