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.
The Wood-Fired Oven Floor. Twenty to 27 inches is a good size to the oven floor, but to determine your exact needs make a mock-up of what you want to bake and calculate how much space it takes. Make your oven floor by setting standard red or fire bricks on a level bed of smooth, tamped sand, 4 to 6 inches deep.ext, cover it with a layer of mud 3 to 4 inches thick. To maintain an even thickness, use the width of your hand as a gauge, maintain a clean, square edge on the layer as it arches up and over the form, and angle the top of the mud layer inwards as you go up (see diagram in the image gallery).