The Mosaic Palette is an amazing device. It allows you to print in 4 colors instead of 1, opening up a world of possibilities. There are still quite limited offerings on thingiverse for Multiple Color STLs, but the list is growing every day, and you always have the choice to use Meshmixer, and turn an existing single color object into a multi colored one.
My palette was fully calibrated and printing well, but I noticed an odd behavior. When transitioning from strong colors (e.g. black / blue), to weak colors (e.g. white / pink), no matter how much transition length I added (I even tried the max, 230mm), I would still get color bleeds. That means my hot end was not entirely purging!
I am using an E3D Lite6, which supposedly has a very short melt zone, and that should help reduce the amount of waste filament you print on the waste tower. But in my case, I was getting these bleeds:
Asking for advice on Facebook proved quite helpful. Members pointed out that very likely my Teflon tube was not fully inserted. I had recently replaced my regular PTFE with the Capricorn XS, and sure enough, there was a small gap when I took the hot end apart:
After re-seating the tube, problem resolved, and I was able to reduce my transition length a LOT, from the standard 130mm to about 100mm for strong colors, and 80mm for weak colors.