I'm afraid I belong to the wash it before you use it club. I will add fabric to my laundry to wash and if I don't have a full load, I wash and rinse the fabric in the sink. I've been surprised when some of the darker fabrics did not bleed, but there was one medium green that I had to wash out 3-4 times because it bled so much and it was from a LQS, so you never know.

Fabrics were dyed with acid dye in your (our) mother's day and vinegar did work at that time. Today's fabrics are dyed with fiber-reactive dyes and vinegar has absolutely no effect at all on them. Neither does salt. It is chemically impossible for them to work. Sorry. :o

I have had fairly good luck with batiks. I use the color catchers tho when I wash.

I don't usually prewash my fabrics. I just use color catchers when I wash them and it works well.

I never pre wash and I use mostly Batiks. If I remember I throw in a couple of color catchers. So far everything has been fine.

Interesting, I've only had one fabric discolor my machine. And it wasn't a batik, it was a seasonal (harvest) print from Jo-Ann Fabrics. It was the orange that rubbed off. The quilt is a UFO and hasn't been washed yet. Color-catchers ready and waiting!

I prewash all of my new fabrics simply because I never know what is going to go with what. If one piece shrinks 3% and another shrinks 5%, my quilt block becomes wonky. I also want to make sure nothing bleeds. It's amazing what color catchers catch!

It's true that vinegar (or salt) no longer works on the colors in fabric. However, if you want to make sure a quilt is washed clean of soap (soap attracts dust/dirt, and makes the quilt get dirtier faster) add a cup of white vinegar to the rinse water. Also, you aren't supposed to use fabric softener on a quilt for the same reason; it attracts dust/dirt etc. But the vinegar will act as a natural fabric softener. If I'm washing a quilt, I will often do 1 rinse with vinegar, and then another with just water. Probably overkill, but it helps here in the desert with all the dust around.

I've not had problems with my batiks. They have been of all sorts from WM jelly rolls to very nice LQS yardage. Not to say the next one I come across might not give me fits. Lol! Now every piece of denim fabric or clothing I've ever had is another story entirely. . .

I was firmly in the no-pre-wash camp, mostly because I think limp fabric is much harder to work with. But I decided to wash my batiks (took 3 afternoons with the ironing), and something in the orange/gold range bled on each of the washloads. I did use a color catcher, but stopped at just the one warm wash/rinse cycle. The good ones ironed up pretty much like new. I never expect a finely woven fabric to shrink, and this has been my experience. The cruder, heavier batiks will shrink like any other loosly woven fabric.