How We Test Laundry
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Reviewed.com Laundry tests washing machines and clothes dryers using a rigorous set of scientific methods, using the same tools and techniques that the manufacturers themselves use to test their own products. This allows us to determine the performance of a washer or dryer in detail and to discuss the pros and cons of a product with solid scientific data.
While other sites do a couple of measurements and assume that this tells them all they need to know, we take thousands of measurements over a long period of time and analyze these results using a number of sophisticated mathematical techniques. Our testing is based on industry standards created by industry bodies such as the American Society for Testing and Manufacture (ASTM) and the International Electrotechnical Commission (IEC), all of which allows us to really understand how washers and dryers perform.
Instrumentation & Data Analysis
To test the performance of washing machines, we use a number of industry standard tools to measure temperature, power use and other performance factors.
To measure the temperature of the wash and the air used to dry clothes, we use iButton sensors, which are placed inside the wash in waterproof containers. These small sensors measure and log the temperature every minute for an entire wash or dry cycle, allowing us to measure the temperature inside the appliance without opening the door or having cables running through the door. These sensors measure the temperature with an accuracy of .0625°C within a temperature range of 0°C to 85°C, with each sensor having the capacity to hold over 8000 measurements. The data these buttons capture is saved to a computer and analyzed in a custom-built Excel spreadsheet.
To measure the water use of washers, we use a pair of water meters designed for hot and cold water. These are accurate down to 0.01 gallons.
The electricity use of washers is measured by a Watts Up .Net power meter. The energy use of dryers is measured by a TED 5000 energy monitoring system that is tied into the power supply distribution panel to measure the power use of each dryer individually. Both systems log the data to a web site for later analysis.
The color of our wash test strips is measured with an X-Rite Eye-One spectrophotometer.
Our tests are carried out in a custom-built, climate controlled test facility, which is temperature and humidity regulated. This ensures that tests carried out at different times take place under the same test conditions, with minimal variations in temperature and humidity. The washers are run on individually fused electricity circuits, and are supplied water by a standard domestic sized water line. The hot water is heated to 120 degrees by a high capacity water heater.
Stain Strips – To test the washing performance of washing machines, we use cotton test strips that include 5 different stains: simulated sebum (human sweat), carbon black (a mix of carbon and oil), pig blood, cocoa and red wine. All of these stains have been evenly applied and allowed to fully dry.
Wear & Tear Sheets – To test the amount of wear that washers apply to clothes, we use mechanical action test sheets made of cotton, with a number of carefully cut holes that expose the cotton threads. We measure the number of threads that become dislodged during a wash cycle. Each sheet is used for one single test, and they are not reused.
Detergent – To ensure a level playing field between washers and across wash temperatures, we use a standard detergent, which is based on the AHAM HLW-2010 Formula III. This avoids any possible bias from detergents that favor or work better with a certain temperature or type of washer.
Dirt – For our dirt removal test, we use Ottawa-type sand that has been graded to be passed by a #30 screen, but captured by a #20 screen. The sand is captured exiting the wash by a filter on the output pipe, and the lint is filtered out after the wash is complete.
Wash Loads – We use a number of different test loads in our testing, depending on the temperature of the wash. Our cotton load is composed of cotton towels, shirts, sheets and pillowcases. Our mixed load is composed of cotton towels and cotton/polyester shirts, sheets and pillowcases. We log the number of times they have been used, and regularly replace them to avoid any issues with them becoming overly worn.
For most washing cycles, we use an 8 lb (dry weight) load. For quick wash cycles designed to wash a smaller number of clothes more quickly, we use a 4 lb (dry weight) load.
Washing Performance Test
To test the washing performance of a washer, we use the stain strips described above. Three of these stain strips are attached to towels that are placed in the washer with our test load.The items in the test load and the strips are put into the washer in a standard order.
After the wash cycle is complete, the strips are allowed to dry flat away from all light sources. Once they are completely dry, we measure the color of the strip in the XYZ color space. Each stain is measured in 4 locations, and the results are averaged.
Our scoring for this test is based on the amount of difference in the Y color co-ordinate between the pre- and post-wash strip. The bigger this difference, the more of the stain has been removed, and the better the washer. Our scoring is standardized to measure the performance relative to a high-end washing machine that is used widely within washing machine test labs. Our overall score is based on the average performance for each of the 5 stains from multiple tests across 5 standard wash cycles: Normal, Cotton/Whites, Delicate, Heavy Duty and Quick.
Wear & Tear Test
To test the wear and tear that washing involves, we used multiple standard mechanical action test sheets that are inserted into the wash. After the wash cycle is complete, these are carefully removed and allowed to dry flat. We then closely examine the sheets to see how many of the cotton threads have become loose. All of the holes in the sheets are examined (there are 5 holes per sheet), and multiple sheets per wash cycle are used.
The scoring for this test is based upon the number of threads that have been loosened. The more loose threads, the more wear and tear there is on the clothes and the lower the score. The results for all 5 of our standard test cycles are averaged to produce the overall score.
To measure how much water remains in the test load after it is washed, we measure the bone dry weight of the load before washing, then measure it again immediately after the wash has been completed.
The score is based on the percentage of the post-wash weight that is water: the higher the percentage, the lower the score. Again, the overall score is averaged across the 5 standard cycles.
To measure the effectiveness of the washers at removing insoluble dirt from the load, we add a known quantity of sand to the load before washing. We then measure how much of this sand ends up in a filter placed at the washer outlet, and how much remains in the load. To ensure that water or other material adhering to the sand does not affect the result, we dry the sand before it is weighed and put into the load. Then we filter, wash and dry the sand again after it is captured.
The score for this test is based on the percentage of the sand that the washing machine removes from the load: the larger the percentage, the larger the score. We run this test in 3 cycles (quick, normal and heavy duty).
We test the performance of dryers by wetting a standard clothes load or a test comforter so that the weight increases by 60 per cent to simulate the dampness of clothes that have just been extracted from the dryer. We then place this in the dryer, along with two iButton temperature and humidity sensors and set the dryer going. After the dryer stops, we remove the load and weigh it again to see how much water is remaining. We also retrieve the data from the iButton to see what the temperature was inside the dryer while the cycle was running.
All of our tests are timed using stopwatches to ascertain how long they take to complete. We do not use the estimated time indicators on the dryers, as they are often extremely inaccurate
Per Wash & Yearly Running Costs
Our figures for the cost of a wash and the running cost of washers are based on the combination of the following individual costs:
- Electricity to run the washer
- The cost of water
- The cost of the gas used to heat the hot water
We do not include the cost of the detergent, as the cost and quantity of detergent used can vary widely.
We calculate these using the following assumptions:
- An electricity cost of $0.013 per Kilowatt Hour
- A water cost of $5.41 per 1000 gallons
- A gas cost of $1.31 per therm.
The yearly cost is based on an average of 392 wash loads per year, with 50% of these loads done in the normal cycle, 15% each in the cotton/white and heavy duty cycle and 10% each in the delicate and quick wash cycles.
We believe that this approach provides a good representation of the typical use that a washer and dryer will get with an average family. However, the cost to run a washer and dryer can differ from user to user based on a large number of factors (electricity cost, water cost, gas cost, etc), so this number should be used as an estimate for comparative purposes, not as a guide to the actual cost.
EnergyGuide – Our approach differs from the one used for the EnergyGuide labels seen on washers. These labels include figures for energy use and running cost, but are based on the cost of one single cycle. So, our numbers will differ from the EnergyGuide numbers.