the shrinkage has more to do with the batting and the density of quilting than it does with the actual fabrics- the way to avoid that problem with table clothes/toppers is to skip the batting- or use a layer of muslin or pre-washed flannel for batting.
if you want to pre-wash a pre-cut i would use a net bag- and do it on gentle- figure on sitting for awhile ironing- each and every one will be a crumpled little mess- you will have to smooth and press...i never pre-wash pre-cuts- i only use them for projects that i'm not worried about shrinkage- or bleeding color.
i do pre-wash most yardage.
but it is the batting that causes most shrinkage surprises in finished quilted projects. :thumbup:

This thread is indirectly related ... and may add some Food for Thought on this subject!
http://www.quiltingboard.com/t-122370-1.htm

thanks for the link and everyone's comments

I have only used charm packs one time... It was for a crazy 9 patch class (and the only quilting class I ever had also). It was great to have a nice color combination and not have to cut. But I found I had to do a LOT of squaring of the blocks when I put it together and I was not real happy with the finished quilt after I washed it. Then this week, I needed a few coordinated pieces to try a new pattern so I pulled out 4 of these unwashed charm squares left from that project. I noticed right away that some of them were not square. I had to trim a full 1/8" from one corner on one of them.

So not only possible shrinkage, but possibly the charm squares aren't square. I am not sure I'd buy them again though that was not the context of this thread.

I heed your point except in this case I didn't use any batting being it was on my dining room table and I wanted to set candlesticks etc on it. Now it's relegated to the kitchen table. lol Thank you all for the suggestions. I appreciate the advise!!

Width shrinks more than length I believe. So, when you have unwashed charm squares, the shrinkage could be very odd in the finished project I would imagine. I pretty much wash everything first for this reason. I've avoided the issue with the packets as I don't use them or kits much for this reason and for the extra $s they cost. I've had real problems using some precut fabrics in sampler classes too.

Think I would really wet them good with water or starch and steam press them. Then when I'd sew, I'd then treat every 'shorted side' of the square as being a scant cut I guess, if that makes sense. That's not very practical but I've been forced into worse I guess. BTW, one thing I've always hated with kits: Borders cut from the width of the original fabric that results in sometimes wavy borders for my project. I just don't understand why they can't be cut from the length of their yardage for these kits! After all, they are preparing numerous kits at a time and aren't like the individual quilter who has to think more than twice about buyin the extra fabric!
OK, here's Mary Ann getting off her soap box now...

Wouldn't it just be faster to buy yardage, wash, dry and cut it into squares? All this swishing and squaring and fraying sounds like a lot of work to me.

You are so correct...and that is what I do now after having so much shrinkage on the precuts.

Patti

I prewash mine by just putting them in my bathroom sink in hot water sqeeze water out lay on my ironing board to dry the iron when still damp a lot of them will bleed and somrtimes I will have to do that three times

It is almost impossible to wash them, as then you have all sizes. I do not wash before sewing. I sew my project, then I buy a nice piece of clear plastic (the little heavier kind) and put it over my beautiful table cloth. If I use place mats to match they go under the plastic also. No muss no fuss. Just wipe clean after your meal. Hope this helps you, it has been a Blessing to me. And saved many a beautiful items.
Have a Blessed day
Ellen