Upon first impression, steam irons may look like a fairly homogenous field of products that all produce similar results. While this may be true to some degree, we designed our testing methodology to focus on specific aspects of iron performance that had a chance of differentiating between models — all so we could make sure you can milk every ounce of performance possible out of your dollar. We split our tests into four metrics: ironing performance, steam output, heating performance, and ease of use.
We evaluated two aspects of ironing performance: how well wrinkles were flattened out and how easily the iron could glide over fabric (as this is the one characteristic of an iron that you will notice the most while actually ironing). To grade wrinkle reduction, we would lay out a garment, take two different irons, and iron two swatches side by side. This allowed us to directly compare the wrinkle reduction performance of each iron on the same garment. We repeated this process ad nauseam, constantly changing the irons and types of garments. During this test we ironed in a natural manner, moving at a reasonable speed and using the "burst of steam" buttons when it felt like a little extra power was needed. This left us with a pile of data that allowed us to relatively rank the irons in terms of wrinkle-fighting power. The garments were either left crumpled in a hamper overnight to induce wrinkles or, to test really stubborn wrinkles, we would actually iron creases into clothing and then try to iron them back out.
Glide was ranked more subjectively. All of our testers used each one of the irons many, many times, so they were able to get a good feel of how smoothly and easily each one moved over various fabrics and assign accurate scores.
To measure steam output, we filled each iron's water tank to the brim and weighed them. We then dialed in the highest temperature and steam settings, which was generally the cotton setting, and let them preheat for a full three minutes to make sure they got up to temperature. From there, we ironed with each for exactly two minutes, shut them off, and weighed them again. The reduction in weight told us how many grams of water were converted into steam and pushed into the garment in those two minutes, and dividing by two gave us grams per minute. We did not use any steam burst functions during this test.
Ease of Use
All of our testers spent a lot of time with each iron, changing the settings, waiting for them to heat up, refilling the water tanks, and, of course, ironing. So when evaluating ease of use, our testers were essentially able to just score how frustrating or pleasant they found it was to use each model. They considered things like ease of filling the water tank, whether or not there was an indicator to signal when the iron was up to temperature, the general ergonomic feel, and whether or not the cord tended to get in the way. As you can see, we've spent a lot of time thinking about irons, so you can trust our opinion on which one is the easiest to use.
To test heating, we put each iron on its highest temperature setting and let it preheat for five minutes. We then measured the temperature of each in various places on the soleplate, using a very accurate thermocouple — one that was certified by the National Institute of Standards and technology. We chose this methodology because the thermocouple is very precise, and this paints a very clear picture of which models get the hottest and if they heat uniformly (or not) across the entire soleplate.