Originally Posted by
Girlfriend
Sometimes, on heirloom quilts that have been washed a lot, you can see the batting clumping together.
The key word here is "heirloom". What kind of batting is inside these heirloom quilts? Back in the day, they oftentimes used what was available. Sometimes, especially in the South, quilters carded their own cotton to use in quilts, and I wouldn't doubt that that kind of batting would clump.
I think you'll be fine with today's commercially produced battings, as long as you quilt per the package recommendations.