Yes that is the question. After cutting out some squares for a wall quilt I found some fabric that would go well for sashing. All the other fabric (batiks)were washed but the sashing fabric was not. It was a black ish fabric and I almost didn't wash it. But I am from the old school of wash all fabrics before use ...so I did AND I am so glad I did. I bled terribly. I rinsed and rinsed to get the water to run reasonably clear.
Yep, I am so glad I listened to my inner voice. Wash before using..... :)

Good for you!! Never hurts to follow that inner voice, does it?

Glad to hear you had a happy ending, listening to your inner self :D:D:D

You might try using a color catcher when you wash your fabrics. If I have reds or blacks, I always throw in a couple for good measure. You can also use white vinegar in the wash. It's good for permanently setting the color into the fabric so it will no longer bleed. And your fabric does not come out of the wash smelling vinegary.

Do those work? Color catchers? I have used vinegar.

how much vinegar???

I always was a washer, then since using charm packs, I got away from it. Yesterday I watched a 2 1/2 by 8 1/4 strip shrink in front of my eyes as I pressed it with steam. I think I will go back to prewashing.

Color catchers only do what the name implies, they catch excess dyes from bleeding on other fabrics. They do NOT stop a bleeder from bleeding not do they set dyes. Unset dyes will continue to bleed and if you ever forget to use the color catcher with the bleeder, even if it has been washed with a color catcher before, it will bleed and run on to other fabrics.

Vinegar will not work with many of the modern dyes. Your best and safest bet is to use Retayne dye fixative when you do your initial prewash. You can buy it on line at Dharma trading and many LQS carry it.

Another prewasher here. I always prewash all of my fabric. The worst of the shrinkage happens from the heat of the dryer but the moist heat is important. I always "over dry" to make sure I get as much of the shrinkage out as possible.

For the vinegar, I use a quarter cup in my front loader. I used half a cup in a full load top loader. I go through a fair bit of vinegar with my laundry in general too. It helps keep less than stable colours like black and red looking new when you use it in every (or most) washes. It also will take musty smells out like if a damp towel got wadded up and forgotten for a while. Also helps keep your whites really white without giving them a yellow bleach tinge.

Tara

Someone gave me a quilt and I would have thought that she would have washed the fabrics. Wrong! I decided to wash it today and fortunately, I put into 2 color catchers. Lucky for me, I decided to check if they were picking up a red dye. Sure enough, the 2 color catchers were already a light pink when I checked. I then added 8 more, the rest of the box. After the wash, the color catchers were almost a dark red. My quilt was saved! I guess it might be a good idea to add them to every quilt wash, even though the fabric has been washed. I need to buy another box!