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Glass

Glass has been described as "the greatest building material known to man" and it is a building material with outstanding durability, which plays a crucial part in creating the visual appearance of all buildings.

Understanding glass and its relationship to light, transparency, reflection, insulation, solar gain, sound control, strength, safety and what these qualities can bring to a building to impact on indoor and outdoor environments is critical when designing with glass.

Whilst all float glass is imported into New Zealand, local processing is available for some products, so for specific design projects there is the opportunity to get exactly the glass performance you need for your building glazing solution without compromise, from a range of local and international manufacturers and processors.

Clear Float (annealed)

The Float glass process is the most common process of glass production. The process involves the melting of the raw ingredients in a furnace and floating it on a large bed of molten tin. The mixture slowly solidifies over the tin as it enters the annealing oven where it is slowly control cooled. The glass exits the cooling process as one large sheet when it is cut to meet the customer's needs. The speed at which the glass is drawn over the tin bath controls the thickness which ranges from 3 to 19mm.

 

Low Iron (extra clear)

The main ingredient of glass is silica which has naturally occurring iron oxides and it is these oxides that cause the greenish tint you can see in most butt jointed structurally glazed situations such as total vision systems, shop windows, showers, glass cabinets etc. Low iron glass is made from a high quality silica which is almost iron oxide free, offering a clearer glass allowing much higher light transmission. All other finishing processes are the same as standard float glass.

 

Tinted

Tinted glass is manufactured by the same process as clear float glass, however manufacturers can introduce oxides to tint the glass in a range of shades, typically green, blue, grey and bronze, and they reduce UV, visible light transmission and solar gain.

When a glass has a tint it can get hot and create thermal stress based on the colour and darkness of tint the glass may require heat treatment. Tinted glass can provide significant benefits when used in IGUs and in conjunction with a Low E coated glass.

 

Coated

Float glass can be coated on the float line with pyrolytic coatings (hard coating) or off line with sputtered coatings (soft coatings) and the coatings are transparent and can be reflective for solar control and/or low E for insulation.

 

Reflective

Reflective glass is designed to reflect solar heat and light and reduce glare and solar gain in a building – There is a wide range of reflective glass types and colours and properties vary widely.

 

Low E

Low emissivity glass (Low E) is a special coating that is designed to increase the thermal performance of windows and reduce heat transfer. In simple term it is like a "transparent tin foil". The pyrolytic coatings can be used in single glazing, but Low E coatings are best applied to surface 2 or 3 of an IGU and used in conjunction with a tinted glass to assist in reducing solar gain.

 

Toughened Safety Glass (TSG)

  Also known as tempered glass, it is a Grade A Safety Glass that is easily identifiable in its broken state by its characteristic small dice sized particles of glass which significantly reduce the risk of injury. Toughened glass must have all its finishing work eg, holes, chamfers and polishing undertaken prior to the process of toughening being undertaken. The toughening process involves heating of the glass to a very high temperature and then, rapid cooling by blasting air on the surface to create high compression stress in the glass surface and tensile stress in the centre. The additional stress imposed in the glass creates increased thermal and mechanical strength. Toughened glass is susceptible to Nickle Sulphide Inclusions (NiS) which may cause spontaneous fracture of the glass. Therefore any safety glass installed overhead or as a barrier should be heat soaked and or laminated so it remains in the frame and has a second layer of glass as a contingency.

 

Heat Soaked Toughened Safety Glass (QTSG)

Heat Soaking is an additional destructive testing process that follows the toughening process and is aimed at detecting impurities in the glass like Nickle Sulphide Inclusions.  The Heat Soak process heats the glass slowly up to a moderately high temperature and slowly cools it again, and if the glass has an inclusion or other fault in it, this process generally causes the glass to fail. It is a safe guard process to ensure that any toughened glass that is being used as a life safety barrier or could be installed overhead does not fail in service. The process does still not offer a 100% defect free certification.

 

Heat Strengthened (HS)

  Similar to the toughening process, although the glass is heated to slightly lower temperatures and has less air quench meaning the glass has lesser surface compression stress. It does not fracture in the same fashion as toughened glass, and is not a safety glass, but as it will generally break from side to side and the glass will remain in the frame after breakage. Due to the heat strengthening process this glass is still very stable to thermal stress and is most commonly used in tinted glass, and coated glass where it may be partially exposed to large temperature differentials in façades vision or spandrel panels which are susceptible to large internal heat gains. There is a significantly reduced risk of this type of glass having NiS failures. This is a common form of glass processing for curtainwalls for both the vision and spandrel area.

