How can a chair stained with menstrual blood be purified so that one can sit on it with peace of mind?

If the blood that stained the chair is a small amount, it is excused. If the impurity is not excusable, then the method of purifying the chair, like other furniture, is by washing the contaminated area. Impure objects are not purified by the sun or by drying, except for the earth and what is connected to it, according to some scholars. Impurity does not transfer from one object to another if both are dry.