All custom-made hearing aids and earmolds are made from a “cast” of the ear. The cast is referred to as an ear impression. The hearing professional makes the ear impression in the office. It takes about 10 to 15 minutes. The audiologist looks in the ear first to make sure it is sufficiently clear of earwax. They then place a special cotton or foam block in the ear canal to protect the eardrum, and then a soft silicone material is placed in the ear canal. When the material hardens (about 5 to 10 minutes later) the silicone cast and the block are removed from the ear canal. Often, the ear canal will be slightly oily after the impression is removed. This is normal. The oil comes from the impression material and prevents the material from sticking to the skin.
Tell the audiologist before the ear impression is obtained if you are allergic to plastic or dyes.