It SHRANK!!!!
 

I am making a quilt for my son-in-law which has shades of dark blue for half and ivory for the other half. I washed the jewel blue backing and it bled a lot. The quilt top is made of Layer Cakes so I experimented by putting two of the 10" dark blue into the washing machine along with the backing.
When I took them out of the dryer, I compared them to ones I had not washed. They shrank to 9" blocks. Now I do not know what to do. If I do not wash to cakes, the quilt will definitely shrink when laundered and be puckered. If I do wash the cakes, the pattern measurements will be off.
What should I do?

I wouldn't prewash. As I've mentioned before, fabrics on their own can shrink a *lot* when washed. However, once in a quilt that has moderate quilting, the quilting binds the fabrics to the batting and the batting becomes the controlling factor in shrinkage. In other words, after moderate quilting, the fabric shrinkage is limited by how much the batting shrinks.

Shrinkage can be a problem if the quilt is tied instead of quilted, or if the quilting lines are far apart (for example, the 10" maximum allowed by Warm and Natural). In these cases there is not enough quilting for the batting to control fabric shrinkage. With a normal amount of quilting, though, fabric shrinkage becomes a non-issue.

Since you've washed two of the 10" squares, I think you should wash the rest before sewing the quilt top. Otherwise the uneven dimensions will drive you crazy when you try to sew the pieces together.

Depending on how (un)evenly the other squares shrink, you might want to square them up to common dimensions before you begin sewing. I know this will be a pain-in-the-neck, but it will prevent much more serious and harder-to-correct problems later on.

Next time, you might do as Prism99 recommends: Don't prewash. Just post-wash once all the quilting is done (and the binding is attached).

But if you don't wash you will have the problem of the dark blue bleeding? (If it's the same fabric as the backing, possibly even if it's not?) It sounds like you will need to try to eliminate the bleeding without shrinking, which means not putting in the dryer or using hot water. Can you experiment with just soaking in cold water and see if you can control the bleeding that way? You certainly don't want the dark blue to continue bleeding on the white.

I agree with Prism99. I have made quilts with pre-cuts, which I never wash, and a backing which has been prewashed, and I have no issues with the finished product shrinking awkwardly. I do free motion quilt, and I would say that my quilting is moderate to heavy, which stabilizes the entire thing and limits the shrinkage.

For bleeding, I recommend washing the finished quilt in the largest front-loader at your local laundromat, using Synthrapol as your detergent. You want a machine that uses as much water as possible so that any dye bleed becomes highly diluted. You also want a detergent, such as Synthrapol, that suspends dye particles in the water so they don't settle into other fabrics.

You mentioned washing the blue fabric with the background fabric. Did the background fabric absorb any of the blue dye bleed? Some fabrics are resistant to dye bleeds and not affected by them.

Agree also w/prissm99. I have been surprised when I previously used relatively cheap cotton fabric and got very little shrinkage because it was moderately well quilted. I would not prewash but use some Shout Color Catcher on first wash after quilt completed. Cold wash gentle .

Okay here is another factor to consider--your batting. Warm and Natural will shrink about 4%. Poly batting will not shrink. Hobbs 80/20 will also shrink about 4%.

I always wet my fabrics with as hot a water as my hands can stand and dry in a hot dryer--to check for excessive colour bleeding and minimize shrinkage. But also because I do not care for the sizing that is in the fabric. It tends to inhibit my ability to breathe--which I think is sort of necessary for the whole continuance of life thing.

It depends on the look that you want your final laundered product to have--totally flat with no 'crinkling' or some to moderate 'crinkling'. The amount can be controlled by the denseness of the quilting and/or the choice of batting.

what is the brand/ line of fabric that is shrinking so much?

Everything I have read is NOT to wash any precut fabric.