I've seen muslin in every fabric store I've ever been in - I've never bought any. Now I'm working on a quilt where the list of materials calls for muslin for the pieced top.

Most of the muslin I've looked at appears thin and loosely woven -- almost like broadcloth. I'm rather leary about using muslin in a top along with "better" fabrics.

So - what defines muslin? Is it similar to broadcloth? Is it special in some way?

I've done a little searching on the board and members mention Kona brand and bleached and unbleached, so I know it's not a brand or color. Board members also commented on how much it shrinks -- but it's not unbrushed flannel, is it?

Muslin is usually a lightweight natural or white(bleached)
cotton fabric.
it is not flannel and does shrink
but it depends on the brand
even a joanns they have several diffent weights and it all says muslin
I find that the best is the wide backing muslin
it is usually of a better quality than the 36 or 45 inch

I have found it to be in many weights too..
I just hold it up to the light until I find a nice weight to use :D:D:D

i have used muslin in a quilt along with other material and it looks great!!! you will notice that some muslin seems to be better than others , i buy mine at jo anns

Look at all the different muslins available like at Joann's. You will be able to tell the better quality ones by the thickness of the weave. Hold them up to the light and the less that you can see through them, the better.

Rangefinder muslin is really good quality

I've used muslin in quilts and as long as you prewash there's no problems. It looks great especially if you're making a 30's 49's, Civil War, antique repo, etc. For those you wouldn't want to use anything else since that's about the only thing available back then that would have been used as the whites or off whites in quilts.

ok - so there is nothing special about it? My pattern could just have well listed x yards of solid beige and I would have bought Kona solid beige and called it a day?

The quilt I have in mind is an antique reproduction - so muslin gives a more authentic look?

Muslin will definately give it a more authentic look.

What you call muslin we here in Ireland call calico. I use it a lot especially for handsewing Cathedral Windows. I can manipulate it and it is so soft to work with. It must be prewashed as it does shrink.