Batik question
 

I am getting ready to start a quilt using Batik layer cake squares. Is it necessary to prewash these pieces before I start ?

I will be the first to admit that I don't usually pre-wash my fabric but after a discussion here on the board re batik's and running/bleeding - I was about to start a quilt using batiks for the first time - OK I thought I will wash (by hand) and see what happens - am I glad I did - I couldn't believe how much colour came out and the number of times I had to wash to get the water to run clear. So I would suggest that, at least with batik fabric, it should be pre-washed.

precuts are (generally) not pre-washed- but if the colors are deep/saturated you might want to at least color test them before using- (wet- rub with paper towel/piece of muslin-if color comes off you have a bleeder & may want to wash it)
the problem with pre-washing pre-cuts is the distortion/shrinkage- you may start with 10" squares and have something else after- but it boils down to your choice- there are some people who pre-wash every single fabric they purchase (& tend to stay away from pre-cuts) and there are those who prewash nothing....
the pattern you are using may also play a role in the decision- if you need accurate 10" squares you may not want to pre-wash- if cutting them up & have some *fudge-room* it won't matter so much...but at least test for color run

If you want to prewash a layer cake do it by hand not in the washer. I don't wash precuts but use a few color catchers when I wash the quilt after it is complete.

Like katier I don't prewash and use color catchers too when washing after it's complete.

Unless you're mixing dark colors with white it just isn't a problem and even then it would only be a problem if you somehow managed to set a dye run on the white. Just because there are unset dyes doesn't mean it's a problem.

The Bali Batik by Hoffman are prewashed thru the process before being pre-cut. The ones i would be more concerned are the batik that come from India. You would knowdest the fabric a lot different and dye seems to bleed a lot more.

If you wash, They might not be the size you need