Frequently Asked Questions
- How does one way / two way film work?
- Why does one way window film not work at night?
- Why is the mirror film you installed on my windows not working?
- Will Window Film cause my glass to break?
- How long will my Window Film last?
- What are the regulations regarding Manifestation?
- What causes toughened glass to suddenly shatter for no apparent reason?
- What are the legal requirements for maximum workplace temperatures?
- Will Window Film take away a lot of natural light?
Picture the scene - In any TV crime drama where an identity parade is taking place the “line-up” always stands in a brightly lit area while the viewers are always in a darkened room observing through "one way" glass.
"I want to see out, but want to prevent able to see in" is a common remark heard almost on a daily basis by anyone involved in the business of supplying or installing window film. The reality however is quite different than simply applying a layer of reflective window film to a pane of glass to achieve "one way vision". The secret lies not in the film or the glass but in the prevailing lighting conditions.
Buildings with "mirrored" windows are now a common sight in most of our towns and cities. This is usually glass treated at point of manufacture with a reflective coating or windows that have been retrospectively coated with a reflective solar control window film. The reason why these windows appear mirrored from the outside yet can be viewed through from the inside is due to their metallised coating and the differential in external and internal light levels.
The installation of reflective window film or glass within the external facade of a building does indeed afford privacy to the occupants but only during daylight hours. During the hours of darkness with internal lighting in operation the windows become "see through" from the outside.
Because external facing windows often only require "one way" vision during daylight hours such as offices, night time transparency is not usually an issue.
When the requirement for "one way vision" concerns internal glazing such as office partitions or vision panels the effect is much more difficult to achieve and in many cases nigh on impossible. Unlike external glazing, internal windows usually have similar amounts of light present on both sides of the glass. Should the light differential between the "private" side and the "viewing" side be less than a ratio of 1:7 this will probably result in total transparency or total obscurity from both sides no matter which way round the film is installed onto the glass.
To overcome this issue in an office environment where you have a window dividing two internal spaces, additional lighting can be introduced to one side of the glass or alternatively the amount of light on one side can be greatly reduced to produce the “one way vision” effect.
There is absolutely no exception to this rule. One way / two way vision glass or film does not work by magic but simply by the laws of science.
No, the application of Window film alone will not cause glass to break!
However we do understand that any application of Window film can cause an increase in temperature within the glazing system and will increase the stress on the glass edges. The quality of the glass edges and several other factors (internal and external shading, glass history, type of film, type of glass, size and shape of glass) all contribute to the potential risk of glass breakage.
Peace of Mind with Lustalux
Lustalux’s twenty five years of experience in the specifying and installation of Window film in many differing situations and locations enables us to make properly informed film to glass recommendations.
With the backup of our leading manufacturers, we undertake thorough surveys and film to glass compatibility checks prior to any installation to minimise any potential risk of glazing failure. After these checks are completed and approval is granted, your glazing is warranted for any failure directly attributable to the applied film.
Lustalux only uses the highest grades of film from reputable manufacturers. Because of this and because we stand by the quality of our installations most of our window films are now warrantied for at least ten years with a total life expectancy in excess of fifteen years.
In recent years externally applied window films have become more readily available. Naturally these films have to withstand more potential degradation due to climatic conditions however many of them are now available with seven to ten year warranties. All our externally applied films are edge sealed with a high grade silicone sealant for added protection.
Generally speaking to comply with DDA regulations manifestation in it's most basic form consists of two rows of markings in a material contrasting with the background of any full height pane of glass. One row should be at around 850mm and one row at around 1500mm from finished floor level. For a more detailed and in depth explanation of the regulations please visit our manifestation page.
The main cause of the spontaneous breakage of glass is something called Nickel Sulphide Inclusion. Put in simple terms these are impurities present in toughened glass originating from the manufacturing process. Over time these "contaminants" are placed under stress causing the glass to shatter. For a more in depth explanation of spontaneous breakage please see here.
To remedy this potential safety hazard Lustalux can provide a glazing containment system. There is a case study of such an issue here.
Maximum permitted temperatures in the workplace depend on what activity is take place in a given place of work. For example manual work will require lower temperatures than an office. The HSE (Health and Safety Executive) web site provides some definitive guidance here. The Business Advisory Service advises " Apply sun-control or other reflective films on south-facing windows to reduce solar heat gain"
It is generally accepted that thermal comfort for most people in the UK lies roughly between 13°C (56°F) and 30°C (86°F), with acceptable temperatures for physical work activities erring towards the lower range, and for less physical activities towards the higher end.
It depends on which issues you need to address. If for example you have a severe glare issue to resolve, it would be pointless installing a light or virtually clear film. After all you wouldn't buy a pair of sunglasses with clear glass in would you? With over twenty years of dealing with solar related issues we at Lustalux are confident that we can match a product with your glass to provide a satisfactory outcome.
If you have overheating issues through your windows we can provide a solar control window film to deal with the problem with the minimum of impact on light levels. If however you also have a glare problem we will endeavor to strike the right balance between light loss and effectiveness. In most cases a small trade off in light loss is more than compensated for in improved comfort levels.