TIP#11 - How to control Haze phenomena in Privacy Glass

When you chose Privacy Glass you always compromise on full transparency of the glass. Haze, is the kind of fog, which looks like cloudiness, is a result of the light scattering of the Liquid Crystal (LC). NCAP PDLC technology minimize the Haze and is considered to be the best technology for producing NCAP PDLC. Technological advantages including unique production methods that keep the spherical structure of the LC molecules and minimize light scattering when the glass is transparent (On state).

Haze level can be minimized or emphasized based on the below factors:

Viewing Angle: Haze is minimized to almost not exist when you view the Privacy Glass in 90° and will be emphasized when viewed in 30°. Therefore, you wish to position the Privacy Glass in 90° if application allows it.

Light: Haze is minimized when you have equal light from both sides of the Privacy Glass and will be emphasized when you have stronger light from one side. Light is scattered so you wish to balance the light from both sides. Fluorescent light may reflect flickering effect on the Privacy Glass so you may want to avoid it. Direct Sunlight will emphasize the Haze so it is also not recommended.

Glass Type: Haze is minimized when you chose a tinted glass and emphasized when you go with low iron glass. It is simply because the glass tint absorbs some of the light and therefore it minimizes the light scattering resulted in minimizing the Haze.

TIP#10 - Is the privacy glass allows better acoustic insulation?

Absolutely! Privacy Glass is made of many layers; therefore, it provides excellent acoustic isolation. The Privacy Film itself is made of 3 layers, there are two PET/ITO substrates and the Emulsion in between. This 3-layer structure is laminated with two glasses and 2-4 EVA inter-layers so altogether you are looking at a complete structure of 7 to 9 layers. In terms of the level of insulation, the numbers speak for themselves.

Double Glazing
Double glazing window, especially when acoustic glass is used, helps to insulate against the nuisance caused by outside noise. Laminated acoustic double glazing window can reduce noise levels by up to 35 decibels.
Privacy glass has several layers hence contributes to better acoustic.

The actual level or intensity of noise is measured in decibels (dB). The scale is logarithmic, so 50 dB + 50 dB is not 100 dB, but 53 dB. Thus, halving or doubling the effect of the sound corresponds to 3 dB. The human ear recognizes sound as halved or doubled each time the level is changed by approximately 8-10 dB. (source Alpha Akustik). 

Improving acoustic insulation
Acoustic glass works by reducing a sound wave’s energy. The acoustic insulation properties of a window are measured with the ‘R’ sound reduction index. For example, a window with an R of 20 decibels should reduce a 60 dB outside traffic noise level to 40 dB within the room.

Improving the sound insulation of a double glazing window can be achieved by:
- Having the widest possible cavity between panes of glass
- Using thicker glass
- Differing the thicknesses of the two glass panes used
- Using an efficient insulating window frame
- Using specially laminated acoustic glass
Acoustic glass is a sandwich of two or more sheets of glass, heat or pressure bonded together with one or more acoustic EVA inter-layers. The inter-layers act as a noise damper, weakening the energy of the sound waves as they travel through the glass.

Privacy glass is a perfect solution for insuring exceptional levels of sound insulation. It not only provides insulation for impact and airborne noise but also maintains the safety and security properties of laminated glass.

Privacy glass can be functional to both commercial and domestic buildings when applied to products such as windows, patio doors, skylights, conservatories and internal screens and partitions.

Below is a table representing the noise isolation values for the different glass thickness and lamination configuration:

Glass Structure

dB Acoustic Rating (Rw)

4+4 mm glass

36

5+5 mm glass

37

6+6 mm glass

38

Triple laminate IGU

47

 

TIP#9 - What are the advantages of extra clear film?

SFI is the developer and manufacturer of its proprietary based Liquid Crystal Films.
The technology is based on 25 years of research that has produced industry-leading IP.

This technology is referred in the market as NCAP PDLC abd the products is called ExClear Smart Film. ("ExClear Film").

SFI’s ExClear Films for privacy glass applications is electrically operated. In an 'OFF' mode the LC is opaque and in “ON” mode, when voltage is applied, it becomes transparent.

With NCAP PDLC process, self-encapsulating LC micro-droplets are coated on thin and flexible substrates to form durable, reliable, and robust LCs that can be
produced in a wide variety of shapes, sizes and shades. Glass laminators are using a high-yield, high throughput, roll-to-roll (R2R) process. Our LC provide designers with easy inexpensive
choices for creating products with a wide variety of form factors, including surface curvatures.

