Different Types of Glass This article contains information on all the
different types of glass, including Ordinary Sheet Glass, Float Glass, Energy
Efficient Glass, Self Cleaning Glass, Patterned Glass, Toughened Safety Glass,
Laminated Glass, Wired Glass, Mirrors and Picture Frame Glass.
More glass information can be found in our
Glass Regulations and Glass Safety section and photos of glass samples can be found in our
Library.Ordinary Sheet Glass This glass is made by passing the molten glass through rollers; this
process gives an almost flat finish but the effects of the rollers upon the
molten glass makes some distortion inevitable. The glass can be used in domestic
windows etc. but the relatively low cost of float glass (with its lack of
distortion) has tended to restrict ordinary sheet glass to glazing greenhouses
and garden sheds where the visual distortions do not matter. Sheet glass can be
cut a glass cutter and no special equipment is necessary. The glass is often
available in standard sizes to suit 'standard' glasshouses, these sizes tend to
be comparatively cheaper than glass cut to size.
Float Glass (Plate) Float glass gets its name from the method of production used to
manufacture it. The molten glass is 'floated' onto a bed of molten tin - this
produces a glass which is flat and distortion free.
Float glass can be cut using a glass cutter and no special equipment is
necessary. Float glass is suitable for fixed and opening windows above waist
Energy Efficient Glass Some manufacturers produce float glass with a special thin coating on one
side which, allows the suns energy to pass through in one direction while
reducing the thermal transfer the other way. The principle behind this is the
difference in thermal wavelength of energy transmitted from the sun and that
transmitted from the heat within a room. The special coating often gives a very
slight brown or grey tint to the glass. The coating is not very robust and would
not last very long if subjected to normal cleaning or external weather
conditions - for these reasons, this type of glass is normally only used in
sealed double (or triple) glazed units with the special coating on the inside.
Self Cleaning Glass Some manufacturers produce float glass with a special thin 'photocatalytic'
coating on one side. This coating uses the ultraviolet rays from the sun to
steadily break down any organic dirt on the surface using the photocatalytic
effect and thus loosen the dirt from the glass. Self–cleaning glass also has
'hydrophilic' properties which means that when rain runs down the pane of glass,
it will wash away the dirt previously loosened. Together, the 'photocatalytic'
and 'hydrophilic' effects allow the glass to stay cleaner for a longer period
than untreated glass. Small particles of dirt will loosen and (providing there
is rain) be washed off fairly quickly, however, bird droppings and other large
bits of dirt, will take longer to be cleaned off. Self cleaning glass may, from
time to time, need additional cleaning and great care needs to be taken with
such cleaning to avoid damaging the surface coating - never use any abrasive
cleaner, check with the particular manufacturer for detailed guidelines. If
additional cleaning is carried out, the self-cleaning properties may take a
period of time to become active again.
Patterned (Obscured Glass) Made from flat glass, this type has a design rolled onto one side during
manufacture. It can be used for decorative effect and/or to provide privacy.
Patterned glass is available in a range of coloured tints as well as plain. A
variety of pattern designs are available, each pattern normally has an quoted
distortion number, from 1 to 5, 1 being very little distortion, 5 being a high
level of diffusion. On external glazing, the patterned side is usually on the
inside so that atmospheric dirt can easily be removed from the relatively flat
Toughened (Safety Glass) Toughened glass is produced by applying a special treatment to ordinary
float glass after it has been cut to size and finished. The treatment involves
heating the glass so that it begins to soften (about 620 degrees C) and then
rapidly cooling it. This produces a glass which, if broken, breaks into small
pieces without sharp edges. The treatment does increase the surface tension of
the glass which can cause it to 'explode' if broken; this is more a dramatic
effect than hazardous. It is important to note that the treatment must be
applied only after all cutting and processing has been completed, as once
'toughened', any attempt to cut the glass will cause it to shatter. Toughened
glass is ideal for glazed doors, low level windows (for safety) and for
tabletops (where it can withstand high temperature associated with cooking pots
Laminated Glass As the name suggests, laminated glass is made up of a sandwich of two or
more sheets of glass (or plastic), bonded together by a flexible, normally
transparent material. If the glass is cracked or broken, the flexible material
is designed to hold the glass fragments in place. The glass used can be any of
the other basic types (float, toughened, wired etc.) and they retain their
original breaking properties. Some laminated glass is laminated for other
reasons than just keeping any broken glass in place, some provide decorative
internal finishes to the glass while others act as fire breaks.
Wired glass incorporates a wire mesh (usually about 10mm spacing) in the middle
of the glass. Should be glass crack or break, the wire tends to hold the glass
together. It is ideal for roofing in such areas as a garage or conservatory
where its 'industrial' look is not too unattractive. Wired glass is generally
not considered a Safety glass as the glass still breaks with sharp edges. Wired
glass is available as clear or obscured.
Mirrors are usually made from float glass 4-6mm thick, and silvered on one side.
Mirrors are available for use without a surrounding frame, these usually are
made from a type of safety glass. Old mirrors, and modern mirrors supplied
within a frame, should not be used unframed as any damage to them might cause
the glass to shatter dangerously.
Picture Frame Glass
Glass (and plastics) are available specifically for picture framing, these tend
to be referred to as 'diffused reflection' glass or plastic. They have high
transparency but low reflective properties to reduce reflections when the
picture or photograph is viewed.
Most of these materials can easily be cut by the average diy person providing
suitable tools and safety precautions are taken.