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Glossary Of Terms / P-R

Glossary Of Terms / P-R Profile The profile of sash material is the side view or outline of the material. Putty A compound used to glaze and seal glass into joinery. Air-hardening type of glazing materials, usually oil-based. Pyrolytic Applied at high temperature. In relation to glass this describes coatings on line when the ribbon of float glass is around 550 degrees C. Gives a hard durable coating. Pyroshield Polished wired plate glass manufactured by Pilkington. Refer to Polished Georgian Wired. Radiation Depending on the context; either one of the methods of heat transfer, or electro-magnetic radiation, or one of the forms that heat from a fire gets through glass. Rebate The part of a frame in joinery which is designed to receive glass. The glass can be face putty glazed or receive a removable glazing bead to hold the panel of glass in place. Reflective glass Glass with a reflective coating which reflects light or heat. Refractive index When light or heat waves hit a piece of glass, some might be reflected, but some may go through the glass.Usually the waves which go through the glass will change speed, and this change in speed causes the light or heat waves to bend and change direction. The refractive index measures how much the waves ‘bend’. Reglazing The repair or replacement of glazing because of breakage, renovation or for any other reason. Relative heat gain (RHG) Relative heat gain is the combined effect of shading coefficient (SC) and U-Value (UV). The lower the relative heat gain value, the more efficient the glass is in restricting heat gain. It describes how much energy penetrates the building through the windows as a result of solar radiation. This is measured in watts per square metre. RHG = (SC x 637) + (U x 7.8) RHG can be expressed as both metric and imperial units. To convert W/m 2 to Btu/hr ft 2 divide by 3.154. 1 W/m 2 = 0.317 BTU/ft 2 1 W/m 2 .K = 0.176 BTU/hr/ft 2 /°F 242 Product Catalogue For Glass Processors & IG Manufacturers

Glossary Of Terms / R Exterior Interior Exterior Interior Heat Heat Without coating With coating Reflective glass with and without reflective coating. Relative humidity The percentage relationship between the actual amount of water vapour in a given volume of air at a specific temperature, and the maximum amount of water that would be present if the air were saturated with water vapour at a specific temperature. Reveal lining The trim member that lines the perimeter of a window between the frame and the internal wall lining. Also known as a reveal. Rolled glass Glass formed by rolling, including patterned glass and wired glass. (See Patterned Glass). Roller hearth furnace A process that supports the glass horizontally on rollers. From loading rollers the glass passes into a heating chamber and then into a cooling chamber. Roller wave distortion When the glass is in the heating chamber of the roller hearth furnace it can slump slightly. Waviness imparted on the glass produces distortion when the glass is viewed in reflection. Round and polish The grinding in the form of a semicircle and polishing, of the cut edge of the glass. Also known as round smooth. Ground to bullnose and polished Email: | Web: 243