Lined draperies were the first form of insulation. During the Middle Ages windows, more often than not, were nothing more than openings or slits in the wall. Enterprising homemakers took to covering those holes with oiled linen and cloths. These early draperies not only provided insulation but security, and they were an aesthetic improvement. People no longer could look in from the outside, and the ragged hole in the wall was covered by an attractive piece of cloth.
As windows and window coverings have evolved our primary concerns have not. We still value insulation, security and the look of our windows. Now, though, the best way to improve in all of these areas is to use lining. The additional layer that lining provides offers a substantial improvement in the window's insulation factor for both temperature and noise. Additional finishes and layers can improve that factor further. The heavier weight of a lined fabric hangs better, providing a fuller, unwrinkled effect. It also offers greater shape retention to the face fabric. And, perhaps most important, linings can protect the face fabric from moisture and sun damage, considerably extending its life span.
But with so many different types of lining available, how do you go about choosing the right one for your window treatment? The first step is knowing what's out there. Hal Spalter of Rockland Industries certainly knows what's available, and he offers a breakdown of the linings his company sells. "There are two broad categories: residential and commercial," Spalter begins. "Residential typically are uncoated goods with properties such as water repellency, insulation values, stain resistance and ultraviolet inhibitors." The fiber content of these linings can range from 100 percent cotton to poly/cotton blends and 100 percent polyester.
Also manufactured are rayon and acetate linings that have been treated for flame resistance. Many of these linings come with a layer of foam acrylic for additional insulation. "When you get into commercial lining the first thing you look for is flame retardancy," Spalter says. In order to meet fire codes, the lining should be certified to pass NFPA 701 standards.
In addition to these general categories there also are some specialty linings. The first is blackout lining. Blackout lining is beneficial when it comes to a very important aspect of commercial window coverings: light control. Blackout drapery linings essentially cut off all outside light. Spalter describes their construction. "You start with a base cloth, usually a poly/cotton blend. Then give it either a two- or three-pass of aerocellular acrylic foam, one of which is an opaque layer. A three-pass liner will appear white on the cloth side, so it can be made up as a stand-alone drapery liner. The two-pass blackout eliminates the first coating so that the opaque layer goes directly onto the face cloth. That gives the fabric a gray look to that side." What enables blackout lining to control light so thoroughly is the opaque layer. Both two- and three-pass blackout linings have the same opacity. That is, they block out light equally well.
Due to the high number of layers and the use of an acrylic foam coating, blackout linings offer improved insulation and noise control. This lining keeps nearly everything outside on the outside, and everything inside on the inside. It is like erecting a movable wall in front of your window.
Another form of specialty lining is interlining, which is placed either between the face cloth and the exterior lining or between two thicknesses of the face fabric. Interlining almost always is cotton -- usually it is flannel, but at times it's canvas. It can be as formidable at excluding sound, heat and cold as blackout lining is at excluding light.
The final specialty lining is thermal lining. This lining is designed with climate control in mind. With a layer of acrylic foam it keeps rooms warm in the winter and cool in the summer. It can be used to make heating and air conditioning more efficient. Some companies offer thermal linings that also are ultraviolet resistant and provide a degree of opacity to block bright light from entering the room.
One of the primary reasons to line draperies is to increase the window covering's insulation factor. As mentioned before, a drapery by itself will provide more insulation than the window alone by forming an air pocket between the window and the drapery. Lining that fabric will add another layer and further enhance its insulation effect.
So it follows that the more layers you add to the equation the greater the insulation. But this isn't very scientific. How can we accurately measure the insulation ability of lined window coverings?
Builders rate the insulation of materials using an R-value. Simply put, the R-value corresponds to an object's resistance to heat loss. The greater the R-value, the higher the resistance to heat loss and the better the insulation. A wall, with insulated and non-insulated sections, might have an aggregate R-value of 8.65. According to Spalter, an unshaded window with 1/8-inch thick clear plate glass will have an R-value of 1.2. An unlined antique satin drapery across that window brings the rating up to 1.35. But Rockland's blackout lining alone has an R-value of 1.47. Adding that lining to the draperies would more than double the window's R-value. "The addition of either foam-backed or blackout product does significantly raise the R-value of a window," Spalter says.
