If the person recovered, the lesions gradually faded and did not form scars or scabs. After they break open, they form hard, thick, gray-yellow scabs, which sometimes leave scars. However, such scabs and redness usually heal within one or two weeks. Strikebreakers (called "scabs") were threatened and sometimes attacked. They cause powdery scabs and galls and disrupt growth. In China, powdered smallpox scabs were blown up the noses of the healthy. This is sometimes accomplished by the importation of replacement workers, strikebreakers or "scabs". This will loosen debris and remove dried scabs. Pustules, scabs, hyperpigmentation and feather loss may develop. Fresh scabs were more likely to lead to a full-blown infection. Shampooing is important to prevent scabs from forming around the hair shaft. After they break, they form yellow scabs. The technique used scabs that had been left to dry out for some time. The radicalized janitors invaded classrooms, accused the professors of being scabs, and demanded solidarite. Women also violently confronted "scabs", policemen, and soldiers.