I have dyed with Wilton. Just be aware that cake dye often “splits” out into 2 or more colors. I’ve yet to find a lavender that didn’t split out into fuschia and some blue too. And my greens sometimes split out to blue too. I like many of the effects, tho, so I use cake dyd preffy often. I find it colorfast on wool.
Also I have a pink cake dye (Cake Create) that I just love, but I would only use it on loose fiber that is to be carded, because no matter how hard I try, the fist bit into the water really takes the dye - at such a rate that by the time the top is in, it doesn’t get any. But by the time I’ve carded it, it evens out, and I love the finished color. I call it “bubble gum” and it is very popular with young ladies.
For dyeing with Wiltons or food coloring, you can use vinegar as a mordant either by soaking the yarn to be dyed in vinegar and water before dyeing, or adding vinegar to the wilton/food coloring & water (or both!)
Black really splits out! Especially if you immerse the fiber/yarn slowly into the pot.