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Thread: Sunlight and UV ray damage

  1. #1
    Join Date
    Jul 2008
    Alexandria VA

    Default Sunlight and UV ray damage

    This article in the Washington Post today, definitely worth reading. Sunlight fade is one of the major issues with taking the color out of leather, and causing fabric to deteriorate. I have had this solar film installed in my home 17 years ago and it works.

    By Jeanne Huber
    May 29

    Q: My apartment — on the 12th floor, with southeast exposure — is wonderfully sunny. Plants do well, and I enjoy the light and the view all day. However, the sun has bleached both wood and upholstered furniture and some carpet. I don't want to close the drapes and live in the dark. Can my windows be treated? Who does this work and what is the expected cost?

    A: Having window film installed on the inside of your windows could be the solution. These films come with a wide variety of characteristics, enabling them to let certain wavelengths of light through while reflecting or absorbing other wavelengths.

    Window film cannot totally prevent fading because other factors, such as humidity, account for about 5 percent of the problem. But depending on the window film you select, it can go a long way toward reducing the problem. All films block virtually all ultraviolet rays from the sun, which are responsible for about 45 percent of fading. Films also can block the rays that together cause about half of fading: visible light and infrared light, which causes heat.

    Because you live in a tall building with many other units, begin by checking with the building managers about whether there are restrictions on window films. Some types make windows a lot more reflective on the outside. Some buildings have no rules on this, and let occupants decide how to treat their windows. Others want a uniform exterior appearance and rule out highly reflective films.

    Once you know the rules, make an appointment to have a window film installer visit your apartment. Installers typically bring samples so you can see the differences in how the films affect your light and your view. Installers can also recommend suitable options if you have double-pane windows, because films that absorb infrared light can cause glass to heat up enough to break the seals or glass and void warranties. Be sure to ask the installer to leave you with a sample or two of films you like so you can check the effect in different conditions: sunny and cloudy and on different times of the day.

    Before the visit, read up on the basics about window films. It will help you ask better questions and help keep you from wondering later whether you got an honest sales pitch. One good place to start is the Efficient Window Coverings website,, which allows you to compare the benefits of various window treatments — from films to drapes to awnings — and then drill down to the highest-rated products in each category. This website is focused on energy savings, which you didn’t mention as a prime consideration. But solving your fading issue can also save energy, so failing to factor that in would be shortsighted. And one benefit of using this website as a starting point is it doesn’t have a financial stake in its recommendations. It was developed by the Lawrence Berkeley National Laboratory in partnership with Building Green (, a consulting and training company that began as the publisher of Environmental Building News, a newsletter that played a pivotal role in developing the green building movement.

    This website uses the term “applied film” to distinguish the type of film you might want from “seasonal film,” which is the shrink-wrap-type plastic that people sometimes put up in the winter to cover drafty windows. Of all the many interior window treatments, applied film ranks highest if you select “view” and “visible transmittance” (i.e., the amount of visible light) as crucial factors and “solar heat control” and “glare control” as important ones.

    For window-film manufacturers, the site lists only companies that meet two criteria. Their products must be tested according to standards from the National Fenestration Rating Council, the same industry group that ensures uniform comparisons of the energy issues related to windows. And the manufacturers must warranty their products for at least 10 years. The site says only three companies meet these standards — Johnson Window Films (, Solar Gard ( and Solutia Performance Films, which recently became part of Eastman Chemical Co. ( The manufacturers can point you to installers in your area.

    Estimating the installed cost of window film is difficult without knowing all the specifics — the size of your windows, how high they reach up from the floor, and whether the glass consists of large panes or small panels. And, of course, the cost varies by the type of film you select. The sales manager at General Solar Co. in Gaithersburg (301-231-9500;, which carries Eastman’s Llumar line of window films and others, said that for 100 square feet of windows, the cost of film and labor could run $9 to $24 a square foot. The Efficient Window Coverings website estimates costs based on a single window 30 inches wide by 60 inches tall at $80 for standard films and $125 for ones that let more visible light through while rejecting other wavelengths, such as infrared.

