Inside Consumer Reports Test Labs: Putting carpet shampooers through their paces

Last week we told you about a scary-looking tool our technicians are experimenting with to embed pet hair into carpeting as part of vacuum testing. This week, for our scheduled March 2010 report on carpet cleaners (online and on newsstands in early February), other testers have been using a big roller that grinds topsoil into panels of off-white carpeting. This device is designed to replicate the abuse the carpeting in your home might be subjected to by a gaggle of dirty-sneaker-wearing kids.

The testers let the dirt set for 24 hours then vacuum the panels with a conventional upright vacuum. Next, they use a carpet cleaner (shown) filled with the manufacturer-recommended solution. To determine how well each appliance cleans the carpeting, testers use a colorimeter to measure the color change from the cleaning process.

Known by a variety of names—carpet shampooers, extractors, carpet cleaners, deep cleaners—the 11 different machines we're testing include a rental model and two handhelds. Among the messes these cleaners have to tackle in the lab are coffee, red wine, and tomato sauce. And since wet carpeting can develop mold or mildew, testers also weigh the panels before and after each test to find out how much moisture remains. Beyond that type of quantitative analysis, testers also look at how convenient each machine is to use and which features matter most.

We're aware that many of you are deeply interested in carpet cleaners, so we'll continue to update you on our testing. —Kimberly Janeway | e-mail | Twitter | Forums | Facebook

Essential information: Our free buyer's guide to carpet cleaners offers helpful shopping advice. If you're looking for a new vacuum, check out our ratings of canister, upright, and stick and handheld models (available to subscribers).