How is tayammum performed? What are the things that invalidate tayammum?
Tayammum is the ritual cleansing performed in the form of wiping the face and both arms with clean soil or something of the type of soil in order to remove the state of ritual impurity such as not being in the state of minor or major ablution when there is no water or it is not possible to use the water available. It is performed by touching hands on clean soil or something of the type of soil and wipingover face and both arms with these hands.
It is stated in the Holy Qur’an, “But if you are ill or on a journey or one of you comes from the place of relieving himself or you have contacted women and do not find water, then seek clean earth and wipe over your faces and hands with it.” (Nisa, 4/43; Ma’idah, 5/6).
The person who is going to perform tayammum makes intention for which type of ritual purification he will perform tayammum (for minor ablution or ghusl). He strikes his hands on a clean soil or something of the type of soil as his fingers are separated from each other, moves his hands back and forth, raises and shakes them off smoothly. He wipes over his entire face with their palms once. Then he strikes his hands on soil again and wipes over right lower arm to the elbow by using the palm of his left hand; then he wipes over his left lower arm to the elbow similarly by using the palm of his right hand.
The things that invalidate ablution also invalidate tayammum. Moreover, tayammum is invalidated when the excuses that allow one to perform tayammum, such as finding enough water for ablution or ghusl, recovery from a disease, and having the possibility to use water, end (Mawsili, al-Ikhtiyar, I, 86).
Source: Presidency Of Religious Affairs The Turkey, High Board of Religious Affairs FATWAS