We sometimes get tiny flecks of foil with some colors that want to stick to the WB Discharge ink. I don't believe those flecks survive the first trip through the laundry, but I'm not 100% positive on that.
I don't like it, but it doesn't always happen and not a single custy has complained. (Weird)
Currently my bases are CCI D-Base Premium and D-White. Pigments are a mix of CCI and Matsui. I'm also interested in the answer to this problem.