“Indigenous people of those areas were the first to notice that the liquid would gradually harden and turn black on exposure to air.”

“Of course, she would read what he had written, and in his words find that which would harden her against the trials to come.”

“She juggled three jobs to pay for an overseas adventure that would harden her to the battles she would later have in business.”

“As this mesh dries, it hardens and forms a scab to protect the wound as it heals.”

“It's flexible polymer clay that hardens into rigid plastic after a spell in your kitchen oven.”

“When paint can get into the adobe, then it hardens in there, and it makes it cling better than anything.”