Our ExClear Films are shipped in large quantities and have been integrated by our customers into finished products across a myriad of markets: architectural (privacy) glass, home
appliances, signage, flexible displays and more.

Features of ExClear Film include:

  • Most transparent smart film
  • Customized EVA for better lamination results
  • Extremely low power consumption: 5 W/m2
  • Can be laminated onto a wide variety of glass or plastic materials
  • Can be laminated onto curved surfaces
  • Low haze (6%) and good clarity (92% light transmission)
  • Angel: 180 degrees
  • High-yield, low defect density
  • Additional UV protection is not required
  • Long-lasting: 20+ years indoors

TIP#8 - Who can install privacy adhesive film or privacy glass?

Installing of Privacy Adhesive Film or Privacy Glass demands expertise.

Privacy Glass:

Installing of Privacy Glass is basically similar to an installation of any other glass. You need to be able to lift the glass to the installation area with no damage, use proper frames and put the glass in it.

A privacy glass may have different properties:

  • Tempered (Toughen) or not tempered.
  • Different thickness 4+4, 5+5, 6+6, 5+7mm
  • Clear (usually come green) or Super clear color (no yellowish or greenish print)
  • It has wires come out from one or two edges. These wires should be connected to a special transformer.
  • With cuts and holes or not
  • Framed with a special Silicone protection to avoid humidity exposure

The installer has to pay attention the following matters:

  • Use of a special no ACID Neutral Silicone
  • With the help of a qualified electrician
  • to connect the wires to transformer
  • to add a remote control if needed

Click here to view pictures.

Privacy Adhesive Film

Sticking of adhesive film over an existing glass need experience and expertise. Although it may be easy with small size film, it happens to be more challenging with bigger size.

PDLC adhesive film is even more challenging as there is no room for mistakes...The film already comes with electrodes and wires on it so there is one “shot” to stick it.
Unlike 3M film or any other “milky” visual film that stick to the glass with water, the PDLC adhesive film is a dry stick, the challenge is make is fast, right and with no bubbles.

The installer has to pay attention the following matters:

  • Before installation, read carefully our Installation Guide.
  • Clean very well the glass. 2/3 of installation time should go to cleaning the glass.
  • Use of a special no ACID Neutral Silicone
  • With the help of a qualified electrician
  • To connect the wires to transformer
  • To add a remote control if needed

Click here to view installation clips.

TIP#7 – Smart film lamination: EVA or PVB?

EVA (Ethylene Vinyl Acetate) film and PVB (Polyvinyl Butyral) film are two different polymer materials that can be used for glass laminated structures. The PVB has been the reference material for the glass lamination on building construction and transportation industries for many years. EVA is challenging PVB as a lamination material because of its superior properties.

When it comes to laminated of PDLC film, meaning Liquid Crystal based smart film, then PVB interlayer is not suggested as PVB is damaging the PDLC film. The PVB "attacks" the PDLC film, doesn't matter the process you use to melt it: press or vacuum.

In light of the above, EVA is the interlayer of choice for us. There are many EVA types, each melt in a different temperature and it is very important to verify that your EVA melting temperature is same as your smart film melting temperature. Our EVA is customized for smart film lamination purpose.

What if I need to make a PVB lamination?

Lamination of smart film with PVB involved both pressure and heating.

You have to seal well all 4 sides of the smart film before the lamination (see picture). This adds much complexity to the process. This is why most of the customers are using EVA.

TIP#6 - When privacy glass comes as IGU?

IGU stands for Insulated Glass Unit.

It is more commonly known as double glazing or triplex. It consists of two or three glass window panes separated by a vacuum or gas filled space to reduce heat transfer across a part of the building envelope.
IGU is appropriate for building façade, sun roof, train windows and more.

To get Privacy, the IGU consist of:

Glass – LC – Glass – Air Gap – Glass (see picture).

Usually, we use Privacy Glass IGU in exterior locations when there is an exposure to sun.

One of the example is SINGAPORE LIGHT RAIL TRANSIT (LRT) Train Window. The train windows are IGU: PDLC Laminated Glass + Air + Glass. We provided privacy to the residential areas by automatic windows shut off whenever the train cross through the residential areas.

TIP#5 - How to choose privacy glass brand?

RELIABILITY 

This is the main factor. You need to get proof that the brand film is reliable over a long time (20 years). As the product is chemical based, the smart film is dynamic and in constant change which may be show defects over time on the Smart Glass (black spots and non-functional areas).

RAW MATERIAL QUALITY
We use high class LC and PET ITO raw material. It is more expensive than others in the market but it provides the highest level of both optical and instability over time.