    If you can afford it, professionally applied window film is definitely the way to go. The product selection and warranties are better, and there’s less risk of having hair, lint or other debris trapped between the film and the glass. But for people on a tight budget, especially for renters who aren’t sure how long they will stay, *do-it-yourself installation is an option. Efficient Window Coverings estimates the DIY-installed cost for that *
    30-by-60-inch window at $10. DIY films include ones that are glued on via an adhesive backing and ones that grip the glass through static cling. Gila Platinum Heat-Control Window Film blocks UV, lets most visible light through, and cuts down on heat. It’s $37.97 for a 36-inch by 180-inch roll at Lowe’s). Gila is an Eastman brand, one of the companies recommended by Efficient Window Coverings, but in this DIY product it comes with a two-year warranty, including against breaking seals or glass in double-pane windows, provided the windows are still covered by the manufacturer’s warranty.
    © 1996-2018 The Washington Post
    Duane Collie
    Straight answers from thirty-six years in the business.
    My Private Messages are Disabled - Please ask questions here in the forum.

  2. #2
    karlos Guest

    Default Re: Sunlight and UV ray damage

    Hi Duane, on my 9 yr old Kodiak sofa I have worn out the seat cushions finish ,Antelope harness. My better half says can i fix it....question ? can I upgrade the leather inserts to capri? a contrasting color might work, Butternut looks close??? what have your customers done with the wear issue. THX again. ITS summer in wa finally. time for waxing the Bmw and taking roads trips!!!, thx Karl

    Hi Karl,

    That's too expensive a sofa to replace, so yes - fix it. Antelope is a high-end finished (painted) German leather and part of what has made it so supple and desirable is the finish is put on very lightly on that hide so it doesn't feel "plasticy". If that were my sofa, I'd remove the cores and UPS the casings to Pamela at Leather Solutions International in North Carolina. Pamela is so good at doing restorations, she actually trains all the major factories in North Carolina (including Hancock and Moore's people) on how to do it. They'll be gone about two weeks, but come back to you ready to go again for a whole lot less than new casings.

    If you want to replace the casings both Antelope and Capri are GR 4 hides, and the new seat casings are $ 340 apiece (x 3 = $ 1,020) plus shipping. I would go the restoration with Pam first, likely will be about 1/3 of that.

    Wish it were summer in Washington DC, I feel we live in tropical monsoon region. On our 20th day of flooding rain (had two days of sun only the past three weeks).
    Last edited by drcollie; 06-03-2018 at 06:22 PM.

  3. #3
    Join Date
    Feb 2018

    Default Re: Sunlight and UV ray damage

    Thank You Duane for this useful info. I too was recently researching about window films for my house after recently placing my order for H&M sofas with Duane. I was planning to share what I learnt about window films when Duane posted this timely article. There are a lot of films out there and trying to identify how to compare them was pretty daunting initially. There are films for different needs and while some may be better than others I felt it was important to understand what your needs are and how to go about looking for them.

    Films for Sun Control fall into these categories:

    1) Reflectives like Copper and shiny aluminum
    2) Reflective Neutrals which are grey to grey black because of the dull looking metals used like stainless steel, nichrome and titanium
    3) Dual Reflectives, which are are less reflective on the inside, than the outside for better Night Vision, basically the outside has a reflective metal and the inside does not
    4) Non Reflectives which usually have a significant amount of color/dye added and no metal or ceramic added (these films will fade or change color in 1 to 5 years)
    5) Spectral Select films are made to allow in more light than these other films, but still stop a great deal of heat. These films usually stop a larger portion of heat light or infra red light to allow in the visible light.

    For home use 3) and 5) are ideal. You will however pay more for the Spectral Select films compared to Dual Reflectives - about double the cost.
    First some very useful information about windows and how they work - this was one of the best articles I found online

    Since most people on this forum are looking to protect their leather furniture and wood floors be sure to follow into following links

    I would encourage all to dig into the links in the above page
    Glare tutorial -
    UV transmittance and Fading -
    Solar Gain -

    Don't get scared away by the graphs and the formulas - it isn't all that bad. Even if you grasp half of what the articles talk about you will come out way more informed than the average consumer.
    The paper below - I think tries to summarize lot of the information above in a single article (pdf) rather than multiple webpages

    Now that you are armed with basic information about windows and films you are ready to go shopping. I had a few vendors bring me window film samples from different companies/brands. Believe me there are way too many brands and each carry different lines. The sample films are smaller than 8.5"x11" and they will place them on the windows and leave them with you for you to compare. Some of you may have a good eye, but for me this did not help one bit in shortlisting the film that would be ideal for me. They all looked same except for a few extremes
    What might have helped is - maybe go to a showroom with different films installed on real windows for you to compare - good luck trying to find such a place.

