Lint, that fluffy mix of textures and colors, is not mentioned on care labels of clothing and other textiles, yet it's the inevitable byproduct of just about everything that comes out of a clothes dryer.
Lint is so common -- and potentially dangerous -- that every dryer has a filter to catch it. Typically, it's a somewhat awkward pullout screen that gathers fuzz even from items that have been washed many times.
Manufacturers and the Consumer Product Safety Commission (CPSC) recommend cleaning lint traps before or after each load. But even with diligent maintenance, some lint slips through.
Typically, it lodges in the exhaust line just inside the exterior outlet or at an elbow fitting along the way. Worse yet, it may lodge in or near the dryer itself, where a backup of this nearly perfect fire tinder could ignite.
The safety commission estimates that each year there are almost 15,000 clothes-dryer fires resulting in 300 injuries and about $90 million in property damage. But the Washington-based Association of Home Appliance Manufacturers (AHAM) says that many incidents reported as appliance-related do not actually occur in appliances. The association says "the alleged clothes dryer safety-related incident numbers issued by CPSC are significantly overstated."
Whatever the precise statistical risk, lint accumulations typically cause three types of problems:
Small blockages reduce the dryer's efficiency by limiting airflow, which makes the appliance take longer and use more fuel to dry clothes. As lint blockages further reduce the exhaust path, dryers may overheat, shortening their lifespan and risking wiring and motor damage. Large accumulations can eventually block the escape of lethal exhaust gases (from gas dryers) and also start fires.
Safety commission data records 11,500 fires with electric machines and 3,100 with gas models. But one type is not inherently safer than the other. The number of incidents reflects the annual ratio of electric versus gas machines sold.
With either type, problems typically stem from improper installation and maintenance. The AHAM and the CPSC stress cleaning to help prevent fires and not one fuel source over another.
Exhaust system risks
Venting a dryer can be difficult, particularly in basements where the exhaust line has to twist and turn before reaching an exit point above a masonry foundation.
Ducting also forces the dryer away from the wall. Some installation schematics allow nearly a foot of space for ductwork behind the dryer. But few homeowners are willing to give up that much floor space -- or deal with such a huge black hole for stray socks.
One result is that many dryers are connected to flexible ducts and jammed into place. That can crimp the exhaust line and greatly reduce airflow even without any lint in the system. AHAM says that none of its member manufacturers recommend these flexible hookups, typically made of accordion-folding metal foil or the kind of coiled-wire plastic tubing used to vent bathroom fans.
The safety commission says consumers should "replace plastic or foil, accordion-type ducting material with rigid or corrugated semi-rigid metal duct." Flexible plastic or foil ducts can more easily trap lint and are more susceptible to kinks or crushing.
For gas dryers, the National Fuel Gas Code requires rigid sheet metal or corrugated semi-rigid sheet metal ducting. Professional installers can use an angled fitting at the back of a machine to minimize wall clearance.
For electric dryers, the International Residential Code allows flexible, or transition, ducts that conform to Underwriter's Laboratories standards (UL 2158A) in single lengths not exceeding eight feet and not concealed inside construction. AHAM and the CPSC recommend gas-type metal ductwork even for electric dryers.
If you choose to use flexible duct, check with your local building department about code compliance.
Do's and don'ts
Aside from cleaning the lint trap, clothes dryers seem to be maintenance-free. But there are a few things to do -- and not to do -- including the obvious advice of following manufacturers' instructions.
The main deterrent against problems is cleaning, including a check outside while the dryer is operating to make sure exhaust air is escaping. Also clean behind the dryer where lint can build up. If you notice that drying time is longer despite cleaning, consider a service call to have the entire vent system (inside the machine, too) checked and cleaned.
To clear lint from a long vent yourself, consider a tool such as the LintEater system (www.linteater.com), made by the Connecticut-based Product-Worx Inc. The flexible rods and brush attachments (about $40) connect to any cordless drill and twist lint out of exhaust lines.
As to installations, use metal tape and not sheet metal screws to secure sections of metal ducts. The protruding points of screws make perfect lint traps.
Safety groups warn against other fire hazards as well, for instance, drying clothes soiled with volatile chemicals such as gasoline, and suggest washing them twice before drying.