What Causes Fading of Fabrics, Interior Finishes, and Furnishings?
About 40% of all fading is caused by ultraviolet (UV) light, 25% by visible light, 25% by heat, and 10% by humidity, chemical vapours, age of material, dye stability, etc. Since UV light rays bounce off solid objects; buildings, trees, pavement, etc., regardless of which direction your windows face, you may have a fading problem. Natural fibres like silk and wool are less fade-resistant than synthetic fibres. Antiques, tapestries, rugs, etc. have relatively unstable dyes, and will fade quickly. Fluorescent dyes are less colour-stable than non-fluorescent dyes.
How Can I Reduce Fading?
Reduce the Amount of UV Light.
Special absorbers in SuperTint films block up to 99% of the UV-C (light with a wavelength of between 320 and 380 nano-metres — nm). UV-B (between 280 and 320 nm) is blocked by glass. UV-A (below 280) nm is blocked by the Earth's ozone layer. Modern fluorescent tubes have special glass that eliminates almost all UV light. Most older bulbs, however, still transmit most of the UV. Applying a clear SuperTint film (such as UVCL-SR-PS1) to the lens cover will dramatically reduce UV levels.
Reduce the Amount of Heat
Ordinary clear window glass blocks some of the solar heat:
- single-glazed windows with 1/8-inch glass will stop 13%
- single-glazed windows with 1/4-inch glass will stop 17%
- double-glazed windows with 1/8-inch glass will stop 23%
- double-glazed windows with 1/4-inch glass will stop 29%
- virtually any type of SuperTint tint on a window will reduce the amount of heat getting through it.
A single 150 Watt incandescent spotlight produces over 500 BTUs per hour. A 75 Watt display spotlight in an elliptical reflector produces the same amount of light but just half the BTUs, and does it at half the energy cost. By choosing light bulbs carefully, you can reduce internally generated heat in your home or office. Source: "Window Film Training Guide" published by the Association of Industrial Metallizers Coaters and Laminators (AIMCAL). The complete Guide is available from SuperTint.
What Does Film Look Like?
The photo below shows the effect of installing SuperTint N-1035 Bronze film on clear-glass, south-facing, double-glazed windows. Notice the bright sunshine on the floor in the left-hand picture, compared to the muted sunshine through the same pane of glass in the right-hand photo. To people, the biggest differences are the reduction in heat and glare. But your furnishings will notice the 99% decrease in UV light too.
Fade Protection Charts
Here are detailed charts showing the amount of fade reduction that can be achieved with various SuperTint window films. If you don't like charts, here's the conclusions that we reached, based on our calculations. Regardless of which film you choose, you will get some reduction in fading because:
- all SuperTint films eliminate over 95% of the fading due to UV light
- tinted SuperTint films also reduce fading due to solar heat
- reflective SuperTint films offer maximum protection from fading caused by both UV and solar heat.
Scratch-Resistant Coatings on SuperTint Films
All SuperTint films are protected by a scratch-resistant (SR) coating on the exposed surface. This micro-thin layer of proprietary acrylic, cured with ultraviolet (UV) light, was among the first such coatings developed for the solar-control film industry. Testing by Courtaulds Performance Films (now known as CPFilms Inc.) in the 1990s indicated it was the hardest SR coating on the market.
How Are SR Coatings Tested?
There are two ways of testing SR coatings:
- Fine (0000 grade) steel woolis used as a quick way of determining scratch resistance. The SR coating on SuperTint films can be vigorously wiped with 0000 steel wool without leaving any noticeable marks.
- A more quantitative test is the American Standards and Testing Methods (ASTM) Standard D 1044. It uses a tool called a Tabor Abrader, which can be loaded with a variety of weights and abrasion wheels. The unwritten industry standard is to use a 500 gram weight and a fairly soft CS 10F wheel. Tests done by DSET Laboratories in Phoenix, AZ, in 1997 showed an average of 0.02% reduction in light transmission through a number of samples of SuperTint R-20 film after 100 cycles of abrasion. More rigorous testing was done by Courtaulds Performance Films, using a 1000 gram weight and a harder CS 10 wheel, as it was not felt the standard test gave the measurement definition required. Again, only slight variability in light transmission and haze was observed.
So what does all this mean to you as a consumer?
