EZ, on the Colorants settling...use a small tool, something that won't scratch...stir the Colorant in the bottom of the bottle, but be very careful because that Pigment (powder) gets settled/hard-packed pretty good and takes a bit of pressure to loosen. I have a box of 100 Stainless Nuts, 5/16". One Nut gets dropped into each bottle of Colorant when it's initially opened. If You're not using a Nut or Ball Bearing, or something similar, You're not stirring the Colorant fully.
The Liquid Colorants in Pearl Colors have some issues of hard-packing, of course due to the Pearl Powder...but the Standard Colorant's Pigment is much finer-grained, and can settle even harder than the Pearls...the Fluorescent Colorants seem to be the worst. I mixed my Fluorescent Chartreuse (non-X2) a little while back, with a Stainless Spatula that I use for Rod Building Epoxy...I had some dense paste on the end of the Spatula, about like Cold Peanut Butter, but Chartreuse. Scrape that Paste back into the bottle and keep scraping the bottom of the bottle...get it good. This is where the Nut/Ball Bearing comes in. Close the bottle when You feel You've got the settling loosened, then shake...shake until Your arm hurts, then switch hands...keep shaking it, like You would a can of spray paint...keep it well shaken. If a bottle has been sitting awhile, check it good, then shake it even better. A well-shaken bottle of colorant will bring much better consistency from the first drop to the last drop...batch to batch.
When You first grab a given bottle of color and start shaking it, listen to the nut/bearing...it'll tell You where the settling/packing is.