TECHNOLOGY
There are in principle two ways to produce the Smart Film: (1) Micro Emulsion (NCAP PDLC) and (2) Phase separation. The Micro emulsion is much more complicated but provides a much better product since it keeps the spherical molecular structure. Transparency and Haze are much better than when produced in Phase separation as well as long time stability since it is water based, so it is very friendly.

Daily SHUT OFF
You do not want a film that cannot work constantly. If you are required to let the film “OFF” few hours a day, it means the film is not stable.

ADDED VALUE
You need to a company that will provide you with an added value based on cumulative experience. How to translate the product design for production, verify that the customer request is aligned with the product capabilities and limitations, exterior use vs. interior use, humid/wet environment etc. It is important to match the appropriate smart film and the lamination and sealing methods to the application.

EXPERIENCE
You want a company that has successful track record in production and installation as the product requires a very accurate process in production as well as installation. For example, sealing with a non-qualified Silicone will damage the product.

TIP#4 - Adhesive privacy film or laminated glass?

Adhesive privacy film is applied over an existing glass when a laminated film is laminated between two glasses and then the glass installed as a new glass.

Adhesive privacy film is ~10% less transparent then laminated glass due to the adhesive side of the PET ITO that add more “cloudy” layer to the film. There are Laminated film with 80% or 90% transparency and Adhesive film is around 70+% transparency.

Both film has same PDLC technology, same LC and need same electrical power to activate it.

Adhesive film has less warranty years as it is more exposed to humidity and heat then a film that is laminated and sealed inside a glass.

When it comes to a privacy film project, if the glass is there, Adhesive film is a less expensive and probably the right solution.
If design is still in process and still no glass, we recommend to have a Smart Glass rather than a film to stick on a glass.

 

TIP#3 - Interior or exterior (façade)?

We are often asked about whether Privacy Glass is suitable for Indoor and Outdoor. Here, we would like to discuss and clarify about it.

Bottom line, Privacy Glass provides privacy functionality and originally uses for interior applications such as partitions between bathroom and bedroom, meeting rooms, hospital applications, partitions in limousine and luxury cars and more. Such Privacy Glass is usually produced in a “sandwich” of 2-glasses lamination using inter-layer typically EVA or PVB. This is the best solution in terms of the performance and reliability of the Privacy Glass over time (>20-years).

For Interior use, when customer already has glasses in place, a Self-Adhesive Privacy Film is used. It is also called Retrofit and it is applied on existing glasses. As for Privacy Glass for Exterior applications, the standard configuration of 2 glasses lamination is good but no perfect, and we recommend a complete Insulated Glass Unit (IGU) where we produce Privacy Glass lamination as described above and laminate it to another glass with air gap/gas in between. The IGU will isolate the heat and cold and will keep your house from the exterior climate. In addition, we also recommend to have the said additional glass in the IGU tinted in a certain level in accordance with the direct sun light it is exposed to so you can choose the visible light transmission. The Privacy Glass IGU will provide a perfect combination of climate control and privacy on demand.

As for existing standard IGU that would like to apply privacy functionality (Retrofit), the Self-Adhesive Privacy Film will do the job. When you have a regular glass and you wish to turn it to climate control as well as privacy we offer the Self Adhesive Solar Control Privacy film.

TIP#2 - What is a fair price for privacy glass?

Pricing of Smart Glass is always a major subject, for the human eye it all looks the same but pricing significantly vary. in principle, there are many re-sellers but only a dozen of smart film producers worldwide. Each producer set the level of quality of raw materials. The major elements (over 90% of product cost) are the Liquid Crystal (LC) which responsible for the optical phenomenon and the PET/ITO which used as a substrate as well as the electrical conductor to the LC. When using top quality Japanese LC and PET/ITO a producer will pay 3 times and more compared with Chinese low quality materials. Labor and overall costs are relatively neglected as it required 2-3 people for production and relatively small space.

If you want to know how it will affect the product, in one word it is reliability over time. Since low quality raw materials are not stable, the Smart Glass may change its color, delaminate, bubbles will appear, non-functional due to shortcuts etc.

Replacing Smart Glass is very costly due to time, delivery and installation costs, not to mention the frustration. In most of the time it is very difficult to analyze the root cause of the problem, when the smart film is already packaged in the glass, so warranty may not be applied.

Our recommendations when choosing a Privacy Glass, are:

  • Make sure you are working directly with the producers. Today they are all working directly with customers.
  • Make sure that the producer has over 10 years of installations.
  • If price is less than $1,000 per square meter, you should be concerned.
  • Get a Sample/Demo before you place a commercial order