I only pre-washed one top and I did not expect the outcome and will not do it again. Always quilt first.

Yup, I've had that disaster happen too. Washed a top and all the seam allowances frayed and some frayed so much the seams were open! I managed to repair it and had to quilt it with serpentine stitch over all the seams, to hold them together. Ugh. Never again.

I would wash (actually - just flush the afflicted areas) if there was something really gross on it that had to be removed such as blood, vomit, urine, food and beverage stains

The handling grime ( in my world that includes starch/sizing and glue basting pruducts ) can wait until the item is finished to be washed out.

I am in tbe group that washes all washable components before using them in an item. This includes trims like rickrack, bias tape,, and zippers.. uneven shrinkage annoys me.

I did that exactly one time- never again! What a mess.

I realize this is a really old thread, but I'll post my experience here anyway in hopes it might help someone else in the future.

I washed an unquilted top once because I discovered one of the fabrics was going to bleed, but I did it very carefully and was successful. Here's how I did it:
I filled my top-loading washer with hot water, added a tablespoon of Dawn, put the top in. After the machine was done filling but before it could start agitating, I pulled the plug and let it sit overnight (12 hours). The next day I plugged the machine back in, hit the cancel button, then set it on a rinse-and-spin cycle. The quilt top was never agitated. It drained and spun "dry" (damp). I laid it out on my living room floor to air dry. The bleed was permanently fixed, the back of the top had no stringy nests or mess, I was a happy quilter!
p.s. LOVE my Speed Queen.

In January, I quilted three tops for my SIL, whose grandmother had made them. Someone down through the years decided they needed washing and ohmigosh, what a disaster. I had balls of frayed thread, split seams to repair and fabric so fragile that they would probably never withstand another laundering.

None of them were square or anything close to it - but I started the one that was the best made about eight years ago and then gave up until this year.

At New Year's, I dragged them out and finished repairing the damage that I could. I used pre-shrunk flannel for "batting" so that if my SIL ever decided to wash them, the flannel could help support the fragile tops.

I quilted the heck out of all of them, got them bound and then took them to her, with notes about where to find instructions for washing antique quilts, especially the most fragile one. I couldn't accept the responsibility of washing them, myself.

The quilting and binding had improved them a lot and I was happy knowing that I had done everything I could do.

I won't ever do it again, though! 😄

Good idea. I would have to do the soaking in the bathtub and then just do a rinse/spin cycle with this new washer of mine, but at least I could do it. I'm glad you kept it from bleeding!

I did that once - washed the top before quilting. Popped a bunch of seams. Never again!