Simple; you can be confident that your SuperTint film installation will stand up to normal, day-to-day wear and tear without damage, for many years.
How to Turn an Interior Window Into a One-Way Mirror
Did you know that an ordinary piece of glass can be turned into a one-way mirror if it's treated in the proper way and certain conditions are met? This is how it's done: First, apply a piece of highly reflective film, such as SuperTint R15G, to the 'public' side of the glass. (That is, to the side on which the people being observed are sitting or standing; the observer is on the 'private' side of the glass.) This is the easy part. Second, ensure the light levels on the private side are kept lower than those on the public side of the window. This is the difficult part, and if it's not done properly, the effect of the reflective film will be severely diminished and people may be able to see through the 'mirror'.
What can be done if the light levels of the two adjoining spaces must be kept at the same level?
There are several solutions. The most practical one is to increase the light level in the public space immediately next to the one-way window. This can be done with small spotlights focused on or near the window, or a slight increase in overall light intensity next to the window. On the private side of the window, you could install Venetian blinds and keep them partially closed. This should allow reasonable visibility through the window, while still reducing the amount of light hitting the glass.
Where are One-Way-Mirror Windows Used?
One-way-mirrors are commonly used in areas where unobtrusive surveillance is required. Although many people will immediately think of being spied on by their bosses, they're more likely to be observed in a mall or a casino, where the security staff is looking out for thieves and troublemakers.
Are One-Way-Mirror Windows Legal?
Yes, unless they are used in areas which people would reasonably expect to be private, such as a changing room in a clothing store or a washroom.
Plants and Window Films
Are you hesitant about putting reflective film on your windows for fear your plants will die? Don't be, putting an appropriate film on your windows will not adversely affect your house plants.
- Fact: According to landscape horticulturist Dr. Robert E. Moon of Texas A&M University, plants do not need ultraviolet (UV) light for proper growth. They use the far red and blue portions of the visible-light spectrum for growth. SuperTint reflective films reduce the intensity of this light, but do not totally block it, so your plants will still be happy.
- Fact: Most tropical plants require less light and heat than they often receive in a typical North American home. Properly installed SuperTint film allows sufficient light for good plant growth, while reflecting excess heat that can cause rapid drying of soil and even burning of leaf ends.
- Fact: Plants with light green or variegated leaves (leaves having two or more shades of green) require more light than plants with dark green leaves.
Having said all that, it's still necessary to ensure the proper film is selected for a room containing plants.
For example, if your concerns about overheating are equally balanced by concerns about the health of your plants, select a medium-reflective film, rather than a highly reflective film. R-35 film allows 25% of the visible light striking the window to pass through, while SuperTint R-20 film reduces that to 13%. Obviously SuperTint R-35 will allow better plant growth than R-20, while still doing a good job of controlling excess light and heat. Rooms with serious overheating problems are probably not good places for plants anyway, so consider moving them to a cooler place and installing a highly reflective film to control overheating.
If a heavy film (such as R-20) is installed, plants in that area may go into a slow-growth mode for some time as they adjust to the lower levels of light and heat. If this continues for a long time, or if the leaves start to wilt or lose colour, you should move the plant to an area with more light, or install a plant light.
Are there any SuperTint films which are not recommended for areas with plants? Yes, according to CPFilm and SuperTint R-15B, R-15-G, and R-15GO will definitely inhibit plant growth. SuperTint R-30B and R-30G will reduce plant growth, but will not harm plants.
A Study of Seal Failure in Windows with Film Applied
It has long been claimed by many window manufacturers that applying window film to sealed units is detrimental to the window. For this reason, most manufacturers will void their seal-failure warranty if any film is applied to the unit. A recent study by an independent engineering firm has shown that this assertion is essentially unfounded.
Sealed units are made of two or more lites of glass separated by a spacer which contains a desiccant to absorb moisture from the air (see drawing right). One or two seals (primary, or primary and secondary) seal the glass to the spacer and keep moisture out of the space between the lites. If the seal fails, the desiccant will be saturated and condensation will appear between the lites, fogging the window.
Premature failure of a sealed unit can generally be traced to one of three causes:
- poor design of the unit itself
- poor workmanship during manufacturing
- poor frame design which allows the unit to sit in a high-moisture environment
As a result of studies done by the Sealed Insulated Glass Manufacturers Association (SIGMA) since 1980, window manufacturers determined that if these three problems were eliminated, a sealed unit built to SIGMA standards had about a 1% chance of failing before its warranty period ended. (Of course, not all windows are built to SIGMA standards, and failure rates for these units may be higher.) As noted above, however, many window makers feel the application of film to their units increases the chances of seal failure.
