Air Infiltration:
The amount of air leaking in & out of a building through cracks in
walls, windows & doors.
Annealing: In the manufacturing of
float glass, it is the process of controlled cooling done in a lehr
to prevent residual stresses in the glass. Re-annealing is the
process of removing objectionable stresses in glass by re-heating to
a suitable temperature followed by a controlled cooling.
Annealing Lehr: An on-line, controlled
heating/cooling apparatus located after the tin bath & before the
cooling conveyor of a float glass production line. It's purpose is
to relieve induced stress from the flat glass product to allow
normal cold end processing.
Argon: An inert, nontoxic gas used in
insulating windows to improve the insulating value of sealed glass
units.
Autoclave: A vessel that employs high
temperature & heat. In the glass industry, used to produce bond
between glass & PVB or urethane sheet, creating a laminated glass
product.
Bed or Bedding: In glazing, the bead of
compound or sealant applied between a lite of glass or panel and the
stationary stop of sight bar of the sash or frame. It is usually the
first bead of compound or sealant applied when setting glass or
panels.
Beveling: The process of edge finishing
flat glass to a bevel angle.
Borosilicate Glass: A high silicate
glass that has at least 5% boron oxide.
Bow (& Warp): A curve, bend or other
deviation from flatness in glass.
BTU: An abbreviation for British
Thermal Unit - the heat required to increase the temperature of one
pound of water one degree Fahrenheit.
Bubbles: In laminated glass, a gas
pocket in the interlayer material or between the glass & the
interlayer. In float glass, a gaseous inclusion greater than 1/32"
in diameter.
Buck: Wood frame surrounding a window
unit.
Bullet Resistant: A multiple lamination
of glass or glass and plastic designed to resist penetration from
medium-to-super-power small arms and high-power rifles.
Butt glazing: The installation of glass
products where the vertical glass edges are without structural
supporting mullions.
Caulk: The application of a sealant to
a joint, crack or crevice. A compound used for sealing that has
minimum joint movement capability; sometimes called low performance
sealant.
Chipped Edge: An imperfection due to
breakage of a small fragment from the cut edge of the glass .
Generally this is not serious except in heat absorbing glass.
Cullet: Broken glass, excess glass from
a previous melt, or edges trimmed off when cutting glass to size.
Cullet is an essential ingredient in the raw batch in glass-making
because it facilitates melting.
Condensation: The accumulation of water
vapor from the air's humidity on any cold surface whose temperature
is below the dew point, such as a cold window glass or frame that is
exposed to humid indoor air. Low conductivity or warm edge spacers
reduce condensation.
Curtain wall: An exterior building wall
which carries no roof or floor loads and consists entirely or
principally of metal or a combination of metal, glass, and other
surfacing materials supported by a metal frame.
Cut Sizes: Glass cut to specified width
& length.
Cutting: Scoring glass with a diamond,
steel wheel, or other hard alloy wheel & breaking it along the
score. Other methods of cutting glass include water jet & laser.
Deflection (center of glass): The
amount of bending movement of the center of the glass lite
perpendicular to the plane of the glass surface under an applied
load.
Distortion: Alteration of viewed images
caused by variations in glass flatness or inhomogeneous portions
within the glass. An inherent characteristic of heat-treated glass.
Double Glazing: Any use of 2 lites of
glass, separated by an air space, within an opening, to improve
insulation against heat transfer and/or sound transmission. In
insulation glass units, the air between the glass sheets is
thoroughly dried & the space is sealed, eliminating possible
condensation & providing superior insulating properties.,
Double strength: In float glass,
approximately 1/8" (3 mm) thick
Edgework: Grinding the edge of flat
glass to a desired shape or finish.
Egress Size: Make size of a window unit
that is sufficient to allow a minimum square foot sash opening to
meet BOA or local code requirements.
Elastometric: (adj) Having the property
of returning to it's original shape & position after removal of
load. (n) an elastic rubber-like substance.
Emissivity: The measure of a surface's
ability to emit long-wave infrared radiation.
Etch: To alter the surface of glass
with hydrofluoric acid or other caustic agents. Unintentional
permanent etching of glass may occur from alkali and other runoff
from surrounding building materials.
