Glassary - T

Taffeta™:

Pilkington Taffeta™ is the brand name for one of the Pilkington Texture Glass™ range (see consumer leaflet Pilkington Texture Glass™) of patterned glass. Pilkington Taffeta™ has an obscuration level of 3.

TEC Glass™:
Pilkington TEC Glass™ is an on-line coated glass for the Refrigeration and white goods industries. The product is designed to reflect heat back into ovens and to reduce frosting on refrigerated display cabinets.

Tempered glass:
another name for toughened glass.

Template:
an exact size physical model of the shape of the glass to be manufactured.

Textured glass:
depending on context this can either be:

  • a patterned glass, one of Pilkington Texture Glass™ range or
  • Pilkington Pyroshield™ Textured or Pilkington Pyroshield™ Textured Safety


Thermal break:
a gap or a portion of low thermal conductivity in a metal frame, separating the inner and outer parts of the frame, designed to increase the thermal insulation of the frame.

Thermal comfort:
the physical feeling of comfort in relation to the absence of cold radiation and down draughts from window surfaces of insulating glass units with low U value. See also Technical Bulletin Glass and Energy Management – Thermal Insulation.

Thermal fracture:
a phenomenon where glass is broken by the heat of the sun. See thermal stress and thermal safety. See Technical Bulletin Glass and Thermal Safety.

Thermal insulation:
the ability to restrict the flow of heat. The lower the U value, the better the insulation.

Thermal properties:
depending on the context this could mean either:

  • the U value, or
  • the solar properties, or
  • both of the above


Thermal safety:
the determination of whether annealed glass is thermally safe, given that it has good quality edges. If a glass is not thermally safe it is necessary to use toughened glass instead. See Technical Bulletin Glass and Thermal Safety.

Thermal Stress:
stress developed in glass due to difference in temperature across its surface. In buildings, this is commonly related to glass exposed to the sun, where the central part is heated, but the edges, in the frame, remain relatively cool. Too high a temperature difference can result in thermal fracture of the glass. See Technical Bulletin Glass and Thermal Safety.

Thermal transmittance:
an alternative term for U value.

Thermally safe:
has a risk of thermal fracture sufficiently low to be acceptable. See Technical Bulletin Glass and Thermal Safety.

Thirdoctaveband:
a range of sound frequencies that is 1/3 of an octaveband. (Note that this is not a numerical 1/3. For example, the octaveband from 200 to 400Hz is split at 250 and 320Hz.) See Technical Bulletin Glass and Noise Control.

Thirdoctaveband centre frequency:
the frequency commonly used by sound engineers to ascribe the average loudness or sound insulation over that thirdoctaveband. See Technical Bulletin Glass and Noise Control.

Tight size:
the size of the opening in frame into which glass is to be glazed. The glass should be smaller than the tight size, to allow a suitable edge clearance.

Time/temperature curve:
the prescribed temperature rise in a fire test furnace as a function of the duration of the BS 476 test. See Technical Bulletin Glass and Fire.

Tinted float:
float glass that has small amounts of metal oxides added during the melting process to colour it and give it solar control properties. Sometimes called body-tinted float, the product was called Pilkington Antisun ™ but is now known as Pilkington Optifloat™ Tinted. See Product Data Pilkington Optifloat™ Tinted.

Tinted interlayer:
a coloured interlayer in laminated glass, which is tinted to give the glass solar control properties. The tints for PVB laminated glass are described by 4-figure code; the first two digits refer to the colour, the second pair, the amount of light transmission through the vinyl (the light transmission will fall the amount will depend on thickness of glass). The code numbers for the tinted interlayers produced by our sites as at 11/00 are listed below. As there are different vinyl manufacturers it is recommended that glass be supplied from one source to ensure tint matching.

Pilkington Plyglass – Alfreton:
3065 – white, 65% vinyl light transmission – sometimes called white diffused
5042 – grey, 42% vinyl light transmission
4055 – light brown, 55% vinyl light transmission
6028 – medium brown, 42% vinyl light transmission
8009 – dark brown, 9% vinyl light transmission, sometimes called shadowlite

Pilkington Leeds:
3065 – white, 65% vinyl light transmission – sometimes called white diffused
3655 – brown, 55% vinyl light transmission – sometimes called light brown
3628 – brown, 28% vinyl light transmission – sometimes called mid brown


The following are old reference numbers that are not currently manufactured but might still come up in specification

3609 – brown, 9% vinyl light transmission – sometimes called dark brown or shadowlite
3773 – blue/green, 73% vinyl light transmission
2165 – white, 65% vinyl light transmission – sometimes called white diffused
5538 – bronze, 38% vinyl light transmission
M60 – 6.8mm laminated consisting of 2 layers of 3609 interlayer – sometimes also called double shadowlite

It is possible to tint the resin used in cast-in-place laminated. However this is extremely susceptible to colour inconsistencies from sheet to sheet and batch to batch. The cast-in-place method is not recommended where any consistency of colour is required

Total shading coefficient:
see shading coefficients.

Total solar energy transmittance:
an alternative term for total solar heat transmittance.

Total solar heat transmittance:
the proportion of incident solar radiation transmitted by the glass, including both the solar direct transmittance and a portion of the absorbed radiation which is re-radiated, expressed as a fraction. (See solar properties).

Total transmittance:
an alternative term for total solar heat transmittance.

Toughened glass:
glass which has been heated past its softening point and chilled rapidly to build in a surface compressive stress which gives it greatly increased strength and makes it break into small fragments if broken. See Product Data Sheet Pilkington Toughened Safety Glass.

Traffic noise reduction index (RTRA):
is derived by taking into account a typical spectrum of road traffic noise (see acoustic properties). Also Technical Bulletin Glass and Noise Control.

Translucent:
letting light through, but obscuring clear vision.

Transmission:
an alternative word for transmittance, expressed as a percentage.

Transmittance:
the proportion of incident light or solar radiation transmitted by the glass, expressed as a fraction. (See optical properties and solar properties).

Transom:
a horizontal bar across an opening. Often used to refer to a window that is attached to the bar. Derived from Latin "transtrum" meaning a crossbar.


Transparent:
allowing through vision.

Triple glazing:
an alternative name for insulating glass units comprising three panes of glass.

T.S.C.:
total shading coefficient.

T.S.H.T.:
total solar heat transmittance.