Written requests by the Window Film Committee of the Association of Industrial Metallizers, Coaters, and Laminators (AIMCAL) for test results substantiating these concerns found that no such test data existed. So AIMCAL asked Lingnell Consulting Services, the technical consultant to SIGMA, to test standard sealed units, with and without film, following ASTM test methods E773 (accelerated weathering) and E774 (fogging).
Both commercial (double-sealed) and residential (single-sealed) units were tested. With the exception of one residentialunit that failed to pass the third (toughest) level of testing due to a manufacturing defect, Lingnell's conclusion was that "there were no substantial differences between the insulating glass units with the film and without the film for the tests run on these samples.
In other words, applying an appropriate film to a sealed unit built to SIGMA standards will not adversely affect its seal. This is good news for anyone selling or using film; we finally have independent, authoritative proof that window film, when applied according to manufacturer's specifications on quality sealed units, will not cause the window seal to fail.
Metallizing vs Sputtering
Virtually all residential and commercial window films contain an incredibly thin layer of metal between two layers of plastic. The type of metal used and the way in which it is deposited determines the film's reflective characteristics. There are two common ways of producing this very special layer of metal; metallizing and sputtering. Some film manufacturers have been known to claim one process (the one they use) is superior to the other (the one their competition uses). Here's our opinion.
What is Metallizing?
Metallizing is the process by which a pure metal (such as aluminum, stainless steel, or copper) is heated in a vacuum chamber until it vapourizes, and is deposited in a micro-thin layer on a substrate; in the case of window film, this is polyester. It is possible to have minor irregularities appear in metallized film.
How Big Would An Irregularity In the Coating Have To Be Before It Could Be Seen?
Over 100 nanometres high, which is something like 10 times the average thickness of the coating. Although it is theoretically possible for this to occur, metallization technology is well enough understood that the chances of this occurring without being detected are negligible. Think how difficult it would be to not notice that your cat (dog, kid, spouse — take your choice) is hiding under the living-room carpet.
What is Sputtering?
Sputtering is the process by which a metal alloy is subjected to an intense electromagnetic field and bombarded with ions, to the point that individual atoms are dislodged from the surface of the alloy, and scattered uniformly across the substrate.
How Are These Coatings Protected?
All sputtered and metallized films are laminated with a second layer of polyester, with the coating in the middle, so the metal is protected. The second layer of film may be dyed, yielding films with an even wider range of colours and performance characteristics.
What are the Advantages of Metallization Over Sputtering?
It is a less complicated, and thus less expensive process. Metallization produces a more columnar coating than sputtering, which allows the film to dry much more quickly. The installation process is also not quite as finicky, because the film is more forgiving. Metallizing is an ideal process for manufacturing silver reflective film.
What are the Advantages of Sputtering Over Metallization?
A much wider range of colours, heat-rejection characteristics, and appearances can be achieved since there are more alloys that can be used than there are pure metals. The molecular structure of a sputtered coating is thinner and tighter than a metallized coating, which means the final product can be less reflective, yet reject a significant amount of heat. Sputtering is best suited to lower-reflectivity bronze and neutral grey films, as well as high-performance films.
Which Process Is Better?
Neither. Both produce very specific types of coatings intended to achieve certain effects. The type of effect wanted determines which process is used. Neither process will yield films that will always out-perform films made using the other process; there are films from each process that run the full performance spectrum. CPFilms (the manufacturer of SuperTint films) is the only window-film manufacturer that does both sputtering and metallization in-house, which allows them to choose the best process for each particular film. Like CPFilms, virtually all film manufacturers choose to metallize reflective films, and sputter non-reflective films.
UV Absorbers in SuperTint Films
As discussed in "FAQ's on Fading", fading is caused primarily by light and heat, as well as by humidity and other minor factors. The only way to totally eliminate fading is to place the item to be protected in a cool, dry, totally dark environment. Using window film is an ideal way of reducing fading of anything you don't want to put in a dark room in a dry basement.
