I am finishing up on a string quilt using about 40 different black and white print fabrics. I did prewash the ones with a black background and got some very dark grey color catchers, so there was a fair amount of bleeding from some of the fabrics. I would recommend you at least prewash the blacks.

I think peace of mind is worth more than anything, even crinkling. It will crinkle more over time. I would wash both-the black for bleeding, and the white just so that everything has had a chance to shrink once. And , you never know where those fabrics have been. I like to start them with them clean-clean and having given them the color catcher treatment.

Why take the chance? Prewash!

Ditto!!!!!!

Maybe you should try prerub/ presoak test.
I do this sometimes when i am worried but really don't want to wash.
First, i rub a corner of the fabric with a soft white rag to see if color "rubs" off. For sure if it rubs off it will bleed off.
Then, I put a little laundry soap and really hot water in an old container i keep....and add a 4" square of fabric. If it bleeds when i swish it around a bit - i wash it....if not, i roll the dice and use it without washing first. Then use color catchers in the wash.
Also -- i always fill the washing machine at least half full before adding my quilt.

I wash everything washable ( except the thread) before cutting it.

I have had some blacks add some strange colors to the soaking water.

If you want a crinkly look - leave the batting unwashed and the you will get the same amoint of shrinkage over the entire piece.

This is the technique that I was taught by Harriet Hargrave. I usually only do with with fabric that I feel might be a bleeder. I never pre-wash. I always use color catchers and never have had a problem. I would use Hobbs 80/20 instead of W&N. It is a bit fluffier and not give you the flat look at W&N will give the look of the quilt.

Thanks, I've only made about 8 quilts, all with W&W and none very crinkly.

I appreciate the advice from people who have done black and white quilts specifically, since I'm guessing the black could really show up on the white if it bleeds.

I bought a bunch of batik fabric for another bed-size quilt and sewed the seams and washed it all, but did not dry it. I had some dark purple in there as well as almost white blue so I didn't want bleeding in that quilt either. I wasn't as worried about the crink because I'm using it to embroider in the hoop quilt. I'm adding wool batting under the stitching for tarpunto look.

No one has answered if I would get more shrinkage that way.

I am doing a DWR with Kona black as the background. I had to wash it 5 times before it stopped bleeding. 1st wash I did with Retayne. 2nd wash I did with just soap and water. 3rd wash I did with vinegar. 4th wash I did with Retayne. 5th wash my color catcher came out white.

Wow, did it ruin the whites or did it all come out?