GlassCatalogue_LowRes

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