Window films reduce fading by absorbing the ultra-violet (UV) energy in the sun's light. Some film manufacturers put UV absorbers only in the film adhesive, not in the film itself. CPFilms puts UV absorbers in both the adhesive and the film. This means that as the effectiveness of the UV absorbers diminishes over time, the combined effect of two sets of absorbers continues to protect your valuables.
New SuperTint films reject 99% of the UV-C (between 280nm and 380nm) light striking the film. After 2000 hours of accelerated testing in a zenon chamber (equivalent to three to five years of normal exposure, depending on location), the film continues to reject 98% of the UV. Films with absorbers only in the adhesive absorb between 96% and 98% of UV when new, and as little as 93% after testing.
Most people have heard of low-e windows, but what are they, what makes them special, and why should you care if you have them in your house? Low-emissivity (low-e) glass looks just like ordinary glass, but it behaves quite differently. During the manufacturing process, the glass goes through a vacuum chamber where a microscopically thin layer of tin oxide or silver is deposited on one side. The glass is then heated to bake the coating onto it. This invisible layer reduces the surface emissivity of glass, meaning it reduces the amount of long-wave infrared thermal (heat) radiation both absorbed and emitted by the glass.
When low-e glass is used in a double-glazed unit, the coating is generally on the outer face of the inner pane of glass (for the technically inclined, that's called 'surface three'). This way, heat loss is greatly reduced with almost all re-emission taking place towards the interior of the building in cold climates (if the coating is on surface three) or back out into the environment in a hot climate (if the coating is on surface two).
In a cold climate, low-e glass will save you some money on your heating bills, but more importantly, it makes the area close to your windows more comfortable in cold weather. Since you don't feel as much chill off the windows, there's less temptation to crank up the thermostat, which really will affect your heating bills! So, if you have regular glass in your windows, can you do anything to them to achieve the same effect? Yes – have low-e window film installed on them.
Low-e film goes on the inside of the window, with the low-e coating close to the glass. As with most films, the inner surface of low-e film has a scratch-resistant coating, although it has to be slightly thinner for the low-e effect to work properly. Low-e film, however, works in the same manner as low-e glass – the window rejects excess solar heat in the summer and reflects heat back inside in the winter, making it more comfortable year-round.
Heat Gain in Summer vs. Winter
The amount of heat that is gained through windows during the winter is quite different from the amount of heat gained through those same windows in the summer.
How Can That Be?
The reason for this is very simple; orientation. East- and west-facing windows receive fewer hours of intense sunshine during the winter than they do during the summer. This is due to the seasonal movement of the sun – it rises further to the southeast, is lower in the sky during the day, and sets further to the southwest in the winter than in the summer.
So the sunlight striking east-facing windows first thing in the morning in December is coming from a very low angle, from well to the south of due east. And in the late afternoon, the sun is setting in the southwest before it can really heat up west-facing windows. During the day, when the sun is low in the southern sky, most of its energy goes straight through south-facing windows.
During the summer, however, the reverse is true. The sun rises very early, in the east or northeast and starts pumping a lot of heat through east-facing windows well before most of us are awake, and in the evening, it's still shining through west-facing windows when some of us are going to bed. During the day, of course, it's high in the southern sky and much of its energy is reflected off of south-facing windows.
The net result is that a building with a lot of east- or west-facing glass will heat up earlier and stay hot longer during the summer than a similar-sized building with little or no east- or west-facing glass. The real problem arises when the building design or other considerations demand a lot of east- or west-facing glass, and the occupants feel like they're living in a sauna every summer.
What Can Be Done About It?
Reflective window film will dramatically reduce the amount of heat passing through a window. The more reflective the film, the greater the heat reduction.
Depending on the building design, window orientation, and other site-specific conditions, it might be advantageous to put a more reflective film on the east- and west-facing windows than on the south-facing windows. This will allow more heat gain through the south windows year-round than would be the case with a more reflective film. If the extra heat is desirable during the winter, and the C south face of the building can be shaded during the summer, this may be a good solution. If there are a lot of south windows and they cannot be shaded, however, summer-time overheating may be a problem.
The proper choice of window film (or films) for a building – home, office, or commercial – can be a complex problem, with consideration being taken of the type of building, number and orientation of windows, and need for heat gain or rejection at various times of year. To be sure you get the best answers for your specific location, talk to an expert – SuperTint