Most at-home kits come with a dye applicator and one pair of gloves. Says Errett, "Within 10 minutes, the women stopped using the applicator and started running the product through their hair with their hands"—wearing the gloves, which they then no longer had for the rinse.
Give them two pairs of gloves, and make them stylish for good measure.
Coloring instructions are dense and confusing. "Every single woman looked at the instructions for 30 seconds and then threw them away—even the women who had never [dyed their hair at home] before."
Present things clearly. "We put the instructions on the box and kept them very simple: five easy steps, illustrations, large print."
Hair dye stains everything, from skin to hardwood floors. "Most of these women are sitting in their bathroom for 35 minutes because they're petrified it's going to spatter all over the place."
Thicker dye, plus a "blocking cream" for the hairline, cleaning wipes, and a shower cap to keep color where it belongs.
A version of this article appeared in the March 2014 issue of Fast Company magazine.