I hear ya. I paper toweled everything around the stove excessively and had a wash station ready for drips.. but it wasn't needed. The dye won't take to anything stainless but I also used this roaster successfully too.
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I poked a pinhole into the protective seal under the cap of the dye bottle and wrapped a paper towel around as it was the only part of the process that had potential for mistakes. Once diluted it's so weak that you really need not worry. Food coloring would do more damage. By the second time around I used a tiny 2.5 inch high stainless pot. A pretty nice one that had me nervous. But no splatter and no ring in the pot. The recommended temperature produces a simmer, not a splashing boil, no cover needed. I used a meat thermometer, (which might be aluminum?), and it also did not stain. I used salad tongs to place and remove the pieces without splashing. Rinsed my pieces in a clean white kitchen sink without a problem. I was far more destructive wasting all those paper towels than anything else. But I wouldn't push it with your wife. I would find a hotplate.