Theatre Catalog (1947-48)

wall filled with the substance will stop the passage of fire for one hour. Insulation manufactured from cotton, wood, and other vegetable fibers must be chemically treated to resist fire. Needless to say, fire-resistance is of utmost importance in a theatre or any other place of public assembly. There are numerous cases on record where flames upon reaching mineral wool insulation have been stopped completely or slowed to such an extent that the blaze could be extinguished with comparatively slight damage. The substance is recognized by the administrators of many building codes as an effective firebarrier and a movement is now under way to obtain lower insurance premium rates for buildings propertly insulated with mineral wool. Mineral wool is the most widely used product for thermal insulation, according to the Bureau of Mines, which states, “Generally, mineral materials are preferable because of their resistance to fire, electrical short-circuits, moisture, termites, *vermin, and decay.” Theatres in extremely cold sections of INSTALLED IN A THEATRE, mineral wool presents, before decorative materials are overlaid, the aspect shown at the right. Below, granular mineral wool insulation is being blown to full thickness into f roof. Such insulation reduces operating costs of heating and cooling systems. 1947-48 THEATRE CATALOG the area above a theatre Canada have reported that, where it formerly was impossible to raise the auditorium temperature above 56 degrees with the most intense firing, after insulating the ceiling with mineral wool it was possible to keep the entire auditorium at 70 degrees in 20-below weather with only a pound and a half of steam. Conversely, air-conditioned theatres have reported that, after insulating, it was necessary to operate the cooling equipment only intermittently with a resulting large saving in cooling costs. Many houses, unable to obtain air-cooling equipment, have installed insulation and found that temperatures were lowered as much as 15 degrees on hottest summer days. Mineral wool is made by melting the raw ingredients to a liquid state and then drawn from the furnace in a tiny stream. This is broken into minute drops by a high-pressure steam jet propelled through the air. As the blowing process proceeds, fine threads are formed and fall in a fluffy mass. This woollike substance is then rolled into small pellets for blowing into walls and ceil GRANULAR MINERAL WOOL, used in theatre work, is packed and weighed (above). In this form, the material can be blown into walls and ceilings of any theatre without causing disruption. At the left is seen the removal of the wool bats from the finshing machine. This form also has theatre use. ings and fabricated into the paper-backed batts and blankets. The substance consists of fine, interlaced mineral fibers having the appearance of loose wool, and the term mineral wool is a generic appellation covering several similar products, differing chiefly by the raw materials from which they are made. “Reck wool” is made from natural rock or from combinations of various natural minerals or rocks, such as limestone and shale. “Slag wool” is made from the blast-furnace slag produced in smelting iron, copper, or lead. “Glass wool” is made from silica sand, soda ash, and limestone, with or without scrap glass, and other materials. All types of mineral wool have virtually the same insulating and fire-resistant properties, Cost of insulation is not excessive and most building owners find that it pays for itself in fuel savings within three years. An existing structure can be insulated with mineral wool today at a cost no greater than in 1936, due to improved methods of manufacture and application. 169