    So I had to fall back on the spec sheets for the different films to identify what parameters were really important to me. This is where all the links above were really useful.

    Here's a review of some of the key terms -

    So what are the specs that really matter in choosing the solar film that is right for you ?

    % Visible Light Transmittance (VLT): Think of it as the amount of light that is allowed to be transmitted through the window/film. Light is (UV+Visible+IR). It is specified as a %. A VLT of 10% will block 85% of the visible light and a VLT of 35% will block 65% of the visible light. From what I have read, starting from VLT of 20% going down, your eyes will start noticing the room getting darker. A VLT of 20%-40% will allow enough light in without making the room seem darker. Out eyes are supposed to be very good in adapting to the variation of VLT without affecting the visibility.

    Solar Heat Gain Coeff(SHGC)/Total Solar Energy Rejected(TSER): The SHGC and TSER are the inverse of each other. SHGC is a value between 0-1 and TSER is a % between 0-100. Thus, if the TSER of a specified film/glass combination is 58%, then 1 - .58 = .42, which is the SHGC of the window.
    So what is a good value of SHGC - one of the articles I read recommended staying below a SHGC of 0.4 i.e. choose a TSER of 60% or more.

    LSG: The articles above will talk about another ratio called LSG (Light to Solar Gain Ratio) which is nothing but VLT/TSER. They recommend that one look for a value of 1 or higher - this way there will be more light transmitted than heat.
    Please note that LSG ratio of 1 or higher is for the windows - when it comes to solar film you will rarely see this ratio go above 1. What this ratio does not take into account is the exterior and interior reflectance of your solar film.

    Visilble Light Reflectance (VLR) Int/Ext :Your solar film will typically specify both exterior and interior reflectance of the visible light and will be a % between 0-100. The values here will determine how shiny or mirror like the film will be when applied to your windows. Typical residential/architectural films have different internal/external reflectance with the interior reflectance being lower than exterior reflectance. Most popular line among all manufacturers are called - Dual reflective films which have lower internal reflectance than exterior reflectance which allow better visibility from inside the house without being too reflective. Reflective has its benefit as that helps reject heat/light but we have to determine the right balance that suits our needs.
    As reflectance approaches around 30% the film will appear darker/blacker and as that value goes higher 40% or more the film will appear more silver. Clear glass has a VLR of about 8%.

    So what are good VLR numbers to look for. From what I have learnt and seen so far it seems that one should look for a Internal VLR of 20% or lower - this would afford you good visibility from inside the house without feeling too mirror like. For external VLR - I was looking for a value below 40%. Higher values of External VLR will typically give you better values of TSER - so you have to play with these two parameters to determine your sweetspot.

    Total Solar Energy Absorbed: For dual pane glasses - choose a film with Total Solar Energy Absorbed less than 50%. This will reduce the chance that the film absorbs too much heat and breaks the seal of your window panes. In case this happens - most films warranty your window and film replacement.

    Emissivity : One typically shoots for a lower number here - typically for the films I saw the values ranged between 0.6-0.8. The emissivity for cold climates ( you are trying to keep heat inside the house) is different than that of hot climates (you are trying to reject heat coming into the house). Films/windows for cold climates would typically be different in this aspect.

    Here is a good blog from a vendor who tries to educate their customers

    In the article from WashingtonPost that Duane posted above, refers to
    which states - The site says only three companies meet these standards — Johnson Window Films (, Solar Gard ( and Solutia Performance Films, which recently became part of Eastman Chemical Co.
    This information is probably dated and incorrect. The site lists - lists the companies that meet the standards.
    Click image for larger version. 

