The vacuum tube in a CRT can implode if it is broken or punctured. The surrounding air will rush violently into the unsealed vacuum in the CRT, spraying broken glass in every direction. Color CRTs may contain mercury or other potentially toxic materials.
Instructions. Build a hearth for a fireplace that is 16 inches deep, according to This Old House writer Harry Sawyers. This is the standard requirement for municipalities and homeowner associations. The hearth should also extend a minimum of eight inches on either side of the fireplace.
A hearth is a brick-or stone-lined fireplace or stove that is often used for cooking. A hearth can also be defined as the stone or brick floor of a fireplace. hearth is a brick-or stone-lined fireplace or stove that is often used for cooking. A hearth can also be defined as the brick or stone floor of a fireplace. It sometimes extends onto the floor of a room.