The Basics of Window Film Types

Some people tell me things like, "I just need tint" or "I need to block the sun." Please understand I need a bit more information in order to help you. I need to know the specifics of your goals and your windows. There will be questions I need to ask to understand all scenarios to recommend the correct product type. Below is a basic explanation of the different types of window films, and I will narrow down the selection based on the information you convey to me. All solar films reject >99% UV. Glare reduction and daytime privacy are determined by darkness, or visible light transmission. Nighttime privacy cannot be achieved with tinting of any kind due to the direction of light. Only a frost or decorative film of some kind will provide privacy at nighttime. These are not specific to any brand of window film. 

These are the oldest types of window films. They're still fairly popular in commercial applications, but not so much in residential due to color and interior and exterior reflectivity. Their solar performance is excellent and have low solar absorption. Silver films have a bluish-gray tone and usually come in shades of 20%, 35%, and 50% visible light transmission. Bronze films have a bronze color and usually come in 20% and 35%. Bronze films used to come in 50% but most manufacturers have discontinued that level. These films cost the least and give a lot of bang-for-your-buck if thousands of square feet are needed.

Dual-reflective films have become the most popular for both residential and commercial applications. They're used when high solar heat rejection is needed as well as glare control. The interior side has very low reflectivity and the exterior side gains reflectivity with darker shades. There are two types of dual-reflective films: Fully metalized and metal/dye hybrid. The fully metalized version will have a bluish-gray tone while the hybrid has an earth tone. It's a matter of color preference and which one looks better against the window frames and decor. These films are still lower on the price spectrum and range from 5% to around 40% visible light transmission.

These films are extremely popular in residential applications for their neutral and colorless appearance. When solar heat gain or glare aren't too bad but your main concern is protecting furnishings from fading, neutral films are a good fit. If you have a lot of white walls, trim, and decor, neutral films are nice because they won't cast a different hue causing a change of color of daylight. Visible light transmissions range from extremely light (about 65%) down to medium shades (about 35%). There are darker versions out there but their solar absorption levels are high and should only be used if the window composition allows them. Neutral films are in the same general price range as dual-reflectives.

When high solar heat rejection is needed without sacrificing more visible light than necessary, spectrally-selective films are a good choice. These films got their name because the ratio of visible light transmission to solar heat rejection (luminous efficacy) is over 1. Most of these films are non-reflective and extremely light (60%-80% visible light transmission) with solar rejection numbers around 50%-65%. There are medium shades that are reflective and are huge performers in knocking down solar heat gain. Because these films concentrate on infrared (or IR) rejection, please don't fall for IR rejection numbers. These numbers only specify particular IR wavelengths and do not measure the entire IR spectrum like the 99% number for UV rejection. This is a sales tactic and is deceiving. When choosing a spectrally-selective film product, look for an IR reflector and not an IR absorber. Look at the specification called Solar Absorption. This number is explained below and should be lower than the low-40% range. If the manufacturer does not publish this number, you should ask why and assume its absorption may be too high for expected performance. Due to the way spectrally-selective films are made, they are the most expensive.

Ceramic films are King Almighty in the automotive world, but I do not recommend them for flat-glass applications. Their solar absorption is simply too high for dual-paned annealed glass and don't provide much more performance than a neutral film of the same visible light transmission. If anybody is trying to sell you ceramic for your home or commercial windows, ask to compare the solar performance to a neutral film of the same darkness. Yes, ceramic films are non-reflective, but they're not worth the higher cost. 

Low-E (low emissivity) films provide not only high solar heat rejection, but also winter energy savings. They do this by reflecting the infrared energy (or heat) back into the room (see below for emissivity explanation). Most low-e film products are fairly reflective because of how they're made and are a bit higher in cost. The additional cost is usually well worth it if your windows don't have a low-e coating. If your windows already have a low-e coating, then using a low-e film is moot and will not give you anything additional during the winter season. 

These films are used in areas where added safety from breaking glass is needed or to drastically slow down an intruder when a glass pane is smashed. There are many thicknesses and they come in either clear or solar tinted. Safety films are those with thicknesses up to 7 mils, and are used for basic safety such as when a golf ball hits a window to prevent glass shards from harming people and making a mess. Films from 8 mils and thicker are considered security films. These are used mainly on entry doors or large window panes to slow an intruder. Security films need to be attached to the frame in some manner so the glass can't just be pushed inward. The most popular attachment method is a bead of Dow Corning 995 structural adhesive. There are claims out there that security film makes glass bulletproof. This is not accurate!

Frost films are extremely popular in bathrooms and on doors. They come in a variety of colors, but white is hands-down the most popular. When privacy at nighttime is needed and the view outward is nothing to care about, a frost film is perfect. There are LOTS of decorative films out there if you're looking for some added pizzazz. Click below to check out all of the possibilities. If you see something you like, let's discuss the details, get it ordered and installed.