 

Ceramic Frit

Ceramic Enamel glass is often known as "fritted" glass as it uses crushed glass frit mixed with special enamel paint and colour oxides that are fired onto the glass surfaces during heat treatment process. The ceramic enamel is applied by rolling, spraying, screen printing or digital printing and is very stable in colour and durable.

The pattern or design can be solely for aesthetic purposes or can aid in privacy screening, providing solar shading or reducing glare.

Direct on glass digital printing allows for virtually any image in multiple colour, to be printed on glass for interior and external glass applications.

 

Laminated Safety Glass (LSG)

Is a Grade A Safety Glass and provides increased safety because it holds together if broken reducing the likelihood of serious injury, whether in a vertical or overhead situation. It can also offer increased security as the glass will generally often remain in the frame if impacted. Laminated glass consists of two or more layers of glass, factory bonded together with plastic interlayer.  Laminated glass is available in a range of interlayers and the most common being;

  • Polyvinyl Butyral (PVB) – This is the most common form of interlayer and is available in 0.38, 0.76, 1.1 and 1.52 mm thickness, but can be layered thicker.
  • Cast in place (CIP) resin – There are two types of resin interlayer used, Safety and Acoustic, which provides better sound control. The resins are UV cured between glass layers which are separated by a clear edge tap
  • Ethylene Vinyl Acetated (EVA) – This is a newer interlayer which is available in 0.4, 0.8, 1.2, 1.6 mm thickness and can be layered thicker. It is ideal for laminating a range of special products including inserts in the laminate.
  • SentryGlas Plus (SGP) – This is a special high strength interlayer for barriers and structural glazing applications, which is more rigid than other interlayers.

Laminated glass can also assist in a reduction in noise transfer through the glass and lowered UV transmission.  Laminated glass can be incorporated with other glass types in an IGU to provide a further increase in thermal performance.

Laminated glass has size limitations depending on the process but Woods Glass has access to some of the largest lamination manufacturing sizes available.

PVB is available in various tints and colours including translucent, and EVA can be laminated with coloured PET inserts and or translucent interlayer.

Laminated glass can incorporate layers of toughened glass (TLSG) and Heat Strengthened glass (HSLSG) for additional strength and safety.

 

Insulating Glass Unit (IGU)

An IGU has two or more panes of glass factory sealed with an air or gas space between, and is often known as Double Glazing (DG).

Since single glass has poor thermal resistance - by adding the airgap the insulation value increases significantly by eliminating heat transfer. An IGU works to insulate in both winter and summer conditions and reduce the cost of heating and cooling in buildings. The measurement of thermal performance is known as the U-Value, and this can range from 3 down to 1 W/m2k depending on the air space and glass type.

The glass layers can be high performance low E glass, which reduces the U value. Because the IGU is sealed it can also be filled with inert gas such as argon to increase thermal performances.

IGUs provide many advantages to a building's envelope: reduced heat loss, heat gain, condensation, reduced noise and potentially reduced mechanical plant - and above all, increased occupant comfort.

 

Cast U-Profile (LINIT)

Cast or profiled glass is one of the oldest methods of glass production, and it is made while the glass is still hot and in a plastic state as is rolled and bent into various width moulded 'U' shape profiles up to 7m long, then cooled, annealed and cut to length. The resulting glass channels all have an individual optical character which gives the effect of a lively, light refracting glass façade. The U-profile channels can have multiple surface finishes, including cord and prismasolar patterns, sandblasted or ceramic frit (coloured). Linit U-Glass can also be made in low iron glass and can be toughened and heat soaked.

Originally channel glass was a low cost solution for simple commercial and industrial buildings, however it has become a fashionable building element that is now specified by leading architects for museums, hospitals, shopping centres and sport stadiums etc.

There are many methods of installing these glass elements, including a unique glazing channel system. We will help specify the appropriate product based on your design.

Woods Glass source this glass from 'Lamberts' one of the oldest independent glass manufacturing facilities in Germany, established in 1887. Woods Glass represent the Linit glass (profiled cast glass) products in New Zealand and are available for providing design and engineering assistance for this specialist glass and the integration of it into your project.