Facade (face): The whole exterior side
of a building that can be seen in one view. - usually the front.
Fenestration: Any glass panel, window,
door, curtain wall, or skylight unit on the exterior of a building.
Flat glass: A general term that
describes float glass, sheet glass, plate glass and rolled glass.
Float glass: Glass formed on a bath of
molten tin. The surface in contact with the tin is known as the tin
surface or tin side. The top surface is known as the atmosphere
surface or airside.
Flush glazing (pocket glazing): The
setting of a piece of glass or panel into a four-sided sash or frame
opening containing a recessed "U" shaped channel without removable
stop on three sides of the sash or frame and one channel with a
removable stop along the fourth side.
Frame Opening: The width & height
measurement in inches, of the opening into which the replacement
window will be installed.
Fully Tempered Glass: Flat or bent
glass that has been heat-treated to a high surface and/or edge
compression to meet the requirements of ASTM C1048, kind FT. Fully
tempered glass if broken will fracture into many small pieces (dice)
which are more or less cubical. Fully tempered glass is
approximately four times stronger than annealed glass of the same
thickness when exposed to uniform static pressure loads. Outside of
North America is is sometimes called "toughened glass".
Gas Filled Units: Insulating glass
units with a gas, other than air, in the air space to decrease the
unit's thermal conductivity (U-value) or to increase the unit's
sound insulating value. (i.e.: Argon)
Glass: A hard brittle substance,
usually transparent, made by fusing silicates, under high
temperatures, with soda, lime, etc.
Glass clad polycarbonate: One or more
pieces of flat glass bonded with an aliphatic urethane interlayer to
one or more sheets of extruded polycarbonate in a
pressure/temperature/vacuum laminating process.
Glazing: (n) A generic term used to
describe an infill material such as glass, panels, etc. (v) The
process of installing an infill material into a prepared opening in
windows, door panels, partitions, etc.
Grids: (also called Muttins or Grilles)
Colonial square & diamond patterns between the glass.
Heat Absorbing Glass: Glass that
absorbs an appreciable amount if solar energy.
Heat-resistant glass: Glass able to
withstand high thermal shock, generally because of a low coefficient
of expansion.
Heat-Strengthened Glass: Twice as
strong as annealed glass; therefore, it is able to resist slightly
stronger impacts. Produced in a similar manner to tempered glass
(slower cooling than tempered). Heat strengthened glass is not
considered safety glass & will not completely dice as will fully
tempered glass.
Heat Treated: Term used for both fully
tempered glass & heat-strengthened glass.
Insulated glass: unit Two or more
pieces of glass spaced apart and hermetically sealed to form a
single-glazed unit with an air space between the glass. (Commonly
called IG units.)
Interlayer: Any material used to bond 2
lites of glass and/or plastic together to form a laminate.
Jamb: Thickness of the wall from the
inside surface of the house to the outside surface of the house.
Laminated Glass: Constructed by bonding
a tough polyvinyl butyral (PVB) plastic interlayer between two
pieces of glass under heat and pressure to form a single piece. Can
be made of any kind of glass, but is most typically made of
annealed, heat-strengthened, or tempered glass.
Lehr: A long, tunnel-shaped oven for
annealing glass, usually by a continuous process.
Lite: Another term for a pane of glass
used in a window. Frequently spelled "light" in the industry, but
often spelled "lite" in text to avoid confusion with light as in
"visible light".
Low-Emittance (low-E) coating:
Microscopically thin, virtually invisible, metal or metallic oxide
layers deposited on a piece of glass and sealed in an insulating
glass unit to reduce the U-Factor. The radiant energy (heat), i.e.
long wave infrared, is in effect reradiated back toward its source.
Make Size: The tip-to-tip width &
height measurement in inches of the finished window.
Mica: Mica is fire proof, infusible,
incombustible and non- flammable and can resist temperatures of
600-C to 900-C,depending on the type of mica. It has low heat
conductivity, excellent thermal stability and may be exposed to high
temperatures without noticeable effect.
Mullion: A horizontal or vertical
member that supports and holds such items as panels, glass, sash, or
sections of a curtain wall.
Muntin: Horizontal or vertical bars
that divide the sash frame into smaller lites of glass. Muntins are
smaller in dimensions & weight than mullions.
