Prism99

Depending on the manufacturing process, some fabrics pick up color more easily than others.

Instead of color catchers, I use Synthrapol for the first washing of a quilt, using hot water and a large front-loader at the laundromat. Color catchers do not necessarily catch all loose dye particles, especially if there is fabric in the mix that is also good at picking up loose dye. Synthrapol suspends loose dye particles in the water, preventing them from being picked up by fabrics. It won't necessarily protect against a perpetual "bleeder" fabric, but for normal excess dyes in fabrics it has always worked for me.

In my opinion, your best bet is to wash again using Synthrapol and lots of hot water. The dye particles that have settled into your Moda Snow are not permanently set. Permanent setting usually requires a chemical manufacturing process. Although some dyes are heat set, the heat in a domestic dryer is typically not high enough to permanently set dyes. Synthrapol will work at lifting those unset dye particles as well as keeping them suspended in the water to be rinsed away. It can take multiple washings with Synthrapol and hot water to get rid of all the dye bleeds, but it usually works eventually.

What kind of washing machine did you use? Bleeding issues are worse in domestic front loaders because they use so little water. When you have a large dye bleed, such as with backing fabric, there will not be enough water to dilute the bleed. Again, this is why I use a large laundromat front loader for the first wash. Aside from the Synthrapol and hot water, just the fact that there is more water in that first wash helps keep dye bleeds diluted and less likely to be picked up by fabric.

Edit: Most loose dye is caused by the manufacturer not rinsing the fabric well enough. There is excess, loose dye left in the fabric that comes out in the first wash. The occasional perpetual bleeder fabric is caused by a different manufacturing problem, this time with improper setting of the dye. Perhaps the right mix of chemicals wasn't used, or the heat was too low or heat cycle too short. Most likely your backing fabric simply had excess dye in it.

Regarding the Moda Snow, fabrics are not necessarily treated to resist picking up loose dye. A fabric that has not needed to undergo any dying process will be manufactured differently than a fabric that has had a color design transferred to it. The manufacturing steps will be different, and likely the processes needed to secure the colored design to a fabric will also stop the fabric from picking up loose dye.