Product Features

  • Made in Germany.
  • Available up to 7m long.
  • Range of profiles available from 232 x 41 -331 x 60mm
  • Can be toughened (tempered) and heat soaked
  • Range of surfaces finishes and patterns
  • Range of colours using ceramic enamel
  • Range of glazing methods for single or double glazing
  • Sustainably produced using oxygen fired melting furnace.
  • Utilises the maximum amount of recycled glass possible.
  • Labelled as one of the 'Top 10 Green Building Products 2008' and was the only glass product in the list.
  • High quality product.
  • Range of frames available including thermally broken

From the Download section you can download the Linit Design Manual or click here.

 

Bends & Curves

Glass can be bent and curved in a simple radius or compound curves. It can also be toughened and laminated for safety and made into an IGU for insulation. Limits apply to all process depending on the equipment used and as a guide the following apply

  • Annealed
  • Toughened
  • Laminated
  • Insulating IGU

 Woods Glass can source bends and curves from local and international manufacturers depending on the specification.

The key terms and data required are;

Height:

The straight edge length of the bend

Girth:

The distance around the circumference of the curve

Depth:

The distance between the apex of a bend and a line across the edge

Radius:

A line taken from the centre of a circle to the circumference

Degree: 

The size of the segment of a circle in degrees

Tangent:

A straight line coming from the arch of a curve

Chord: 

The straight distance between the edges of the curve

 

 

Fire Rated

It is important to understand that glass is not fire rated, rather it is used in conjunctions with a frame system to achieve a Fire Resistant Rating (FRR). The frame can be timber, mild steel, stainless steel or even special aluminium profiles.

The FRR has 3 classifications from NZS 4232 Part 2 – Structural/Integrity/Insulation and each are defined in minutes as follows FRR = 30/60/30

Typically glass is only defined by Integrity and Insulation for example - /60/30.

Fire Rated glass products vary from traditional wired glass to special ceramics, intumescent laminates and IGUs and up to -/120/120 performance

Woods Glass and Thermosash Commercial can assist with the supply of Fire Rated systems

 

Anti-Reflection (AR)

Normal glass surfaces have an external reflection of 8% and these can impede the view, especially in high angle of incidence (viewing on an angle). To assist the clarity of the view AR glass has a special surface coating that reduces the reflection down to 1% or less and a miracle happens as the glass looks like it disappears. AR glass is ideal for display cases, special shopfronts and viewing windows. The coating can be applied to one or two surfaces and AR glass can be laminated, toughened and used in an IGU. AR coating can also be applied to low iron glass for higher clarity.

 

Self-Cleaning

Self-cleaning glass is float glass with a special pyrolytic coating which works in two stages. Firstly the coating reacts with UV light to generate a photocatalytic process that loosens and breaks down organic dirt particles on the surface of the glass. Secondly, when rain lands on the glass, the water is attracted to the surface by the hydrophilic properties, causing it to sheet evenly across the glass, washing away loose dirt and drying without spotting.  Obviously the glass must have full sun and rain exposure and not be shaded by structure or the like. It’s ideal for hard to clean surfaces such as rooflights and canopies but does not like salt water deposits so it not great near the sea.

 

Translucent

 

Translucent glass can be created with a variety of techniques as follows

  • Sand blasted – Using a sand to blast the glass surface white
  • Acid etched – Using acid baths to etch the surface white
  • Translucent interlayer – using PVB or EVA translucent interlayers in varying density
  • Translucent ceramic frit – using translucent ink and in combination with white to make a range of translucent glass
  • Translucent inserts - Using special material inserts and films in EVA laminated glass

Translucent glass can be combined with colour for special effects

 

Patterned

Patterned and obscure glass is manufactured in many different thicknesses and patterns. The pattern is rolled into the surface during manufacture and over time many patterned designs used for housing are no longer available.  Typically they are 4, 5 and 6 mm in thickness but some special commercial patterns are available in 8 and 10mm. In addition some are available in grey and bronze tints.

Typical pattern are

  • Stippolite / Spotswood
  • Cathedral
  • Roughcast
  • Mistlite / Satinlite / Pacific
  • Cotswold / Seadrift
  • Narrow Reeded
  • Broad Reeded
  • Flemish

Some patterns can be toughened and or laminated for safety glass but some deep patterns cannot. Most can be used in IGUs but the pattern side may need to be on the outer surfaces (1 or 4).

 

Decorative

Decorative glass is often associated with special antique or coloured glasses used for lead lights and copper lights but can also be patterned. In addition decoration may be achieved by a range of processes;

  • Antique
  • Coloured
  • Stained
  • Acid etch
  • Sand blasted
  • V cut glass
  • Mirrored glass
  • Painted glass
  • Filmed

 

Mirror

Silver is used to create mirrored glass and it is protected by copper or passivation and special paints on the back.  Any glass thickness or tint can be mirrored but it is most common in clear 3, 4, 5 and 6mm. Safety “vinyl back” mirrors are also available for extra safety applications, and heated pads can be fitted.