Obscure Glass: (see patterned glass)
Oriel: A double hung window unit made
with one with one sash larger than the other.
Patterned glass: One type of rolled
glass having a pattern impressed on one or both sides. Used
extensively for light control, bath enclosures and decorative
glazing. Sometimes called "rolled", "figured" or "obscure" glass.
Picture Window: Window unit with a
stationary sash that does not operate.
Polished Wire Glass: Wired glass that
has been ground & polished on both surfaces.
Primer: A coating specifically designed
to enhance the adhesion of sealant systems to certain surfaces, to
form a barrier to prevent migration of components, or to seal a
porous substrate.
Projection: The distance that a bay,
bow or garden window extends outward. Measured from the exterior of
the building to the furthest extension of the window.
Reflective Glass: Glass with a metallic
coating to reduce solar heat gain.
Rolled glass: Glass formed by rolling,
including patterned and wired glass.
Rough Opening: The opening in a wall in
which a window or door is to be installed.
Rub: A series of small scratches in
glass generally caused during transport by a chip lodged between 2
lites.
R-value: The thermal resistance of a
glazing system expressed ft2/hr/oF/Btu (m2/W/oC). The R-value is the
reciprocal of the U-value. The higher the R-value, the less heat is
transmitted throughout the glazing material.
Sandblasted Finish: A surface treatment
for flat glass obtained by spraying the glass with hard particles to
roughen one or both surfaces of the glass.
Sash: The portion of the window that
holds the glazing, usually the portion of the window that operates.
Score: To penetrate the surface of a
lite of glass by means of a cutting device, e.g. a cutter, along a
predetermined line in order to produce a lite of glass of a specific
size and/or shape.
Scratches: Any marking or tearing of
the surface appearing as though it had been done by either a sharp
or rough instrument.
Seeds: Minute bubbles in float glass less than 1/32" in diameter.
Slider Window: A horizontally opening
window. In a 2 section - has 2 operable sash. 3 section has 1
stationary & 2 operable sash.
Sloped Glazing: Any installation of
glass that is at a slope of 15 degrees or more from vertical.
Solar Control Glass: Tinted and/or
coated glass that reduces the amount of solar heat gain transmitted
through a glazed product.
Spandrel: The panel (s) of a wall
located between vision areas of windows which conceal structural
columns, floors, and shear walls.
Storm door: A panel or sash door placed
on the outside of an existing door to provide additional protection
from the elements.
Storm window: A glazed panel or sash
placed on the inside or outside of an existing sash or window as
additional protection against the elements.
Tempered glass: Flat or bent glass that
has been heat-treated to a high surface and/or edge compression to
meet the requirements of ASTM C 1048, kind FT. Fully tempered glass,
if broken, will fracture into many small pieces (dice) which are
more or less cubical. Fully tempered glass is approximately four
times stronger than annealed glass of the same thickness when
exposed to uniform static pressure loads.
Tinted glass: Glass with colorants
added to the basic glass batch that gives the glass color, as well
as, light and heat-reducing capabilities.
Transmittance: The ability of the glass
to pass light and/or heat, usually expressed in percentages (visible
transmittance, thermal transmittance, etc.)
Transom Window: Window unit with a
stationary sash, usually installed over a door.
U-Factor (U-Value): A measure of the
rate of non-solar heat loss or gain through a material or assembly.
The lower the U-Factor, the greater a window's resistance to heat
flow and the better its insulating values.
United inches: Total of the width &
height of the frame opening expressed in full inches..
Weather-stripping: A material or device
used to seal the opening between sash and/or sash and frame.
Weeps (or Weep Holes): Drain holes or
slots in the sash or framing member to prevent accumulation of
condensation & water.
Window Unit: A non-load bearing device
to fill a hole in a wall, consisting of both frame & sash members.
Wire glass: Rolled glass with a layer
of meshed or stranded wire completely imbedded. Available as
polished glass and patterned glass. Approved polished wired glass is
used as transparent or translucent fire protection rated glazing. .
The wire restrains the fragments from falling out of the frame when
broken. Note, building codes & guidelines involving the use of
wire glass have changed in recent years and fire resistant products
are not available.
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1440 Carbon St.
Reading, PA 19601
610-372-7868
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