Why do I keep doing this?
 

I've had a quilt top that needed a border adding to it for quite some time now, and decided that today was the day. I had already decided that I needed to do a black border and thought that I didn't have any black fabric. I suddenly remembered today that I did in fact have a whole bunch of black fabric that I bought to make another quilt that I've been putting off for a while...so I grabbed it out of the bag and began making my borders...about halfway through I suddenly realised that I hadn't prewashed the black fabric! I carried on because at that point I didn't really fancy ripping out the stitches, and if I washed the cut pieces they would unravel and be too small...
So now I have a lovely looking quilt top with lovely borders...but I'm scared to wash it! The centre of the quilt is really bright, and I really don't want to ruin it!
Is this something that I can get around by using colour catchers? Is there some way I can soak it in the bathtub without it ruining the rest of the quilt top?
As the title suggests, this is not the first time I've made this mistake! When will I learn?!?

I don't pre wash fabrics. I use several color catchers each time I wash a new quilt, in case -- and most of the time there IS extra dye, which is caught by the color catchers. I don't dry a quilt until I've looked it over carefully to make sure that all is good and no spots. Have never had a problem. Someday that may change, but I've been quilting for nearly 40 years and before color catchers I'd throw in an old white t shirt or something else that's cotton, and that worked the same way.

I prewashed some blacks the other day and they ran a lot, color catchers were not the answer. I put the fabrics in a large sink with hot water and Retayne, then rinsed in cold, and that solved the problem. I did the same with a red and white finished quilt in the bathtub, since the red was running, and I had washed it several times before I put it in the quilt. Retayne in the tub might be the way to go if you are concerned.

Don't wash it until it is quilted. I don't prewash fabrics. Instead I take my finished quilt to the laundromat and wash it using Synthrapol in their largest front-loader. The large front-loader uses plenty of water to dilute any dye bleeds, and the Synthrapol suspends any loose dye particles so they dont' have a chance to settle into other fabrics. The key to this working well is to use a *lot* of water and Synthrapol in the water.

Do ***NOT*** use Retayne on a finished quilt! Retayne will permanently set any dye bleeds. Retayne is what you use on a bleeder fabric to get the bleeding to stop.

I've just had a little leftover scrappy soaking in a glass of water for 40 minutes and the water hasn't discoloured at all...so I'm thinking I might just get away with this one!
I will wait until I've quilted it before I wash it, and keep my fingers firmly crossed until then!

I don't prewash either. I did a black and white and gray Kona solid quilt and used several color catchers when I washed it. Didn't notice any running of the black.

I made my daughter the bom from the quilt show last year but did't prewash. I tested the red in hot water and it turned the water pink. I took it to the laundmat (i have a small frontloader) and put it in the oversized frontloader using warm water setting. I used 3 color catchers. No bleeding. Yea.

Use color catchers when the quilt is finished. You should be OK.

Retayne is only used when prewashing fabric as it will set the dye. You can use Synthrapol to help suspend any loose dye particles when washing the finished quilt for the first time or use lots of color catchers. I have also used original Dawn dishwashing soap with good results when prewashing wasnt an option.

I am really sad about your unfortunate and preventable misfortune. Wash the quilt with Retaine following the instructions.

It is a good thing that there are solutions for all the people who don't wash fabric before using it in their quilts.:D
peace