Typical products are;

  • Clear silver mirror
  • Tinted mirror
  • Antique mirror
  • Safety back mirror
  • Heated mirror (mist free)
  • Venetian mirror (stripes)
  • Mirror tiles (plain or bevelled)
  • One way mirror (see applicable section as this is not mirror glass)

 

Back Painted

 

 Modern paints using adhesion additives have allowed a wide range of standard paint colours to be applied to glass. Typically they are called and used as “splashbacks” but have a wide range of uses, normally internal.

  • Splashbacks for Kitchens and Bathrooms
  • Bath and shower lining
  • Cupboard doors
  • Vanity tops
  • Bar and counter tops
  • Furniture
  • Wall cladding
  • Partitions and screens
  • Signage boards

In most cases they are toughened for safety and to comply with gas appliance standards and the paint is normally applied to low iron glass to achieve exact colour matching.

Size limits apply according to the manufacturer and care is required with the glazing and sealing methods.

 

Glass Blocks

Glass Blocks are manufactured by casting two shells and forming them to together to seal the airspace. They provide good thermal and sound insulation and in combination with colour and surface patterns they can create spectacular lighting effects.

Typical sizes are as follows

  • 190 x 190 x 80
  • 240 x 240 x 90
  • 146 x 146 x 80
  • 240 x 115 x 80
  • Special 45 degree corner blocks

Glass blocks can be fire rated up to 1 hour in a steel frame and glazed into special aluminium frames with grout and or silicone.

 

Security

Laminated glass can be made to resist severe purposeful or accidental impact and is often constructed from combinations of multiple layers of glass and thick interlayers.  

Typical types are

  • Anti- Bandit for smash and grab - typically 7.5 and 11.5mm
  • Intruder Resistant for higher security - typically 14 to 23 mm
  • Prison and Suicide cell for security and safety – typically 14 to 20 mm

Various combinations are available depending on the level of resistance or attack weapon and international standard performance. The frame design is critical in order to equally resist the force imposed.

 

Cyclone Resistant (CR)

 Laminated glass can be made to resist extreme wind and wind airborne flying debris that occurs in cyclone conditions. In such situations the glass must withstand penetration from a 4kg 100 x 50 mm timber plank travelling at 15m/s or more. To do this the interlayer must be strong and thick and typically 14mm (5/3.8/5) thick. Sometimes the glass is thicker as the wind pressures are very high in cyclone conditions.

 

Bullet Resistant (BR)

Bullet Resistant glass is multi laminated glass and in some cases uses layers of polycarbonate inside. It ranges from 20 to 75mm depending on the weapon such as

  • 9mm handgun
  • 357 magnum
  • 44 magnum
  • AK 47 and 5.56 rifle
  • 62 NATO rifle

 Various combinations are available depending on the level of resistance or attack weapon and international standard performance. The frame design is critical in order to equally resist the force imposed

 

One Way Vison

 One way vision is not a glass but rather an effect created with low light transmission reflective glass. Special glasses are used to create a lighting ratio of 8:1 or 10:1 between the observation and subject side. Therefore the subject side needs to be 10 times greater than the observation side.

 

Photovoltaic

BIPV or Building Integrated Photovoltaics, are a specialty glass element. They are available in either transparent or translucent glass with integrated solar cells to convert clean electric solar energy into electricity. This means that power for a building could be produced within the roof, canopy, skylite or from the glazed vertical façade elements. The glass types can come in laminated and high performance specifications including IGUs as required, offering thermal insulation properties as well varying transparency levels, providing a shading element and reduction in solar gain.

The solar cells are embedded between two glass panes and a special resin is filled between the panes, securely wrapping the solar cells on all sides. Each individual cell has two electrical connections, which are linked to other cells in the module, to form a system which generates a direct electrical current.    

There are a number of international projects around the world incorporating this technology setting a precedent for zero carbon power generation. 

Woods Glass are constantly reviewing offshore technologies and are seeing that the efficiencies and cost of this technology is becoming increasingly more feasible. We have technology agreements with many specialty glass suppliers and can assist your project's integration of BIPV products.  If you need assistance with a 'total' off-grid integrated glass solution - please contact us to discuss your needs.