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    What about payoff for installing Solar films ?
    If you have non-tinted clear glass, your payoff would be fastest as expected. The above paper lists potential payofff based on your climate zone also compares costs and rate of returns as opposed to replacing the windows itself.

    How about the cost of installing these solar films ? I have too many windows to do this myself. I live in in Dallas, TX area and around here the cost to install an Dual Reflective film would range between $4-$5 per square foot. If you choose a spectrally select film expect to pay about twice this amount.

    If you have survived all of this and are curious to see what I shortlisted, see below
    Click image for larger version. 

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    My criterion for shortlisting was a Dual Reflective film to keep costs down, a VLT between 20-30% so that the room does not get too dark, a SHGC of less than 0.4, a VLR interior of less than 20% and a VLR exterior of less than 40. My final 2 were the Suntek Symphony DS Dual Reflective SYDS-25 and the Madico Sunscape Starlite 28 and I ended up selecting Suntek Symphony DS Dual Reflective SYDS-25.

    I will be the first to admit - that there is probably a lot more to selecting films and I do not claim absolute accuracy on what I have posted, but hopefully you will be more educated in the process to confidently select the film that suits your needs.

    Thank you

  4. #4
    Join Date
    Jul 2008
    Alexandria VA

    Default Re: Sunlight and UV ray damage

    When we first moved into our house 17 years ago, I knew the UV rays were going to be an issue and very quickly hired a company to come in and apply solar film to the (5) upper windows in our main family room, I did not do the sliding glass doors (to save money!). The three main windows face east, the two on the other wall south. We also did all the other windows on the south and west sides of the home. I skipped some of the morning sun east and all of the north windows. We also picked the lightest film, fearful of darkening the room.

    As it turns out, those eastern windows we didn't cover allowed the sun to really nail the wood floors over the years and artwork, as well as everything else in their path. My rationale was morning sun coming in over 50 foot poplars wasn't a big deal - I was wrong in that assumption. Also, anything near the three sliding glass doors also faded badly. Three years ago we replaced the three sliders with Anderson doors and I spec'd the extra cost "Florida" tint which was even more aggressive than the standard UV Glaze they do. That has stopped the fade in the room completely for us, and was a good move to do that.

    The tint does not darken the room, if anything it cuts the glare way down from regular glass. Even though you won't notice the slight darkening, you will notice the absence of glare. A few years ago one of those large windows cracked and had to be replaced, and we could not believe the glare from it until we could get the solar film guy back in to apply it to the window.

    I'm definitely an advocate of finding a way to cut the UV rays down. It will save everything in the room that has any color to it and will make what you have last longer. Its not all that costly (unless you have small individual panes) and a good investment when you have sunlight streaming into the room.

    BTW, that's a 17-year old pure-aniline sofa in the photo - the one I recently re-dyed to restore the color using products from Leather Solutions International. It suffered sun damage from those three non-treated sliding glass doors until I replaced them.

    Click image for larger version. 

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    Last edited by drcollie; 06-03-2018 at 05:46 PM.
    Duane Collie
    Straight answers from thirty-six years in the business.
    My Private Messages are Disabled - Please ask questions here in the forum.

  5. #5
    karlos Guest

    Default Re: Sunlight and UV ray damage

    thx Duane I will send them in for a re- stain. I am still curious how close a match capri butternut is to antelope harness. have you ever had finish scuffing issues with capri? At 10 yrs old my Hancock sofa is still looking perfect except for the seat scuffing. I compare that with other furniture in the house , no comparison , my lazy boy/Chinese crap all went to the dump at 10 yrs. ripping staples poking u etc... We talked about rain now its back for us!!! aggghh

  6. #6
    Join Date
    Jul 2008
    Alexandria VA

    Default Re: Sunlight and UV ray damage

    I'd have to see a photo to look at what is going on with your existing Antelope casings.

    Capri is a pure aniline, so it doesn't scuff - however its a pure naked leather so its more susceptible to staining and will definitely fade if exposed to direct sunlight. Colorwise, Capri Butternut is very close to Antelope Harness.
    Duane Collie
    Straight answers from thirty-six years in the business.
    My Private Messages are Disabled - Please ask questions here in the forum.

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