Window quilts probably are the most insulative window treatments available. They prevent air movement near the glass by eliminating gaps. Usually, window quilts open and close along tracks mounted inside the window frame or have magnets sewn into the fabric that attach to metal strips on the sides of the window.
Closing off a window with such a quilt could raise its R-value from 1.2 to around 4. This would increase the insulation quality of the entire wall, and thereby improve the cost effectiveness of heating and cooling the entire house.
Measuring the insulation quality of window treatments with R-value, however, will not produce the most realistic value. After adding blackout lining to draperies placed over a window the R-value noticeably increases. But this value is accurate only when all of the window coverings are tightly closed.
Betty Lasseter, a residential designer in Asheville, NC, compares using R-values on window treatments to figuring miles per gallon for a farm tractor. "The farmer may drive it once a month, or he may drive it every day. But he's not out on the highway; he's out there plowing his fields. He's going to drive the tractor until it's empty then fill it up again. You could figure out a miles per gallon number, but it just wouldn't make sense given the context," she says. In other words, you can figure out the R-value of lined window treatments, but it won't make complete sense unless you keep the draperies closed all the time. Using the R-value to measure window treatments designed to remain open would make even less sense. The value would not be much different from the R-value of the glass itself. As a rule, the greater amount of window you cover consistently and tightly, the higher the insulation quality.
Linings with a layer of foam acrylic compound will retard heat loss most efficiently. The air-filled cells of the foam will restrict the flow of air through the fabric. And if insulation is what you are after, be sure to hang your panels tightly using tracks or magnets. The tighter the draperies around the window, the better the acrylic cells function.
So you must have an idea of how insulative you want the window treatments to be. Once you have that in mind, how do you know which lining is best for your treatments? The first consideration should be the construction of the face fabric. Spalter recommends "a lining with a similar construction as the face cloth, simply because they will hang together better. You will have fewer problems with residual shrinking. And you want both the lining and the face fabric to have the same cleaning requirements." If the outer fabric requires dry cleaning and the lining shrinks as a result, the outer fabric will pucker. If the opposite happens and the outer fabric shrinks, the lining will pucker. So keep the lining and the face fabric compatible.
The second consideration should be any special needs the situation presents:
Will the treatment be installed on a window that receives a great deal of sun? Or, are you installing a sun-susceptible face fabric? If so, you'll want a lining with a special treatment for ultraviolet protection. In addition, you'll probably want lining with some degree of opacity to cut down on glare. It also is a good idea to buy extra when purchasing the face fabric for such a window treatment. The turned-back edge of the face fabric might rot before the lined portions of the draperies. With the extra fabric you can easily replace that edge to extend the life of the treatments. Are the draperies going in the kitchen or some other stain and water susceptible location? If so you'll want a stain-resistant finish to your lining. Such finishes will protect against mildew, discoloration and the setting of oil-borne stains. Stain-resistant finishes lower the fabric's ability to absorb moisture, therefore preventing the growth of mold and mildew and allowing you to clean the fabric easily. If you are hanging a fabric prone to wrinkling, it also would be a good idea to use a lining with a high thread count. Such a lining will provide a full look and feel to the fabric and prevent wrinkling down the line. If you intend to hang treatments such as Roman shades, swags or cascades, interlining would be recommended. Interlining will render a full shape to your treatments, supply a greater amount of insulation and preserve your customized treatments even longer than normal lining. Interlining also would control external sounds such as trains, planes and traffic, or keep sounds inside your home if that is a concern.
Whatever your situation and need, don't be left out in the cold, even when it comes time to choose a lining. It is an important consideration that can greatly affect the quality of your window teatments. Taking time now to figure out which lining is best for you and your window treatments can save you the hassle of having to replace deteriorated or inadequate window treatments later.
Cheryl Strickland is owner of Professional Drapery Seminars. She is an internationally-acclaimed speaker with more than 20 years experience in the window coverings industry. She is the publisher and editor of Sew WHAT?, an international monthly newsletter for professional drapery workrooms. Strickland also is the author of A Practical Guide to Soft Window Coverings and the Designer's Sketch Pad, which are available through Draperies & Window Coverings magazine.