 

Switchable

Switchable Glass is a laminated glass with a liquid crystal inter-layer that carries an electrical charge. When current runs through the glass inter-layer the crystals align which makes the glass transparent.  However when the power is turned off, the crystals randomly overlap causing an opaque privacy glass.  

Switchable glass is great for when a clear or tinted appearance glass pane is required, then with the flick of a switch the glass pane goes from transparent to opaque, offering privacy. 
Uses include projector screen walls, meeting rooms, bathroom divider walls etc.

Woods Glass has a relationship with the provider of this technology with a long history in the industry (since 1990) and one of the highest clarity systems in switchable privacy glass technology.

Sizes are limited to 3500 x 1820mm and glass can be clear or tinted annealed, heat strengthened or toughened safety glass. It can also be made into an IGU. In special cases it can be shaped curved and made with cut outs.

New technology allows blinds (lines) or logos to be switched on and off in the glass for special effects.

See more information see www.polytron-global.com 

 

Heated

Heated glass is a coated glass with an electrically conductive coating, in which the electrical resistance produces heat energy and warms the glass. The coating is protected inside laminated glass or an IGU.

 Heated glass is best suited for applications requiring passive condensation control and thermal performance and high visibility, such as commercial refrigeration, and marine window applications.   

 Large sizes can be made up to 5180 x 2500 mm and the glass is toughened due the operating temperature.

 

Self-Tinting

VariShield self-tinting glass is a unique thermochromic laminated safety glass with a special interlayer that tints darker when exposed to the sun (heated). It has no wires, electrodes, power supplies or controls and no tricks – just the sun.

 It allows approximately 50% of the visible light transmission (VLT) under normal cloudy conditions to transmit internally and as the sun beats down on the glass it darkens to around 10% so you don’t need blinds, drapes and shades and don’t need to worry about glare. It also reduces UV and sound so it provides a better working environment, and is best suited for east, north and west sunny faces of the building.

 VariShield is combined with low e glass and used in IGUs to provide brilliant performance and lower the shading coefficient (SC) down to as low as 0.14 with a U value of 1.3 W/m2K

 It is limited in size to 2700 x 1650mm

 

Electrochromic

 Electrochromic glass is very sophisticated and is often known as “Dynamic Glass”. It has a special coating with 5 layers of ceramic material so when you apply a low voltage the electricity darkens the glass by electron transfer. Reversing the voltage causes the ions and electrons to their original clear state.

 The result is a glass that absorbs and re-radiates away the suns unwanted heat and glare at the a flick of a switch so you can maximise daylight and solar energy.

 The coatings are only used in IGU combinations to provide optimum performance, and size limitation apply.  


 

Data Shielding

 Radio frequency (RF) can be a nuisance and electronic eavesdropping can be used to gain valuable and confidential data. Data shielding glass reduces the transmission of radio frequency (RF) as is sometimes known as RF shielding.

 The glass is often used in high security IT installations, television and radio stations, security and computer installations.  

 

X-Ray

 X-Ray glass is often known as “Radiation Shielding” glass, or “Lead Glass” as it contains lead to screen out X-Ray radiation used in CT scanning rooms and the like. The high barium and lead content make the glass very heavy and it is rated according to the lead equivalent required for protection.

 The minimum lead equivalent options are normally 1.1, 1.5, 1.8, 2, 2.2, 2.5 and 3mm and the glass ranges from 6mm to 12mm. The glass is limited in size and is very heavy due to the lead.    

 

Films & Coatings

 Glass can have a wide range of films and coatings applied after manufacture in addition to the special glass coatings applied during manufacture

 Typical Films and coatings  

  • Clear safety film
  • Clear security film
  • Solar tinted or reflective films
  • Low e film
  • Anti-graffiti film
  • Decorative films
  • Safety mirror film or coatings
  • UV elimination coatings
  • Easy clean coating
  • Low e coatings  

 Most have limited warranty and durability but in some situations they are suitable.

 

Do you have a technical question?

We've compiled an intuitive inquiry section which will help you get the knowledge you need.

 

Technical Inquiry >

Auckland Office
+64 (0)9 525 3379
Fax: +64 (0)9 525 8200
enquiry.akl@woodsglass.co.nz

Wellington Office and Factory
Phone: +64 (0)4 913 1999
Fax: +64 (0)4 939 4499
enquiry.wgtn@woodsglass.co.nz

Christchurch Office and Factory
Phone: +64 (0)3 366 3733
Fax: +64 (0)3 365 6422
enquiry.chch@woodsglass.co.nz

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