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Also, there are several previous posts on this topic you might want to read. In some of them Prism99 mentions Synthropol requires hot water to be fully effective and lots of water as it keeps the dye suspended in the water. Some say they use it and color catchers. If you do get some bleeding, do Not put it in the dryer as that may set the bleeding dyes. Instead wash it again with Synthropol, color catchers or both as the bleeding dye can still be washed out at this point. I only wanted to wash on cold water and just used color catchers and luckily didn't have bleeders.
Don't prewash. If you are concerned about the dye running use a color catcher. Batik is made with really hot water so it should not shrink.
Anna Quilts
I make a lot of batik quilts, many with strips/layer cakes that have not been prewashed. I wash the finished quilt with 2-3 color catchers and have never had a problem.
You want to finish the quilt before washing, as the quilting will hold everything together. Soaking a top is extremely risky. For one thing, you do not want multiple fabrics soaking in water; if one of them bleeds, there is plenty of time for the other fabrics to absorb the loose dye. Also, fabrics shrink at different rates; you can end up with a massively distorted top which you can never get to lie flat again without tucks and wrinkles.
The first wash of the quilt is important if there is a risk of dye bleeds. The most foolproof method is to use Synthrapol with a ***lot*** of hot water. Synthrapol suspends loose dye particles in the water so they can be rinsed away instead of settling into other fabrics. You still need a lot of water to dilute any dye bleed as much as possible. Most domestic front-loading washers do not use enough water. I take mine to the local laundromat and use their largest front-loader (can handle up to a king size). Never let a damp quilt sit before drying; the fabric-to-fabric contact while damp will promote movement of dye. Remove immediately from washer and either toss in dryer or lay flat (with fans to speed drying if done indoors).
Synthrapol is often sold in quilt shops, especially those that cater to dyers. It is also widely available online:
http://www.amazon.com/Craft-Synthrap...dp/B000YZ3UHQ/
I have started playing with batiksand really love their ability to blend with each other no matter what the color. So far washing in cold water and a few color catchers has worked extremely well for me. If there was any bleeding, it just blended in with the rest of the quilt and I didn't see it!
I use batiks almost exclusively. I never prewash. I use all colors and mix them with white etc. I throw in some color catchers and haven't had any issues with bleeding. I alway check it to make sure before I put it in the dryer. Good luck.
when I give a quilt to someone I always tell them to use 4 or 5 color catchers to make sure the colors don't bleed. I don't prewash anything. I have always heard if you wash some of the fabric that you need to wash all of it, as it won't shrink the same when washed. I have washed fininshed colors in color catchers and I have very good luck.
Just to be clear, color catchers do not prevent bleeds; they soak up bleeds. Also, they are meant for light bleeds. If you have a heavy bleeder fabric in the mix, color catchers can be overwhelmed and not able to catch all of the loose dye. Probably the safest first wash is a combination of Synthrapol and color catchers; however, Synthrapol requires hot water to be fully effective.
Most modern fabrics do not bleed a whole lot, but it's still possible to buy a bleeder fabric. There are two types of bleeder fabric -- one that is oversaturated with dye, and one which never had the dye properly set during the manufacturing process.
For the first type, the bleeding will eventually stop as the excess dye is finally rinsed out of the fabric. Fibers can absorb only a finite amount of dye; if the manufacturer has not thoroughly rinsed the fabric after dying, excess dye particles remain in the fabric until the user rinses it all out.
The second type is probably more rare. When the dye is not properly set, the fabric can continue to bleed indefinitely. First wash will release the most loose dye into the water, but subsequent washings will continue to release dye. When there is not a lot of dye being released into the water, color catchers are sufficient to absorb the particles. However, the color catchers again can absorb only a finite number of loose dye particles. A bleeder fabric can release a *lot* of dye the first time it is exposed to water.